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. 2026 Apr 7;46:102570. doi: 10.1016/j.bbrep.2026.102570

Polygonatum sibiricum polysaccharides ameliorate diabetes-induced vascular endothelial injury partly through Nrf2/GPX4 activation

Dongdong Wu a,1, Jing Zhao b,1, Qifan Yang a, Rourou Fang a, Shouzhu Xu a,⁎
PMCID: PMC13091079  PMID: 42004546

Abstract

Diabetes mellitus is a chronic metabolic disorder in which endothelial dysfunction plays a pivotal role in disease progression. Polygonatum sibiricum polysaccharides (PSP) exhibit multiple biological activities, including antioxidant effects, anti-apoptotic action, and regulation of lipid metabolism. However, the mechanisms by which PSP protects against diabetic endothelial injury remain poorly understood. Therefore, this study aimed to elucidate the protective role and underlying mechanisms of PSP in diabetes-induced vascular endothelial injury. In this study, PSP treatment markedly alleviated diabetes-induced vascular endothelial injury, reduced serum TG and LDL levels in streptozotocin (STZ)-induced diabetic rats. Proteomic enrichment analysis revealed that PSP modulates multiple molecular pathways related to oxidative stress, lipid metabolism, and apoptosis. Further experiments showed that PSP treatment restored mitochondrial membrane potential, enhanced cell viability, suppressed Caspase-3 and Bax expression, and upregulated Bcl-2 to attenuate palmitic acid (PA)-induced apoptosis in endothelial cells. Moreover, PSP reduced lipid peroxidation products (ROS and MDA) and upregulated the expression of Nrf2 and GPX4. In conclusion, PSP effectively alleviates diabetes-induced vascular endothelial injury by improving lipid metabolism, inhibiting apoptosis and oxidative stress, partly through activation of the Nrf2/GPX4 pathway. These findings highlight the potential of PSP as a therapeutic agent for diabetes.

Keywords: Polygonatum sibiricum polysaccharides, Diabetes mellitus, Proteomic analysis, Vascular endothelial injury

Highlights

  • •

    PSP alleviates vascular endothelial injury in diabetic rats.

  • •

    PSP improves lipid metabolism and reduces oxidative stress.

  • •

    PSP ameliorates vascular endothelial injury, at least in part, by activating the NRF2/GPX4 signaling pathway.

1. Introduction

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by persistent hyperglycemia, primarily caused by insulin resistance or insufficient insulin secretion [1]. At the same time, diabetic complications are becoming increasingly common in peripheral organs, including the cardiovascular system, kidneys, retina, nervous system, and liver; however, the underlying molecular mechanisms remain poorly understood [[2], [3], [4], [5]]. Diabetic complications involve both macrovascular (e.g., atherosclerosis, coronary artery disease) and microvascular complications (e.g., diabetic nephropathy, retinopathy, and neuropathy) [[6], [7], [8], [9]]. Endothelial dysfunction in the vascular intima plays a central role in the pathogenesis of cardiovascular complications [10], which also represents a key pathological feature of diabetic complications, largely driven by immune inflammation and metabolic imbalance [11,12]. Therefore, maintaining vascular endothelial homeostasis is essential for preventing microvascular complications in diabetes.

Polygonatum sibiricum (PS), a member of the Liliaceae family, is a traditional Chinese medicinal herb widely used in East and South Asia for its diverse therapeutic properties [13,14]. Polygonatum sibiricum polysaccharides (PSP), the major bioactive component of PS, have been reported to enhance stress resistance, delay aging, reduce lipid levels, and exhibit anti-atherosclerotic effects [15]. PSP has been shown to decrease fasting blood glucose, total cholesterol, and triglyceride levels in hyperlipidemic and diabetic animal models. In addition, PSP enhances immune function, suppresses inflammatory cytokine production, and promotes glucose uptake in adipocytes [16]. Furthermore, studies have indicated that aqueous extracts of Polygonatum sibiricum ameliorate hepatic insulin resistance by activating the phosphoinositide-3-kinase/protein kinase B (PI3K/AKT) signaling pathway in mice [17]. However, the precise molecular mechanisms underlying the protective effects of PSP on diabetic endothelial injury remain unclear. Therefore, this study aimed to elucidate the mechanisms by which PSP protects vascular endothelial cells from diabetes-induced injury.

2. Materials and methods

2.1. Reagents

The PSP was purchased from Shaanxi Health Biotechnology Co., Ltd (Xi'an, China, CAT#HYS190914 and CAT#HYS20240603). HUVECs were provided by the Air Force Medical University. Fetal bovine serum (FBS, CAT#SA211.01) and Dulbecco's Modified Eagle Medium (DMEM, CAT#CGM102.05) were sourced from Cellmax (Beijing, China). The Cell Counting Kit-8 (CCK-8, CAT#C0037), bicinchoninic acid (BCA, CAT#P0012S), penicillin-streptomycin (CAT#C0222), MDA (CAT#S0131S), DAPI (CAT#C1006), and JC-1 (CAT#C2003S) were obtained from Beyotime (Shanghai, China). Assay kits for LDL (CAT#A113-1-1), HDL (CAT#A112-2-1), and triglycerides (TG, CAT#A110-2-1) were procured from Nanjing Jiancheng Bioengineering Institute (Nanjing, China). Antibodies for Bax mouse mAb (CAT#YM3619), Bcl-2 rabbit mAb (CAT#YM8002), Nrