Phytochemical Fingerprints by GC–MS, Antidiabetic and Multiorgan Protective Effects of Cucumis sativus Peel: An Integrated In Vitro, In Vivo, and In Silico Study

ABSTRACT

The present research study explored antidiabetic, antioxidant, and organ‐protective properties of Cucumis sativus (cucumber) peel powder (CPP) and ethanol extract of cucumber peel extract (CPE) in alloxan‐induced diabetic rats (DR). Chemical profiling of C. sativus peel was done by using GC–MS. The male albino rats (n = 36) were split into six groups, which includes normal control (NC), diabetic control (DC), CPP 5 mg/kg oral gavage (CPP‐5), CPP 10 mg/kg (CPP10), Cucumis ethanolic extract 5 mL/day (CPE5), and Cucumis ethanolic extract 10 mL/day (CE‐10). Treatment was applied over a period of 28 days by oral gavage after the induction of alloxan (150 mg/kg). A histopathological study was performed on the pancreas, kidney, and liver. In silico study was performed to check the binding affinity of the phytoconstituents with α‐amylase. GC–MS identified bioactive fatty acids, including 9‐octadecenoic acid, linoleic acid, and hexadecanoic acid derivatives. Treatment significantly reduced fasting blood glucose and improved insulin levels, lipid profiles, and normalized liver and renal function markers. Histopathological findings showed restoration of pancreatic, hepatic, and renal architecture. Molecular docking revealed strong binding affinity of 9,12,15‐octadecatrienoic acid (−6.00 kcal/mol) toward α‐amylase. Cucumber peel shows promising antihyperglycemic, antihyperlipidemic, and multiorgan protective effects.

Alloxan‐induced diabetic rats demonstrate significant improvement following treatment with Cucumis sativus peel extract. The peel exhibits antidiabetic, hypolipidemic, antioxidant, and multiorgan protective effects, supported by GC–MS profiling, biochemical assays, histopathology, and molecular docking. These findings highlight cucumber peel as a promising bioactive resource for diabetes management and mechanistic exploration.

1. Introduction

Diabetes mellitus is a long‐term metabolic disorder, which is marked by high levels of blood glucose, which is caused by a lack of sufficient insulin secretion, insulin resistance, or both processes [1]. Recent data show that out of 828 million of diabetes patients in the world, 95% are type II DM, and statistical data showed in 2050, cases of Type 2 DM will increase to 10.8% [2]. This disease may cause serious consequences as it can disrupt the metabolism of proteins, lipids, and carbohydrates without receiving treatment [3], which leads to complications of the DM to retinopathy, nephropathy, and poor quality of the life of the patients [4].

Role of oxidative stress in diabetes mellitus onset and progression. Oxidative stress is critical in the pathogenesis and development of diabetes mellitus. Chronic hyperglycemia elevates the production of reactive oxygen species (ROS) because of mitochondrial malfunctioning, the autoxidation of glucose, and advanced glycation, which exceeds the antioxidant capabilities, including superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) [5, 6]. This imbalance facilitates lipid peroxidation in which the reactive radicals destroy polyunsaturated fatty acids to form damaging aldehydes, including malondialdehyde (MDA) and 4‐hydroxy‐2‐nonenal (4‐HNE) [7]. These aldehydes form adducts with proteins and nucleic acids, which interfere with the membrane integrity, the insulin signaling, and the cellular metabolism. As a result, β‐cell dysfunction, insulin resistance, and vascular complications, including nephropathy and retinopathy, are accelerated because of oxidative stress and lipid peroxidation [8, 9]. The existing antidiabetic medications, including metformin, sulfonylureas, thiazolidinediones, and insulin analogs, successfully decrease hyperglycemia but do not always achieve long‐term metabolic stability and are also characterized by significant side effects. Metformin is not the first‐line treatment that may induce gastrointestinal discomfort and lactic acidosis in vulnerable patients [10]. Sulfonylureas cause insulin secretion and can cause hypoglycemia and weight gain [11]. Thiazolidinedione enhances insulin sensitivity by reducing insulin resistance but creates the risk of edema, heart failure, and bone fractures [12]. In addition, long‐term synthetic use can also cause oxidative stress and become ineffective with the course of time. These difficulties explain why more sustainable solutions are necessary. Compounds of natural plants have demonstrated encouraging antidiabetic, antioxidant, and lipid‐lowering properties, with numerous polyphenols, flavonoids, and antioxidants, which means that it is a holistic approach to managing diabetes with fewer adverse reactions [13, 14].

Plant‐based diets contain high fiber and phytochemical levels, and due to these, have demonstrated promising outcomes in managing and preventing diabetes, thus potentially being a safer alternative [15, 16, 17]. Antioxidant and enzyme‐inhibiting properties of natural substances, and phenolics in particular, could be effective to reduce glucose levels in the blood and decrease oxidative stress [18]. The cucumber (Cucumis sativus L.) is a vegetable that can be found globally and belongs to the Cucurbitaceae family since it has a cooling and hydrating effect. Cucumber has great nutraceutical and pharmacological potential besides being used in cooking. The peel, which is typically discarded as agricultural waste, has a high concentration of bioactive compounds, including polyphenols, flavonoids, tannins, and vitamins A, C, and E, which have been known to have strong antioxidant and free radical scavenging effects [19, 20, 21]. They are caffeic acid, p‐coumaric acid, quercetin, and apigenin [22], which help the cucumber peel to have anti‐inflammatory, antidiabetic, and hypolipidemic reaction. Methanolic extract taken out of pumpkin emission and C. sativus has been found protective to the pancreas and liver against diabetes induced damage [23]. Hydroalcoholic and buthanolic extracts of the seeds of C. sativus were found to have a role in diabetic control (DC) in rats [24]. Another member of this family, Curcumis melo L. is reported to have antioxidant and antidiabetic activities [25]. Another study using the response surface methodology (RSM) was performed on the extraction of bioactive compounds and their optimization of antidiabetic activities [26]. A review article on the phytoconstituents and biological activities of C. sativus has been reported, which left the antidiabetic part unaddressed [21]. Fruits of C. sativus have been reported to have antidiabetic activities [27]. The peel is rich in antioxidants and bioactive compounds that are able to alleviate oxidative stress—a primary cause of diabetes pathogenesis [23]. Nevertheless, the special consequence of cucumber peel extract (CPE) on hepatic, renal, and cardiac complications caused by diabetes, being the key factor of diabetic morbidity, has received little study attention [28]. The antioxidant and therapeutic properties of cucumber peels are especially high, and the cucumber seeds are antiulcer [29, 30].

C. sativus (cucumber) has been widely studied for its nutritional and pharmacological benefits, yet most research focuses on fruit and seeds, leaving the peel largely unexplored despite its rich phytochemical profile. This study investigates, for the first time, the antihyperglycemic, antihyperlipidemic, and organ‐protective effects of CPE in alloxan‐induced diabetic rats (DR). In addition, an in silico antidiabetic analysis will identify key phytoconstituents (via GC–MS) and evaluate their interactions with α‐amylase protein, which is one of the major targets in diabetes management. Histopathological evaluation of the pancreas, liver, and kidneys will further clarify the peel's protective potential, offering a promising natural therapeutic candidate for diabetes.

2. Materials and Methods

The study was done in the Department of Human Nutrition, Faculty of Food Science and Nutrition, Bahauddin Zakariya University, Multan, and aimed at assessing the therapeutic value of cucumber peel powder (CPP) and extract on diabetes.

2.1. Plant Collection

Fresh cucumbers (C. sativus) were purchased in Head Muhammad Wala, District Multan, in December 2024, and a reference sample (1165/ SC) was kept in the Herbarium of Faculty of Food Science and Nutrition, Bahauddin Zakariya University, Multan, Pakistan, washed with distilled water before being peeled.

2.1.1. Preparation of Powder and Extract

The peels were rinsed thoroughly with distilled water to get rid of the dirt, dust, and the adhering impurities. Clean peels were then subjected to sun drying for 5–6 days, which was to ensure reduction of the moisture content. The dried peels were finely ground by using an electric grinder (Model BJ‐9176) to get CPP. For preparation of the extract, powdered sample was soaked in 95% ethanol (solid/solvent ratio 1:10 w/v) and maintained on a shaker over a 48‐h period at a moderate temperature. The resultant mixture was filtered by using Whatman No. 1 filter paper, and the filtrate was concentrated under low pressure by use of a rotary evaporator device at 40°C to acquire the crude ethanol extract. Both CPP and ethanol extract were kept in airtight food‐grade containers in controlled laboratory conditions at the Nutrition Lab, Lab no: 2024/11/165, until further experimental use.

2.1.2. Proximate Composition of C. sativus Peel Powder

The proximate content of the CPP was performed using the standard procedures of AOAC (2019). The moisture content in the samples was calculated by drying samples in an oven at the temperature of 150°C until a constant weight was reached using (Method no: 925.10). The ash content was measured by burning the sample in a muffle furnace at the temperature of 550°C up to a constant weight (Method no: 923.03) Crude protein was estimated by nitrogen to protein ratio factor of 6.25 using nitrogen to measure the same in a muffle furnace under the temperature of 550°C (Method no: 960.52). The sequential acid and alkali digestion (Method no: 962.09) was used to analyze the crude fiber content, and Soxhlet extraction petroleum ether as the solvent was used to analyze the crude fat. The percentage composition of carbohydrates was determined by difference calculating the difference as mentioned below.

% Carbohydrates = 100 – (Moisture + Protein + Fat + Fiber + Ash).

2.2. Gas Chromatography–Mass Spectroscopic (GC–MS) Analysis of C. Sativus Peel

The methanolic extract of CPP was examined in the Shimadzu GCMS‐QP 2010 system using a DBI (30 m x 0.25 mm i.d., 0.25 um film thickness) capillary column. Helium was used as the carrier gas, and the flow rate was 0.7 mL/min. The programmed temperature of the oven was set at 70°C (5 min) and then at 180°C–260°C at 3°C/min and a final temperature of 280°C (2°C/min) and a holding time of 5 min. The injector and detector were maintained at 280 and 290°C, respectively, with a split ratio of 3:1. A portion of 1 mL of methanolic was taken out for examination.

2.3. Antioxidant Activity

2.3.1. Sequential Extraction on Aqueous and Ethanolic Solvents

Antioxidant‐rich extracts of the powdered cucumber peel (C. sativus L.) were obtained in two solvents, distilled water and 95% ethanol, in accordance with Shamim et al. (2025). The powdered samples were mixed with each solvent with the solid‐to‐solvent ratio of 1:10 (w/v) and homogenized for 5–6 h using an orbital shaker (Model no: BSOT‐604). The mixtures were then kept overnight at room temperature to ensure maximum extraction of bioactive compounds. After that, the solutions were filtered on Whatman No. 1 filter paper, and the filtrates were concentrated using a rotary evaporator (Model: RE202) at a temperature of 40°C. The crude extracts obtained were submitted to antioxidant tests. Total phenolic content (TPC) was estimated according to the modified Folin–Ciocalteu method, and the results were expressed as milligrams of gallic acid equivalent per gram of extract (mg GAE/g). The absorbance of extracts was measured using a spectrophotometer (Model no: 823‐0210 P‐2‐R) at a wavelength of 760 nm against a blank, and the antioxidant potential of aqueous and ethanolic extracts of cucumber peel was compared.

2.3.2. The DPPH (2, 2‐diphenyl‐1‐picrylhydrazyl) Test of C. Sativus Peel

The DPPH assay was conducted with the variations on the procedure of Hafs et al., (2017). Ethanol was used to prepare a 0.1 mM solution of DPPH. Two milliliters of extract were added to 2 mL of DPPH solution, and the solution was left to stand in the dark at room temperature for 30 min. The blank was obtained by combining 2.5 mL of extract with 1 mL of methanol. Vitamin C acted as a positive control, and 2.5 mL methanol and 1 mL DPPH solution acted as the negative control, and assimilation was sustained at 518 nm through utilizing UV–Vis Spectrometer (Model no: 823‐0210 P‐2‐R). The formula used in computing the antioxidant activity was:

$$\mathrm{DPPH}\%=\frac{\mathrm{Sample}\mathrm{absorance}-\mathrm{Blank}\mathrm{absorbance}}{\mathrm{Control}\mathrm{absorbance}}\times 100$$

2.3.3. Ferric Reducing Antioxidant Power (FRAP) Assay of C. Sativus Peel

The FRAP assay is based on the antioxidant capacity of an antioxidant, that is, the removal of ferric (Fe³⁺) to ferrous (Fe²⁺) ions by antioxidants (Sainu et al., 2012). FRAP was designed by Benzie and Strain (1996) to measure the reduction of ferric (Fe³⁺) to ferrous (Fe²⁺). In this protocol, 0.1 mL of the sample extract is added to 3 mL of FRAP reagent and left to incubate at 37°C at room temperature (dark) over 30 min frequency was measured as the absorbance at 593 nm and measured in milligrams of Trolox equivalents per gram of dry extract (mg TE/g).

2.3.4. Total Phenolic Content (TPC) of C. Sativus Peel

The Folin–Ciocalteu technique was used to determine TPC (Deng et al., 2013). An extract solution, Folin–Ciocalteu reagent, and sodium carbonate were mixed and incubated for 30 min at room temperature in the dark, and the absorbance was determined at 760 nm. The findings were in the form of mg gallic acid equivalent per gram extract (mg GAE/g).

2.4. Animals

Albino rats (4–5 weeks, 90 to 120 g) were purchased from the Institute of Pharmaceutical Sciences, Bahauddin Zakariya University (BZU), Multan (36 males). The animals were kept in a controlled environmental condition (25±2°C, 55±3% relative humidity, and 12‐h light/dark cycle) in ventilated cages with free access to water. The treatments were commenced after the acclimatization of 1 week on a normal diet. All the experiments were conducted in compliance with the institutional directives regarding the handling and treatment of laboratory animals and had to be authorized by the Ethical Review Committee of BZU, Multan (Approval No: 2024/312).

2.4.1. Diabetes Induction and Dietary Interventions

A single intraperitoneal dose of alloxan monohydrate (150 mg/kg) was used to induce diabetes in rats after the animals had been fed or starved (12–16 h) as reported [31]. After 72 h, fasting blood glucose levels above 250 mg/dL in rats were considered diabetic and used in the study. The complete treatment plan is mentioned in Table 1.

TABLE 1.

Treatment plan for different groups of the study.

Groups	Treatment
Normal rat (NR)	Without disease + standard diet (n = 6)
Diabetic rat (DR)	Disease + standard diet (n = 6)
CPP‐5	Disease + 5grams/100gram cucumber peel powder (n = 6)
CPP‐10	Disease + 10gram/100gram cucumber peel powder (n = 6)
CPE‐5	Disease + 5milliliter/day cucumber peel ethanol extract (n = 6)
CPE‐10	Disease + 10milliliter/day cucumber peel ethanol extract (n = 6)

Group I was the negative control (normal) and was treated with only saline at 28 days, Group II was the positive control (diabetic), and they were treated with no therapy after the alloxan injection. Group III received a dosage of CPP of 5 g/100 kg body weight and Group IV received 10 g/100 g. Group V received CPE 5 mL/day body weight and Group VI received 10 mL/day. All treatments were done daily for 28 days.

2.4.2. Blood Collection Procedure

All rats were anesthetized at the end of the 4‐week experimental period and humanely killed by using overdoses of anesthetic agents as reported [32]. Blood samples were obtained by pericardiocentesis and placed into EDTA‐coated tubes and gel vials to be used in further hematological and biochemical analysis. The organs, such as the hepatic, renal, and sweetbread, were then rinsed off in normal brackish water to remove residual blood and weighed accordingly using a precision balance (GX‐600, Japan) as reported [33, 34]. The serum was separated by centrifugation at 4200 rpm for 10 min to extract the serum, then it was utilized in biochemical tests associated with glucose metabolism and other physiological variables. To study the effects of CPP, extract on the structural evaluation of the organs, the dissected organs were stored in 10% formalin to be examined histopathology by following a procedure as reported [35].

2.4.3. Evaluation of Blood Parameters

Insulin response and fasting blood glucose were assessed with the help of tail vein blood taken out of rats. The glucose level was achieved using the glucose test strips and glucometer (Accu‐Chek(r) Active, Roche Diagnostics, Germany), and the serum insulin content was determined using a rat‐specific ELISA kit (AccuBind(r), Monobind Inc., USA) with the 450 nm read using ELISA microplate reader (BioTek, Winooski, VA, USA)

Liver function tests (LFTs) were also conducted to evaluate the hepatic integrity through the levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and total bilirubin in the serum that are considered as some of the major indicators of liver health and enzyme activity. The quantification of these parameters was done by an ELISA microplate reader (Bio‐Tek, Winooski, VT, USA). The renal function tests (RFTs) were also done to assess the performance of kidneys by analysis of serum urea, creatinine, sodium, and potassium with an automated chemistry analyzer (BS‐240 VET, Mindray, China).

An evaluation of blood lipid profile was done by estimating triglycerides (TG, mg/dL), total cholesterol (TC) (mg/dL), high‐density lipoprotein (mg/dL), low‐density lipoprotein (LDL, mg/dL), and very low‐density lipoprotein (mg/dL) through enzymatic colorimetric‐based procedures, the absorbance being measured at 456 nm. The same analyzer was also used to measure serum protein fractions such as albumin and globulin (g/dL).

The cardiac functioning was assessed by measuring serum troponin‐I levels and nitric oxide using a high‐sensitivity immunoassay analyzer (VIDAS(r)3, bioMérieux, France) to identify any myocardial infringements related to diabetic stress or treatment. Blood collected in EDTA‐containing tubes was analyzed using hematological parameters, such as red blood cell (RBC) count (x10⁶/mL), hemoglobin (Hb, g/dL), hematocrit percent, white blood cell (WBC) count (x10³/mL), and differential leukocyte counts. To measure the effect of treatment on hematological changes in experimental rats, samples were analyzed based on automated hematology analyzer (Sysmex KX‐21N, Japan) [36, 37].

2.5. Histopathology

Liver, kidney, and pancreas were taken off immediately after sacrifice, washed with saline and stored in 10% formalin for 24 h. The tissues were dried, put under paraffin, sectioned at 5 µm, stained with hematoxylin and eosin (H&E), and examined under a microscope to determine the structural and pathological alterations as reported [38]. In this study, a histopathology study was performed qualitatively to assess the structural and cellular alterations in the liver, kidney, and pancreas.

2.6. In Silico Antidiabetic Activity Study

The GC–MS spectrum was used to identify the active phytoconstituents, and as shown in Figure 1 and Table 4, it possessed the active phytoconstituents, which were introduced as ligands into a molecular docking study. The 3D structures of these phytoconstituents could be obtained in structure data format (SDF) in the PubChem database (https://pubchem.ncbi.nlm.nih.gov/). After that the BIOVIA Discovery Studio Visualizer was used to convert the SDF files into PDB format. The energy of the conformers of 3D was minimized in Open Babel, with MMFF94, and polar hydrogen was added to any missing bond of the conformer to address the minimization process; the resulting structures were put in PDBQT format. The polar hydrogen and Kollman charges of the selected receptor protein and phytoconstituents were purified by removing water and the polar hydrogen and Kollman charges. Moreover, the ligand already existing in the protein was removed, and the AD4 atoms (autodock) force field corresponding to autodock vina docking was selected. Lastly, Auto Dock Tools 1.5.7 was used to convert the target protein and store it in PDBQT format [39].

FIGURE 1.

GC/MS chromatogram of C. sativus peel methanol extract bioactive compounds.

TABLE 4.

Compounds identified in plant methanolic extract of C. sativus peel by gas chromatography.

Peak #	R. T	Name	Area %
1	23.601 min	Hexadecanoic acid, methyl ester pentadecanoic acid, 14‐methyl‐, methyl ester	4.50
2	24.291 min	n‐Hexadecenoic acid	2.17
3	26.809 min	9,12‐Octadecadienoic acid (Z, Z)‐, methyl ester methyl 9‐cis,11‐trans‐octadecadienoate	3.32
4	26.935 min	9‐Octadecenoic acid, methyl ester, (E)‐	10.47
5	27.062 min	11‐Octadecenoic acid, methyl ester	1.78
6	27.130 min	9,12,15‐Octadecatrienoic acid, methyl ester, (Z, Z, Z)‐	1.28
7	27.421 min	Methyl stearate	1.92
8	27.509 min	9,12‐Octadecadienoic acid (Z, Z)‐, 10E,12Z‐octadecadienoic acid	1.24
9	27.635 min	9‐Octadecenoic acid, (E)‐, 9‐octadecenoic acid, cis‐vaccenic acid	13.28
10	28.053 min	Oleic acid, octadecanoic acid	3.21

Docking using AutoDock Vina was done with the help of PDBQT files of target receptors and phytochemicals, in a grid box of size 40×40×40 centered at the coordinates x = −8.186, y = 9.463, and z = −18.667, where α‐amylase binds, and the grid spacing is 0.375 A, so that the catalytic site residues lie within the grid box. The binding complex that had the most favorable energy, which is represented by a lower value of kcal/mol, was picked for the analysis. The interaction qualities and amino acid residues were investigated with the help of the BIOVIA Discovery Studio Visualizer 2020 (Figure 8), and the target protein was imaged with the help of UCSF CHIMERA (Figure 7).

FIGURE 8.

Interaction mode between the α‐amylase (4W93) catalytic site and phytoconstituents from C. sativus peel.

FIGURE 7.

Visualization of active amino acid site residue of target protein α‐amylase.

2.7. Statistical Analysis

The data were processed by the STATISTIX 8.1 software, and all experiments were performed in triplicate, presented as mean± SD. To determine the statistically significant differences between the groups, a two‐way ANOVA and post‐hoc test (based on the Tukey method) were implemented at a 0.05% significant level. Data were screened by using statical criteria to find outliers if they existed.

3. Result and Discussion

3.1. Proximate Analysis of C. Sativus Peel and Physiochemical Composition of C. Sativus Peel

Results from Table 2 showed that C. sativus peel nutritional profile revealed that it can be used in the management of diabetes, high crude protein (26.9%), high crude fiber (8.96%), moderate ash (7.63%), and low crude fat (1.49%). The content of moisture (20.8%), along with carbohydrates (34.22%).

TABLE 2.

Proximate composition of C. sativus L. peel.

Proximate composition	Mean value ± S.D
Ash content	7.63 ± 0.933
Moisture content	20.8 ± 0.892
Crude protein	26.9 ± 0.042
Crude fat	1.49 ± 0.954
Crude fiber	8.96 ± 0.833
CHO	34.22 ± 0.022

The findings that cucumber peel contains essential minerals, such as magnesium, potassium, and calcium, which contribute to improved glucose metabolism. Reported data [40] suggested strategies for β‐cell survival in the pancreas and highlighted that plant‐derived compounds increase β‐cell survival in the pancreas [41], which is in line with the protein composition found in cucumber peel. In contrast, [42] highlighted that low fat levels help alleviate insulin resistance, whereas [43] reported that high fiber and complex carbohydrates in plant by‐products help to delay glucose absorption, regulate blood sugar after ingestion, and improve gut health. All the discussion about the contents of food to improve the glucose utilization and alleviation of the insulin resistance is consistent with the nutritional composition of CPP in the present study.

The extracts of ethanol and distilled water are statistically significant (p < 0.05). The antioxidant activity of C. sativus peel extracts showed significant variation in different solvents and was presented in Table 3. Diphenyl‐1‐pyrrolopiperidine radical scavenging assay showed higher activity in the ethanol extract (8.96 ±0.933) than that of distilled water extract (8.10±0.853). In addition, the TPC values were also higher in ethanol extract (22.98 ± 0.984 was a better solvent for phenolic compounds extraction. The ferric reducing activity was about the same in the two solvents in the FRAP assay and was 0.15 ± 0.003 mmol/g in ethanol and 0.04±0.002 mmol/g distilled water extracts, respectively, indicating that the type of solvent used had little impact on ferric ion reduction.

TABLE 3.

Comparison test of DPPH, ferric reducing antioxidant power (FRAP), and total phenolic content (TPC) for solvents.

Solvent	DPPH (g/mL)	FRAP (mmol/g)	TPC (mmol/g)
Ethanol	8.96 ± 0.933	0.15 ± 0.003	22.98 ± 0.984
Distilled water	8.10 ± 0.853	0.04 ± 0.002	13.32 ± 0.843

Abbreviations: DPPH, 2,2‐diphenyl‐1‐picrylhydrazyl; TRAP, ferric reducing antioxidant power; TPC, total phenolic content.

The C. sativus peel extracts exhibited different antioxidant activities based on solvent type, with ethanolic extract exhibiting better DPPH radical scavenging activity and a higher TPC [44]. This increase of activity can be correlated to the improved solubility of phenolic and flavonoid compounds in ethanol [45, 46], corroborating their capability to lower oxidative stress and improve the β‐cell function. Overall, the potent activity exerted by the ethanolic extract in the DPPH and TPC assays shows its therapeutic potential against diabetes‐induced oxidative stress.

3.2. Gas Chromatography–Mass Spectroscopic (GC–MS) Analysis of C. Sativus Peel

Figure 1 showed that GC–MS analysis of CPP extract revealed the presence of several bioactive fatty acids and esters. Table 4 showed that cis‐vaccenic acid (13.28%) and 9‐octadecenoic acid, methyl ester (10.47%), the two predominant substances, were linked to anti‐inflammatory, hypocholesterolemia, and cardioprotective effects. Although the linoleic and linoleic acid derivatives (5.84) exhibited antidiabetic, anti‐inflammatory, and anticancer effects, the palmitic acid derivatives (6.67% combined) presented antioxidant and antibacterial action. Methyl stearate and oleic/stearic acid derivatives are other molecules that have been discovered and contribute to metabolic control and immunological regulation. Altogether the results indicate that cucumber peel is a promising source of valuable bioactive compounds that have a potential application in the medical and nutraceutical field.

Antioxidant profile, the GC–MS analysis revealed the presence of important fatty acids in the cucumber peel, like oleic, linoleic, and vaccenic acids. The fatty acids are linked to anti‐inflammatory, antioxidant, and hypolipidemic effects, which help to increase metabolism in diabetic models in general. The family members of the Cucurbitaceae are also reported to have antimicrobial [47] and antidiabetic properties [48] and confirm the therapeutic potential of cucumber peel constituents. These results are in line with the hypothesis that the bioactive lipids, along with flavonoids and phenolics, synergistically re‐establish metabolic homeostasis in diabetes [49, 50]. The current study did not include validation metrics such as repeatability, precision, analytical sensitivity, and specificity, which are essential for ensuring the robustness and reproducibility of the results in GC–MS profiling of C. sativus peel [68]. To strengthen the findings, future studies will include these validation parameters, and reference to ICH Q2(R2) guidelines will be followed for comprehensive method validation.

3.3. Effect of C. Sativus Peel on Fasting Blood Glucose (mg/L)

Figure 2 data show highly significant differences in fasting blood sugar (FBS) levels among treatments at all time points (p < 0.001). The normal control (NR) group maintained the lowest FBS values, ranging from approximately 91.7 to 97.0 mg/dL across days, while the DR had the highest FBS, ranging from 320.3 to 364.7 mg/dL. Treatment groups CPP‐5 and CPP‐10 showed intermediate FBS values (e.g., on day 7: 304.7 and 294.7 mg/dL, respectively), with the 10 g doses generally producing lower blood sugar than the 5 g, indicating a dose‐dependent effect. Additionally, CPE‐5 and CPE‐10 had progressively lower FBS levels (e.g., on day 28: 190.0 and 161.0 mg/dL, respectively).

FIGURE 2.

Effect of C. sativus peel on fasting blood glucose (mg/L).

The administration of cucumber peel has demonstrated a potent hypoglycemic effect, significantly reducing fasting blood glucose levels in DRs. The effect has been attributed to the presence of bioactive compounds in it (flavonoids, phenols, and saponins), which improve insulin secretion, enhance glucose metabolism, and inhibit the enzymes that digest carbohydrates [51]. The findings are supported by recent studies, which indicated that the extract of cucumber peel is also useful in the enhancement of glycemic control in DRs produced by alloxan [52].

3.4. Effect of C. Sativus Peel on Insulin (U/mL)

Statistical analysis of insulin response across days and treatments shows that the normal rat (NR) group consistently exhibited the highest mean insulin levels, ranging from 13.33 ± 0.15 to 13.60 ± 0.10 μIU/mL, while the DR group maintained the lowest values, decreasing from 3.83 ± 0.15 to 2.90 ± 0.26 μIU/mL by day 28 (p< 0.001), as shown in Figure 3. The intervention groups displayed an increasing trend in insulin response over time; for example, CPP‐10 increased from 4.03 ± 0.15 at baseline to 9.40 ± 0.20 μIU/mL on day 28 and CPE‐10 from 4.53 ± 0.25 to 12.30 ± 0.20 μIU/mL.

FIGURE 3.

Effect of C. sativus peel on insulin response (U/mL). Each group consists of six animals.

Serum insulin concentrations in DRs were significantly enhanced with C. sativus peel extract, implying a regenerative effect on pancreatic β‐cells. The bioactive compounds, specifically flavonoids and polyphenols contribute to increasing the level of insulin by eliminating oxidative stress on the pancreatic β‐cells and keeping them structurally and functionally intact [53]. Furthermore, the compounds can enhance peripheral tissue insulin sensitivity by acting on glucose transporters and decreasing inflammatory substances [54]. Based on the data of the current study, it can be speculated that C. sativus therapy enhanced the insulin‐responsiveness, strengthening our argument of possible use of C. sativus as a natural therapeutic agent in the management of diabetes.

Data are presented as mean ± SD. Statistical analysis was performed using two‐way ANOVA (treatment × time) followed by Tukey's post hoc multiple‐comparison test. ns = non‐significant, * = significant (p < 0.05), * = highly significant (p < 0.01). Means sharing the same superscript letter within columns are not significantly different.

3.5. Effect of C. sativus Peel on Histopathological Examination of Pancreas of Diabetic Rats

Figure 4 showed that the negative control group had normal histological structure, with no degeneration, necrosis or cellular infiltration, which is a healthy structure. Conversely, the DC group had high levels of pathological abnormalities that included structural disorganization, cellular damage, and degenerative alteration, which were related to diabetic states caused by alloxan. CPP and cucumber peel ethanol extract (CPE) exhibited a dose‐efficient protection. In lower dosages (5 g/100 g and 5 mL), the two CPP and CE were more successful in restoring tissue shape and lowering cellular damage, whereas higher dosages (10 mL) demonstrated more prominent effects, such as near‐normal architecture, less degeneration, and higher tissue integrity. These results show that the cucumber peel, powder, and ethanol extract possess good antioxidant and antidiabetic properties, and the higher the dose, the higher the results.

FIGURE 4.

Histopathological examination of pancreas sections of rats. Each group consisted of three animals for histopathology slides where slides were prepared in triplicate (3×3 = 9). One of the best presentation of the slice of each group was selected. (A) Normal rat, (B) diabetic rat, (C) cucumber peel powder 5 g/100 g, (D) cucumber peel powder 10 g/100 g, (E) cucumber peel extract 5 mL, and (F) cucumber peel extract 10 mL.

There are no histological studies of cucumber peel, and hence, comparison with other representatives of the Cucurbitaceae family gives context. Cucumber peel serves to preserve the morphology of the islets and the health of the pancreas, which can be explained by its abundance of flavonoids, polyphenols, and polysaccharides, which alleviate oxidative stress, stabilize the cell membrane, and regenerate β‐cells [55].

3.6. Effect of C. Sativus Peel on Hematological Profile of Diabetic Rats

All the hematological data of diabetic, control and all treatment groups are shown in Table 5. The RBC count showed a statistically significant difference among the groups (p < 0.05). The disease control group (DR) exhibited a marked reduction in RBC count (6.62 ± 0.31 × 10⁶/µL) compared to the normal rats (NR: 7.39 ± 0.38 × 10⁶/µL), indicating anemia associated with diabetes mellitus due to oxidative stress and hemolysis. Treatment with both C. sativus peel powder (CPP) and ethanol extract (CPE) showed a gradual improvement in RBC values. The CPE‐10 group (7.25 ± 0.35 × 10⁶/µL) showed near‐normal RBC levels, suggesting a restorative effect on erythropoiesis and red cell membrane integrity. Hemoglobin concentration followed a similar pattern, with a non‐significant difference among groups, but numerically lower Hb levels in the DRs (13.19 ± 0.42 g/dL) than in the normal group (14.16 ± 0.64 g/dL). The increase in Hb levels in the treated groups (13.32–13.97 g/dL).

TABLE 5.

Effect of C. sativus peel on hematological profile of diabetic rats.

Treatment	WBC (×103/µL)	RBC (×106/µL)	Hb (g/dL)	Platelets (×105/µL)	HCT (%)	MCV (fL)	MCH (pg)	MCHC (g/dL)
NR	7.38 ± 0.34c	7.39 ± 0.38a	14.16 ± 0.64a	6.61 ± 0.47c	42.73 ± 1.92a	57.8 ± 2.80a	19.16 ± 1.27b	33.14 ± 1.55b
DR	8.77 ± 0.36a	6.62 ± 0.31b	13.19 ± 0.54d	7.91 ± 0.54a	39.68 ± 1.87d	59.94 ± 2.88b	19.92 ± 1.33d	33.24 ± 0.78d
CPP5	7.69 ± 0.35b c	6.77 ± 0.26c	13.32 ± 0.48b	7.56 ± 0.52a , b	40.81 ± 1.65c,d	60.28 ± 3.43b,c	19.67 ± 1.46a	32.64 ± 1.42c
CPP10	8.31 ± 0.39a , b	6.91 ± 0.29c	13.58 ± 0.51b	7.21 ± 0.49a , b , c	41.31 ± 1.47c,d	59.78 ± 3.26c	19.65 ± 1.14a	32.87 ± 1.38c
CPE5	7.97 ± 0.42a , b , c	7.06 ± 0.33a , b	13.75 ± 0.65c	7.04 ± 0.46a , b , c	41.98 ± 1.37a,b	59.46 ± 3.51d,e	19.48 ± 1.19b	32.75± 1.53c
CPE10	8.55 ± 0.54a	7.25 ± 0.35a , b	13.97 ± 0.57c	6.84 ± 0.41b , c	42.37 ± 1.25a,b	58.44 ± 2.91e	19.27 ± 1.02d	32.97 ± 0.92d
F. ratio	9.11**	3.75*	1.56ns	6.22**	1.35ns	0.46ns	0.30ns	0.10ns

Data are presented as mean ± SD. Statistical analysis was performed using one‐way ANOVA followed by Tukey's post hoc multiple‐comparison test. ns = non‐significant, * = significant (p < 0.05), * = highly significant (p < 0.01). Means sharing the same superscript letter within columns are not significantly different.

The platelet count varied significantly across treatment groups. DRs exhibited marked thrombocytosis (7.91 ± 0.54 × 10⁵/µL), likely driven by inflammatory responses and hyperglycemia‐induced platelet activation. Treatment with CPP and CPE effectively restored platelet counts toward normal levels, with CPE‐10 (6.84 ± 0.41 × 10⁵/µL) demonstrating the most pronounced normalizing effect. This observation indicates potential anti‐inflammatory and vascular protective actions of C. sativus peel. Hematocrit levels were moderately lower in the DC group (39.68 ± 1.87%) compared with the NC (42.73 ± 1.92%), though the difference was not statistically significant. These outcomes correlate with the observation of Olubunmi et al. (2020), who reported a certain ethanolic extracts of cucumber peel enhanced immune responses and mitigated hematological alterations in DRs. Similarly, data reported [51] demonstrated that C. sativus peel extract reduced WBC and neutrophil counts while elevating lymphocyte levels, suggesting strong anti‐inflammatory and antioxidant properties. It has been postulated that hyperglycemia‐induced oxidative stress and glycation damage contribute to anemia and erythrocyte morphological alterations in diabetes.

3.7. Effect of C. Sativus Peel on Lipid Profile

All the lipid profile data of diabetic, control, and all treatment groups are shown in Table 6. All serum biochemical parameters (TC, TG, HDL, VLDL, LDL, and glucose) showed highly significant differences between groups using one‐way ANOVA (p < 0.01). High‐density lipoprotein (HDL) levels were markedly reduced in the DC group (34.87 ± 1.25 mg/dL) compared to the NC rats (40.21 ± 1.25 mg/dL). Treatment with C. sativus peel restored HDL levels in a dose‐dependent manner, where CPP‐5 and CPP‐10 groups recorded 37.77 ± 1.25 mg/dL and 38.93 ± 1.25 mg/dL, respectively, while CPE‐5 and CPE‐10 groups exhibited 38.11 ± 1.25 and 39.57 ± 1.25 mg/dL. The marked elevation of HDL in treated groups, especially in the CPE‐10 group, indicates an enhancement of reverse cholesterol transport and improved antioxidant defense against HDL oxidation.

TABLE 6.

Effect of C. sativus peel on serological analysis.

Treatment	HDL (mg/dl)	LDL (mg/dl)	Total cholesterol (mg/dl)	Triglycerides (mg/dl)	VLDL (mg/dl)
NR	40.213 ± 1.25a	34.610 ± 0.99d	91.26 ± 2.81d	82.21 ± 4.23e	16.443 ± 0.74e
DR	34.870 ± 1.25b	46.233 ± 0.99a	111.49 ± 2.81a	151.93 ± 4.23a	30.387 ± 0.74a
CPP5	37.770 ± 1.25b	42.170 ± 0.99b	107.45 ± 2.81a , b	137.53 ± 4.23b	27.507 ± 0.74b
CPP10	38.930 ± 1.25a , b	40.383 ± 0.99b , c	100.89 ± 2.81b , c	107.89 ± 4.23c , d	21.577 ± 0.74c
CPE5	38.110 ± 1.25a , b	41.560 ± 0.99b , c	103.54 ± 2.81a , b , c	119.34 ± 4.23c	23.870 ± 0.74c
CPE10	39.573 ± 1.25a	38.410 ± 0.99c	96.95 ± 2.81c , d	94.84 ± 4.23d , e	18.970 ± 0.74d
F. ratio	4.55*	30.63**	13.28**	76.39**	97.98**

Data are presented as mean ± SD. Each group consists of six animals. Statistical analysis was performed using one‐way ANOVA followed by Tukey's post hoc multiple‐comparison test. ns = non‐significant, * = significant (p < 0.05), * = highly significant (p < 0.01). Means sharing the same superscript letter within columns are not significantly different.

Low‐density lipoprotein (LDL) levels significantly increased in DRs (46.23 ± 0.99 mg/dL) compared to NCs (34.61 ± 0.99 mg/dL), reflecting oxidative stress and impaired lipid clearance. Treatment with cucumber peel significantly reduced LDL levels across all treated groups, with CPP‐5, CPP‐10, CPE‐5, and CPE‐10 recording 42.17 ± 0.99, 40.38 ± 0.99, 41.56 ± 0.99, and 38.41 ± 0.99 mg/dL, respectively. The CPE‐10 group showed the highest percentage decrease and, therefore, denoted that the ethanolic extract form was more useful in regulating the LDL levels. These results indicate that cucurbitacins and phenolic compounds of C. sativus prevent the activity of hepatic HMG‐CoA reductase and increase the LDL receptor‐mediated uptake, thus reducing the levels of plasma LDL.

TC levels also exhibited a significant rise in DRs (111.49 ± 2.81 mg/dL) compared with NRs (91.26 ± 2.81 mg/dL), indicating a disruption of lipid homeostasis due to insulin deficiency. However, treatment with cucumber peel markedly reduced TC levels to 107.45 ± 2.81 mg/dL in CPP‐5, 100.89 ± 2.81 mg/dL in CPP‐10, 103.54 ± 2.81 mg/dL in CPE‐5, and 96.95 ± 2.81 mg/dL in CPE‐10. Such a substantial normalization of cholesterol in the CPE‐10 group posits that the ethanol extract contained increased bioactive levels that can inhibit intestinal absorption of cholesterol and stimulate its catabolic degradation via the excretion of bile acids.

TG followed a similar pattern, showing a significant increase in DRs (151.93 ± 4.23 mg/dL) compared to NRs (82.21 ± 4.23 mg/dL). Treatment with C. sativus peel reduced TG levels to 137.53 ± 4.23 and 107.89 ± 4.23 mg/dL in the CPP‐5 and CPP‐10 groups, respectively, while the CPE‐5 and CPE‐10 groups recorded 119.34 ± 4.23 and 94.84 ± 4.23 mg/dL. The ethanolic extract again demonstrated superior efficacy, likely due to its higher concentration of polyphenols and flavonoids, which are known to enhance insulin secretion and inhibit hepatic TG synthesis.

Very low‐density lipoprotein (VLDL) levels, which directly correlate with TGs, were significantly elevated in DC rats (30.38 ± 0.74 mg/dL) compared to NCs (16.44 ± 0.74 mg/dL). Administration of cucumber peel led to a dose‐dependent reduction, with values of 27.50 ± 0.74 mg/dL in CPP‐5, 21.57 ± 0.74 mg/dL in CPP‐10, 23.87 ± 0.74 mg/dL in CPE‐5, and 18.97 ± 0.74 mg/dL in CPE‐10. The restoration of VLDL levels in the treated groups indicates that the peel extract improves hepatic lipid metabolism by reducing TG synthesis and VLDL secretion.

Oxidative damage in alloxan‐induced diabetes guides to the destruction of pancreatic β‐cells that result in development of a significant insulin deficiency and inhibition of GLUT‐mediated glucose uptake, contributing to the continued hyperglycemia [56]. The liver reacts by augmenting gluconeogenesis and glycogenolysis, with peripheral tissues moving toward lipolysis and proteolysis encouraging ketone‐body creation and metabolic imbalance [5]. The findings of the current study about the decrease in TC, TG, LDL, and VLDL with the increase of HDL is consistent with the evidence that cucumber peel alleviates diabetic dyslipidemia and reduces cardiovascular risks [57].

3.8. Effect of C. Sativus Peel on Kidney Function Test

All the renal function data for diabetic, control, and all treatment groups are shown in Table 7. The results indicate significant variations in renal function parameters among all groups. Urea levels showed a highly significant difference (F = 101.48, p < 0.01), where the diabetic control (DR) group recorded the highest value (36.75 ± 0.96 mg/dL) compared to the normal control (NR) group (22.93 ± 1.18 mg/dL), reflecting renal impairment due to diabetes. Treatment with C. sativus peel significantly reduced urea levels in a dose‐dependent manner. CPP‐5 (34.45 ± 0.78 mg/dL) showed mild improvement, while CPP‐10 (26.49 ± 1.23 mg/dL) and CPE‐10 (24.26 ± 0.60 mg/dL) exhibited values close to the NC, indicating better renal recovery with higher doses, especially of the ethanolic extract.

TABLE 7.

Effect of C. sativus peel on kidney function test.

Treatment	Urea (mg/dl)	Creatinine (mg/dl)	Sodium (meq/I)	Potassium (meq/I)
NR	22.93±1.18e	0.56±0.02d	123.65±4.28b	4.07±0.19b
DR	36.75±0.96f	0.95±0.04e	147.67±5.32c	5.46±0.15c
CPP‐5	34.45±0.78a	0.86±0.03a	135.85±3.32a	4.40±0.17a
CPP‐10	26.49±1.23c	0.77±0.02b	136.39±2.93a	4.31±0.15a
CPE‐5	29.67±0.80b	0.81±0.03b	133.53±4.47a	4.29±0.07a
CPP‐10	24.26±0.60d	0.65±0.04c	124.89±4.58b	4.23±0.08a,b
F. ratio	101.48**	61.34**	8.89**	2.99**

Data are presented as mean ± SD. Each group consists of six animals. Statistical analysis was performed using one‐way ANOVA followed by Tukey's post hoc multiple‐comparison test. ns = non‐significant, * = significant (p < 0.05), * = highly significant (p < 0.01). Means sharing the same superscript letter within columns are not significantly different.

Creatinine levels also varied significantly (F = 61.34, p < 0.01). The DC showed a marked increase (0.95 ± 0.04 mg/dL) compared to NRs (0.56 ± 0.02 mg/dL). Treatments with cucumber peel reduced creatinine values progressively—CPP‐5 (0.86 ± 0.03 mg/dL), CPP‐10 (0.77 ± 0.02 mg/dL), CPE‐5 (0.81 ± 0.03 mg/dL), and CPE‐10 (0.65 ± 0.04 mg/dL). The lowest creatinine in the CPE‐10 group demonstrates the most effective renal protection among treatments.

Sodium concentration exhibited a significant difference (F = 8.89, p < 0.01), being highest in the DC group (147.67 ± 5.32 meq/L) compared to the NC (123.65 ± 4.28 meq/L). Treatments normalized sodium levels, with CPP‐5 (135.85 ± 3.32 meq/L), CPP‐10 (136.39 ± 2.93 meq/L), and CPE‐5 (133.53 ± 4.47 meq/L) showing near‐normal ranges. The CPE‐10 group (124.89 ± 4.58 meq/L) closely resembled the NRs, suggesting restored electrolyte balance. Potassium levels also differed significantly (F = 2.99, p < 0.05). The DC group had elevated potassium (5.46 ± 0.15 meq/L), while the normal group showed 4.07 ± 0.19 meq/L. All treated groups showed reduced potassium values: CPP‐5 (4.40 ± 0.17 meq/L), CPP‐10 (4.31 ± 0.15 meq/L), CPE‐5 (4.29 ± 0.07 meq/L), and CPE‐10 (4.23 ± 0.08 meq/L).

DRs caused by Alloxan showed the presence of high serum urea and creatinine, which is a sign of diabetic nephropathy caused by hyperglycemia‐induced oxidative stress and inflammation [58]. The decreased urea and creatinine levels indicate increased glomerular filtration, which is probably facilitated by antioxidant polyphenols and flavonoids that decrease the ROS and inflammation [59]. Such results are in line with the reports on other species of the Cucurbitaceae family, where bioactive compounds reduced nephropathy through the regulation of oxidative stress and fibrosis [60].

3.9. Effect of C. sativus Peel on Histopathological Examination of Kidney of Diabetic Rats

The histopathological examination of the renal tissues showed that significant differences among them. The morphology of normal renal glomeruli, Bowman gaps, and tubules was intact, and the renal anatomy was normal. Figure 5 showed that the positive control showed considerable renal injury, such as glomerular atrophy, tubular necrosis, interstitial inflammation, and vascular congestion, demonstrating that alloxan had induced nephropathy. Treatment with CPP‐5 provided partial protection, reduces necrosis and vascular congestion, with some remaining tubular degradation. CPP‐10 was associated with increased nephroprotection, virtually unchanged glomeruli, smaller Bowman gaps, and slight inflammatory changes. The dose‐dependent protection of diabetic kidney damage was evident in CPP.

FIGURE 5.

Histopathological examination of kidney sections of rats. Each group consisted of three animals for histopathology slides, where slides were prepared in triplicate (3×3 = 9). One of the best presentation of the slice of each group was selected. (A) Normal rat, (B) diabetic rat, (C) cucumber peel powder 5 g/100 g, (D) cucumber peel powder 10 g/100 g, (E) cucumber peel extract 5 mL, and (F) cucumber peel extract 10 mL.

The alloxan‐induced DRs showed serious renal injury, such as glomerular atrophy, tubular necrosis, and vascular congestion, which were in line with the nephrotoxicity and oxidative stress caused by hyperglycemia [61]. Although cucumber peel does not have any previous histological data, other Cucurbitaceae have been shown to have similar nephroprotective effects. Pumpkin extract enhanced glomerular integrity by preserving renal function [62], whereas the rind extract of watermelon alleviated necrosis and vascular congestion in DRs [63].

3.10. Effect of C. Sativus Peel on Liver Function Test

All the data of LFT of diabetic, control, and all treatment groups are shown in Table 8. One‐way ANOVA showed a highly significant difference in all hepatic enzymes (AST, ALT, and ALP) among groups (p < 0.01). Post hoc analysis confirmed that the treatments with CPP and extract, particularly at higher doses, were effective in reducing increased enzyme activities to normal values as compared to the DC group. ALP activity was markedly elevated in the diabetic control (DR) group (230.17 ± 7.23 U/L) compared to the normal control (NR) group (141.67 ± 7.23 U/L), indicating hepatic stress. Among the treated groups, a dose‐dependent reduction was observed. CPP5 (212.67 ± 7.23 U/L) showed mild improvement, while CPP10 (184.66 ± 7.23 U/L) and CPE10 (165.18 ± 7.23 U/L) displayed substantial decreases, approaching near‐normal values, suggesting better hepatoprotective potential at higher doses. Alanine aminotransferase (ALT) levels also increased significantly in the diabetic group (63.26 ± 1.99 U/L) compared to NRs (34.16 ± 1.99 U/L). Treatment with cucumber peel formulations reduced these levels notably. CPP5 (59.17 ± 1.99 U/L) and CPE5 (56.14 ± 1.99 U/L) showed moderate improvement, whereas CPP10 (52.65 ± 1.99 U/L) and CPE10 (45.78 ± 1.99 U/L) demonstrated greater normalization of liver enzyme activity, with CPE10 being most effective.

TABLE 8.

Effect of C. sativus peel on LFT.

Treatment	ALP (U/L)	ALT (U/L)	AST (U/L)	Bilirubin (mg/dl)
NR	141.67 ± 7.23e	34.16 ± 1.99d	65.39 ± 3.27e	0.27 ± 0.01f
DR	230.17 ± 7.23a	63.26 ± 1.99a	129.78 ± 3.27a	0.66 ± 0.01a
CPP5	212.67 ± 7.23a , b	59.17 ± 1.99a , b	101.18 ± 3.27b	0.54 ± 0.01b
CPP10	184.66 ± 7.23c , d	52.65 ± 1.99b	86.44 ± 3.27c , d	0.39 ± 0.01d
CPE5	196.84 ± 7.23b , c	56.14 ± 1.99b	91.98 ± 3.27b , c	0.47 ± 0.01c
CPE10	165.18 ± 7.23d , e	45.78 ± 1.99c	77.23 ± 3.27d	0.34 ± 0.01e
F. ratio	39.34**	55.90**	92.35**	278.45**

Data are presented as mean ± SD. Each group consists of six animals. Statistical analysis was performed using one‐way ANOVA followed by Tukey's post hoc multiple‐comparison test. ns = non‐significant, * = significant (p < 0.05), * = highly significant (p < 0.01). Means sharing the same superscript letter within columns are not significantly different.

Aspartate aminotransferase (AST) followed a similar trend, with DC rats showing a significant increase (129.78 ± 3.27 U/L) relative to the normal group (65.39 ± 3.27 U/L). CPP5 (101.18 ± 3.27 U/L) and CPE5 (91.98 ± 3.27 U/L) treatments reduced AST activity moderately, while CPP10 (86.44 ± 3.27 U/L) and CPE10 (77.23 ± 3.27 U/L) exhibited marked restoration toward normal values, indicating dose‐dependent hepatoprotection. Bilirubin concentration, another key indicator of liver function, showed a sharp rise in DRs (0.66 ± 0.01 mg/dL) compared to NCs (0.27 ± 0.01 mg/dL). Both powder and extract treatments reduced bilirubin levels significantly: CPP5 (0.54 ± 0.01 mg/dL), CPE5 (0.47 ± 0.01 mg/dL), CPP10 (0.39 ± 0.01 mg/dL), and CPE10 (0.34 ± 0.01 mg/dL).

Alloxan‐induced DRs also had increased AST, ALT, ALP, and bilirubin, which indicated liver dysfunction resulting from oxidative stress and hyperglycemia [64]. Administration of cucumber peel ethanol extracts, especially CPE‐10, significantly improved these parameters and showed good hepatoprotective potential. The activity has been attributed to flavonoids, phenolics, and cucurbitacin, which increase antioxidant defense and reduce lipid peroxidation.

3.11. Effect of C. sativus Peel on Histopathological Examination of Liver of Diabetic Rats

Histopathological analysis of liver sections showed that liver sections in the negative control group contained normal hepatic architecture, whereas the control diabetic group had severe degeneration, vacuolar changes, sinusoidal dilation, and necrosis of the liver because of alloxan toxicity. Figure 6 showed that the CPP and extract (CPE) reduced liver damage in a dose‐sensitive way. CPP 5 g/100 g had minimal effects, whereas CPP 10 g/100 g had a more effective consequence in terms of hepatic structure repair. Likewise, CPE offered superior hepatoprotection compared to CPP, and the 10 mL/kg extract group showed nearly normal histology, which suggests superior protective effect.

FIGURE 6.

Histopathological examination of liver sections of rats. Each group consisted of three animals for histopathology slides, where slides were prepared in triplicate (3×3 = 9). One of the best presentation of the slice of each group was selected. (A) Normal rat, (B) diabetic rat, (C) cucumber peel powder 5 g/100 g, (D) cucumber peel powder 10 g/100 g, (E) cucumber peel extract 5 mL, and (F) cucumber peel extract 10 mL.

Other plant peels have been shown to have similar hepatoprotective effects, with pumpkin peel polysaccharides decreasing necrosis and increasing antioxidant activity and watermelon rind extract improving hepatic architecture in DRs [65]. Antidiabetic effects have also been observed with cucumber pulp to enhance liver functioning and to decrease vacuolization [66]. Nevertheless, the extract of cucumber peel exhibited greater histological improvements in the present study as shown in Figure 6 due to abundant flavonoids and phenolics in contrast to the pulp.

3.12. Effect of C. Sativus Peel on Cardiac Markers of Diabetic Rats

Cardiac markers data for diabetic, control, and all treatment groups are shown in Table 9. Nitric oxide levels were markedly increased in the diabetic control (DR) group (51.380 ± 1.50 µmol/L) compared to the normal control (NR) group (29.390 ± 1.50 µmol/L), reflecting elevated oxidative and inflammatory activity associated with diabetic cardiac stress. Treatments with cucumber peel formulations demonstrated a dose‐dependent reduction in NO concentration. CPP5 (46.107 ± 1.50 µmol/L) and CPE5 (43.710 ± 1.50 µmol/L) showed partial improvement, while CPP10 (39.560 ± 1.50 µmol/L) and CPE10 (34.680 ± 1.50 µmol/L) produced stronger reductions, approaching near‐normal values, indicating better modulation of nitric oxide production at higher doses.

TABLE 9.

Effect of C. sativus peel on cardiac marker.

Treatment	Nitric oxide (µmol/L)	Troponin I (ng/ml)
NR	29.390 ± 1.50f	0.040 ± 0.003f
DR	51.380 ± 1.50a	0.170 ± 0.003a
CPP5	46.107 ± 1.50b	0.140 ± 0.003b
CPP10	39.560 ± 1.50c , d	0.080 ± 0.003d
CPE5	43.710 ± 1.50b , c	0.120 ± 0.003c
CPE10	34.680 ± 1.50d , e	0.060 ± 0.003e
F. ratio	56.27**	449.40**

Data are presented as mean ± SD. Each group consists of six animals. Statistical analysis was performed using one‐way ANOVA followed by Tukey's post hoc multiple‐comparison test. ns = non‐significant, * = significant (p < 0.05), * = highly significant (p < 0.01). Means sharing the same superscript letter within columns are not significantly different.

Similarly, troponin I levels—a key marker of cardiac injury—were significantly elevated in DC rats (0.170 ± 0.003 ng/mL) compared to NCs (0.040 ± 0.003 ng/mL). Treatment with CPP and extract significantly reduced these levels. CPP5 (0.140 ± 0.003 ng/mL) and CPE5 (0.120 ± 0.003 ng/mL) treatments demonstrated moderate improvement, while CPP10 (0.080 ± 0.003 ng/mL) and especially CPE10 (0.060 ± 0.003 ng/mL) exhibited marked normalization of Troponin I levels, indicating pronounced protection against cardiac damage.

In diabetes, oxidative stress, chronic inflammation, and impairment of mitochondria are linked to high levels of troponins, which are very sensitive biomarkers of cardiomyocyte injury [67]. These factors cause subclinical myocardial injury and the development of diabetic cardiomyopathy [68, 69]. The fact that the level of troponins reduced significantly in this case suggests that bioactive compounds of cucumber peel, particularly TPC, could help to prevent the damage of cardiac tissues caused by hyperglycemia, which is in line with similar findings [67], where flavonoid and phenolic content in the Citrullus lanatus Rind extract normalized the elevated troponin levels in the cardiac tissue.

Although no prior study was reported on cucumber peel and cardiac troponins, other natural bioactive compounds evidence this mechanism. Polyphenols, flavonoids, and saponins are reported to inhibit oxidative stress, reduce inflammatory cytokines, and maintain mitochondrial activity, thus inhibiting apoptosis and the release of troponin in the cardiomyocytes [70, 71]. The observed cardioprotective effect could therefore be explained by the anti‐inflammatory and antioxidant properties of cucumber peel phytochemicals, particularly polyphenols, which opens the possibility of using the fruit as a natural supplement to decrease the risk of heart disease related to diabetes.

3.13. Effect of C. Sativus Peel on Antioxidant Marker

Oxidative stress marker data for diabetic, control, and all treatment groups are shown in Table 10. The antioxidant parameters, including SOD, CAT, reduced GSH, and MDA, were evaluated in all treatment groups NR, DR, CPP 5 g/100 kg (CPP5), CPP 10 g/100 kg (CPP10), CPE 5 mL (CPE5), and CPE 10 mL (CPE10)—to assess oxidative stress and the protective effects of cucumber peel supplementation. The results demonstrated significant differences among the groups, as reflected by highly significant F‐ratios for all parameters (p < 0.01).

TABLE 10.

Effect of C. sativus peel on antioxidants markers.

Treatment	SOD (U/mg protein)	CAT (U/mg protein)	GSH (µmol/g tissue)	MDA (nmol/ml)
NR	7.950 ± 0.21a	18.180 ± 0.42a	4.1067 ± 0.10a	2.7933 ± 0.09e
DR	4.470 ± 0.21d	11.450 ± 0.42d	2.7400 ± 0.10d	4.6633 ± 0.09a
CPP5	6.490 ± 0.21c	15.930 ± 0.42c	2.9800 ± 0.10c , d	3.8100 ± 0.09b
CPP10	7.310 ± 0.21b	17.050 ± 0.42b , c	3.3867 ± 0.10b	3.2100 ± 0.09c , d
CPE5	6.980 ± 0.21b , c	16.460 ± 0.42b , c	3.1133 ± 0.10b , c	3.4933 ± 0.09b , c
CPE10	7.710 ± 0.21a , b	17.660 ± 0.42a , b	3.8700 ± 0.10a	2.9700 ± 0.09d , e
F. ratio	66.93**	65.38**	49.15**	96.61**

Data are presented as mean ± SD. Each group consists of six animals. Statistical analysis was performed using one‐way ANOVA followed by Tukey's post hoc multiple‐comparison test. ns = non‐significant, * = significant (p < 0.05), * = highly significant (p < 0.01). Means sharing the same superscript letter within columns are not significantly different.

SOD activity was markedly reduced in the diabetic group (4.47 ± 0.21 U/mg protein) compared to the NC (7.95 ± 0.21 U/mg protein), indicating excessive oxidative stress and impaired antioxidant defense due to alloxan‐induced diabetes. Supplementation with cucumber peel markedly enhanced SOD levels in a dose‐dependent manner. The CPP5 group showed moderate improvement (6.49 ± 0.21 U/mg), while CPP10 (7.31 ± 0.21 U/mg) and CPE10 (7.71 ± 0.21 U/mg) showed near‐normal restoration of SOD activity. The CPE5 group (6.98 ± 0.21 U/mg) also exhibited a significant increase compared to DC, confirming that CPE, particularly at higher doses, effectively boosts endogenous antioxidant enzyme activity and reduces oxidative stress.

Similarly, CAT activity followed a parallel trend. The DRs had significantly decreased CAT levels (11.45 ± 0.42 U/mg protein) relative to NRs (18.18 ± 0.42 U/mg protein), reflecting reduced enzymatic defense against hydrogen peroxide accumulation. Treatment with CPP and extract significantly elevated CAT activity. CPP5 (15.93 ± 0.42), CPP10 (17.05 ± 0.42), CPE5 (16.46 ± 0.42), and CPE10 (17.66 ± 0.42) all showed substantial improvements, with CPE10. The difference among groups was statistically significant (F‐ratio = 65.38**).

Reduced GSH, a vital non‐enzymatic antioxidant, was also depleted in DRs (2.74 ± 0.10 µmol/g tissue) compared to NC (4.11 ± 0.10 µmol/g tissue), indicating severe oxidative stress. Treatment with cucumber peel formulations significantly elevated GSH levels, where CPP5 (2.98 ± 0.10), CPP10 (3.39 ± 0.10), CPE5 (3.11 ± 0.10), and CPE10 (3.87 ± 0.10) all demonstrated considerable recovery, with the CPE10 group nearly reaching normal values. In contrast, MDA, a marker of lipid peroxidation, was markedly elevated in the diabetic group (4.66 ± 0.09 nmol/ml) compared to the NC (2.79 ± 0.09 nmol/ml), indicating increased oxidative membrane damage. Treatment with CPP and extract significantly reduced MDA levels, with the most notable reduction in the CPE10 group (2.97 ± 0.09 nmol/ml), followed by CPP10 (3.21 ± 0.09) and CPE5 (3.49 ± 0.09), while CPP5 (3.81 ± 0.09) showed moderate improvement. The significant F‐ratio (96.61) confirmed the substantial impact of treatment in reducing lipid peroxidation.

Diabetes mellitus is related to a persistent increase in glucose, which facilitates the overproduction of ROS and decreases the capacity to counter the antioxidant defense system in the body. Such a disproportion between the oxidants and the antioxidants adds a lot to the oxidative stress and cell damage. Oxidative stress has a major role in the pathophysiology of diabetic cardiomyopathy [72]. The enzymatic antioxidants include CAT and SOD, which are essential in the process of neutralizing the presence of free radicals and upholding oxidative balance [73]. Nonetheless, due to the diabetic condition, their activity is significantly slowed down, resulting in the accumulation of superoxide anions and hydrogen peroxide [74], which damages the cell membranes, proteins, and DNA. Enzymatic antioxidants, non‐enzymatic such as reduced GSH molecules, also play a vital role as critical intracellular antioxidants that neutralize reactive metabolites and maintain redox equilibrium. The loss of GSH during diabetes signals loss of detoxification efficiency and exposure to oxidative stress to a larger degree [75]. Conversely, high MDA, which is a lipid peroxidation product, serves as a key marker of oxidative membrane damage and confirms enhanced oxidative stress in diabetic tissues. Treatment with different doses of C. sativus maintained these antioxidant and prooxidant markers and protected the complications of diabetes, possibly due to its polyphenolic content.

3.14. Effect of C. Sativus Peel on Protein of Diabetic Rats

All data related to total protein are shown in Table 11. The total protein concentration was slightly decreased in the DC group (6.82 ± 0.22 g/dl) compared to the NC (6.97 ± 0.22 g/dl), indicating mild hepatic dysfunction due to alloxan‐induced diabetes. Supplementation with CPP and extract improved total protein levels, with CPP5 (6.88 ± 0.22 g/dl), CPP10 (6.96 ± 0.22 g/dl), CPE5 (6.97 ± 0.22 g/dl), and particularly CPE10 (7.01 ± 0.22 g/dl) showing values close to or slightly higher than the normal group.

TABLE 11.

Effect of C. sativus peel on blood protein.

Treatment	Total protein (g/dl)	Albumin (g/dl)	Globulin (g/dl)	A/G ratio
NR	6.970 ± 0.22	3.790 ± 0.13	3.1767 ± 0.12	1.1933 ± 0.03a
DR	6.823 ± 0.22	3.510 ± 0.13	3.3133 ± 0.12	1.0600 ± 0.03b
CPP5	6.880 ± 0.22	3.640 ± 0.13	3.2400 ± 0.12	1.1233 ± 0.03a , b
CPP10	6.960 ± 0.22	3.707 ± 0.13	3.2500 ± 0.12	1.1400 ± 0.03a , b
CPE5	6.970 ± 0.22	3.780 ± 0.13	3.1900 ± 0.12	1.1833 ± 0.03a
CPE10	7.010 ± 0.22	3.860 ± 0.13	3.1500 ± 0.12	1.2267 ± 0.03a
F. ratio	0.20ns	1.79ns	0.50ns	6.89**

Data are presented as mean ± SD. Each group consists of six animals. Statistical analysis was performed using one‐way ANOVA followed by Tukey's post hoc multiple‐comparison test. ns = non‐significant, * = significant (p < 0.05), * = highly significant (p < 0.01). Means sharing the same superscript letter within a column are not significantly different.

Serum albumin levels followed a similar trend, where the NC (3.79 ± 0.13 g/dl) showed higher albumin compared to the diabetic group (3.51 ± 0.13 g/dl), reflecting reduced liver function and impaired protein metabolism under hyperglycemic conditions. Treatment with CPP5 (3.64 ± 0.13 g/dl), CPP10 (3.71 ± 0.13 g/dl), CPE5 (3.78 ± 0.13 g/dl), and CPE10 (3.86 ± 0.13 g/dl) resulted in gradual improvement, with the CPE10 group demonstrating the highest albumin value, comparable to the NC. Globulin concentrations remained relatively stable among all groups, ranging from 3.15 ± 0.12 to 3.31 ± 0.12 g/dl. The diabetic group (3.31 ± 0.12 g/dl) showed a slight elevation compared to NRs (3.18 ± 0.12 g/dl), which could be attributed to mild inflammatory or immune responses associated with diabetes. The treated groups—CPP5 (3.24 ± 0.12 g/dl), CPP10 (3.25 ± 0.12 g/dl), CPE5 (3.19 ± 0.12 g/dl), and CPE10 (3.15 ± 0.12 g/dl).

The albumin‐to‐globulin (A/G) ratio, a sensitive indicator of liver function and protein balance, showed the most notable change. The NC group recorded a ratio of 1.19 ± 0.03, while the DC showed a significant decline to 1.06 ± 0.03, indicating liver impairment and protein imbalance due to alloxan toxicity. Treatment with CPP5 (1.12 ± 0.03), CPP10 (1.14 ± 0.03), CPE5 (1.18 ± 0.03), and CPE10 (1.23 ± 0.03) progressively improved the A/G ratio, with CPE10 restoring it to near‐normal levels.

Hypoalbuminemia and the decrease in total proteins of DRs indicate the effects of hyperglycemia‐induced oxidative stress on impaired hepatic protein synthesis, increased protein breakdown, and urine protein excretion [76]. Phenolics, flavonoids, and fibers enhanced by treatment with C. sativus peel improved albumin and total protein, protecting liver tissue and improving protein synthesis [77]. Other interventions made with plant‐based products also reinstated serum protein profiles and liver biomarkers in diabetic models [78]. This improved A/G ratio also implies that cucumber peel promotes protein synthesis and controls diabetes‐associated inflammation. Variability across experimental batches and days is acknowledged, and its potential impact due to the experimental conditions, environmental changes, and sample handling on reproducibility is particularly when working with biological samples. However, a more detailed statistical analysis is warranted to assess the degree to which batch‐to‐batch and day‐to‐day variability may affect the consistency of the results [69, 70]. This analysis will be included in future studies to improve the reliability and reproducibility of the findings.

3.15. Molecular Docking

Molecular docking is essential for predicting where and how drugs and chemicals bind to proteins, helping to understand the binding mechanism better and aiding in the design and discovery of new therapeutic compounds [79, 80]. The docking method was initially validated through docking and re‐docking techniques. An RMSD value of 0.127 Å (< 2) was achieved when the redocked ligand was superimposed on a previous ligand, confirming the validity of the docking process. The 3D visualization of the docking provided data about the binding site, bonding traits, bond length, and binding energy in kcal/mol.

α‐Amylase is a vital enzyme that is present in the salivary and pancreatic secretions. It is an enzyme found naturally, which is crucial in the degrading process of the carbohydrates present in the food, such as starch, into maltose. This process then increases the blood sugar levels following the consumption of meals when the maltose is broken down via the work of the alpha‐glucosidase in the intestine to glucose [81, 82]. Consequently, α‐amylase is believed to be one of the key targets of new antidiabetic drugs [39, 83]. Acarbose is also one such antidiabetic medication that acts by preventing α‐amylase, hence reducing the blood sugar levels following food intake [82]. Nevertheless, the adverse effects of gastrointestinal drugs, including stomach pain, gastric and diarrhea, limit the therapeutic application and patient compliance [39], which points to the necessity of new therapeutic agents. Phytochemicals have also become the topic of interest because of the promising use of the bioactive compounds in the treatment of postprandial hyperglycemia through inhibition of α‐amylase [82].

The docking of phytochemicals from the peel extract of C. sativus peel extract with α‐amylase showed significant binding energies, which indicated that the enzyme should be inhibited, as shown in Figure 7. The results showed that the best binding energy was 9,12,15‐octadecatrienoic acid that had a docking score of −6.00 Kcal/mol, indicating a strong interaction with the enzyme. Other important phytochemicals with a high binding energy were 9,12‐octadecadienoic acid (Z, Z) −5.56 kcal/mol, 9‐18‐carbon acid −5.42 kcal/mol, and cis‐vaccenic acid −5.38 kcal/mol. These were compounds that had positive binding energies with the key residues such as LYS A:200, HIS A:201, and ARG A:195, and increased their high inhibitory potential. On the other hand, the binding energies of Hexadecanoic acid and 11‐Octadecenoic acid were moderate (−5.14 and −5.11 kcal/mol, respectively). The lowest affinity was the methyl stearate with a docking result of −4.91 kcal/mol, meaning that it has a comparatively lower affinity to α‐amylase. These results suggest that C. sativus peel may include bioactive compounds that have potential pharmaceutical potential as antidiabetics, probably have an α‐amylase inhibitive effect. The finding is consistent with other studies done on the antidiabetic properties of C. sativus peel extracts, which were found to have an inhibitory effect on digestive enzymes such as α‐amylase using different in vitro and in silico techniques.

All the phytoconstituents showed the highest binding affinity, ranging from −4.76 to −6.00 kcal/mol against α‐amylase, compared to standard acarbose (−5.5 kcal/mol), as shown in Figure 8 and Table 12.

TABLE 12.

Binding energies (Kcal/mol) of the phytoconstituents of C. sativus peel against α‐amylase.

S.N	PubChem Id	Ligands	Docking score (kcal/mol)	Interaction
1	985	Hexadecanoic acid	−5.14	LYS A:200, HIS A:201, ALA A:198, LEU A:162, THR A:163, HIS A:101, ASP A:300, LEU A:165, TRP A:58, TYR A:62, HIS A:299, ARG A:195, ASP A:197, GLU A:233, ILE A:235, VAL A:234, SER A:199
2	5280450	9,12‐Octadecadienoic acid (Z,Z)	−5.56	ARG A:195, TYR A:62, LEU A:165, ASP A:197, HIS A:299, ALA A:198, ASP A:300, HIS A:101, LEU A:162, THR A:163, TRP A:58, TRP A:59, GLN A:63
3	965	9‐Octadecenoic acid	−5.42	HIS A:305, THR A:163, LEU A:165, GLN A:63, HIS A:101, ASP A:197, LEU A:162, TRP A:59, HIS A:299, ALA A:198, TYR A:62, ARG A:195, TRP A:58, ASP A:300
4	5281127	11‐Octadecenoic acid	−5.11	HIS A:305, TRP A:59, LEU A:165, TRP A:58, LEU A:162, ASP A:300, THR A:163, TYR A:62, GLN A:63, HIS A:299, ASP A:197, ALA A:198, GLU A:233, ARG A:195
5	860	9,12,15‐Octadecatrienoic acid	−6.00	ALA A:198, ASP A:197, HIS A:101, LEU A:162, LEU A:165, HIS A:299, TYR A:62, GLN A:63, TRP A:58, HIS A:305, TRP A:59, ASP A:300, THR A:163, ARG A:195, GLU A:233
6	8201	Methyl stearate	−4.91	ALA A:50, SER A:112, ASN A:53, TYR A:52, ILE A:51, GLN A:63, THR A:163, TRP A:59, LEU A:165, LEU A:162, HIS A:201, ALA A:198, GLU A:233, LYS A:200, VAL A:234, ILE A:235, VAL A:107
7	5282761	cis‐Vaccenic acid	−5.38	TRP A:59, LEU A:165, THR A:163, ASP A:300, TRP A:58, HIS A:299, ASP A:197, TYR A:62, ALA A:198, HIS A:201, SER A:199, GLU A:233, VAL A:234, LYS A:200, ILE A:235, HIS A:101, LEU A:162, GLN A:63
8	445639	Oleic acid	−5.35	TYR A:62, GLN A:63, ARG A:195, ALA A:198, GLU A:233, ASP A:197, LEU A:165, HIS A:299, THR A:163, TRP A:59, HIS A:101, ASP A:300, TRP A:58, LEU A:162
9	5281	Octadecanoic acid	−4.798	VAL A:107, ILE A:51, VAL A:234, GLU A:233, ILE A:235, LYS A:200, ALA A:198, HIS A:201, LEU A:162, THR A:163, LEU A:165, GLN A:63, TRP A:59, TYR A:52, ASN A:53, SER A:112, ALA A:50, VAL A:49, PHE A:119

The bioactive compounds in C. sativus peel, including oleic acid, linoleic acid, and vaccenic acid, play crucial roles in its antidiabetic effects, primarily through antioxidant, anti‐inflammatory, and hypolipidemic activities. Oleic acid, a monounsaturated fatty acid, enhances insulin sensitivity and glucose metabolism by activating the AMPK pathway, promoting glucose uptake, fatty acid oxidation, and lipid reduction in tissues like the liver and skeletal muscles [71, 72]. Linoleic acid, a polyunsaturated fatty acid, reduces oxidative stress and inflammation, protecting pancreatic β‐cells from ROS damage, while vaccenic acid modulates the NF‐κB pathway, alleviating inflammation and insulin resistance [5]. These fatty acids have established therapeutic action in diabetes; however, their role in lipogenesis inhibition, by downregulating lipogenic genes, such as FAS and SREBP‐1c, warrants further investigation to deepen mechanism of therapeuitc action [71]. In silico molecular docking studies revealed (Figure 8) that 9,12,15‐octadecatrienoic acid from C. sativus peel strongly binds to α‐amylase, inhibiting starch digestion [74]. The study could expand to examine the selectivity of these compounds for other glycosidases like α‐glucosidase. Comparing in vivo (rat model) and in vitro (cell‐based assays) results would clarify bioavailability and biotransformation in the body, providing insight into their actual effects in living organisms. Additionally, exploring the synergistic effects of fatty acids, flavonoids, and polyphenols could reveal how their combined actions enhance therapeutic outcomes [75, 76]. In conclusion, further investigations into lipogenesis inhibition, gut microbiome regulation, and molecular docking interactions would strengthen the understanding of the bioactive compounds' roles found in the C. sativus peel in metabolic regulation and for diabetes management.

4. Conclusion

The CPE exhibited a promising antidiabetic effect in fasting blood glucose, lipid profiles, and the repertory of renal and hepatic biomarkers. GC–MS data showed the presence of bioactive phytochemicals, which showed high antioxidant and anti‐inflammatory properties attributed to hepatoprotective, nephroprotective, cardioprotective, and pancreatic tissue preservation activities. These protective actions were also supported by histopathology. Molecular docking studies showed that major compounds, especially the 9,12,15‐octadecatrienoic acid, bind strongly to α‐amylase making the cucumber peel a good natural source of antidiabetic agents.

Author Contributions

Hira Tasleem, Asad Abbas, and Khurram Afzal were involved in the conceptualization and design of the study. Hira Tasleem, Asad Abbas, and Javaria Saeed performed the experimental work and data acquisition. Bipindra Pandey and Waad Alrohily contributed to antimicrobial and biological data analysis. Ali F. Almutairy, Hamoud Alotaibi, Saleh Alfuraih, and Mohammad Mujahid assisted with formal data analysis, validation, and interpretation of physicochemical and characterization results. Mohammad Mujahid and Latifah Al Shammari contributed to visualization and critical data interpretation. Ashfaq Ahmad and Khurram Afzal supervised the study and contributed to project administration. Ashfaq Ahmad also participated in manuscript drafting and critical revision. All authors reviewed, edited, and approved the final version of the manuscript and agree to be accountable for all aspects of the work.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.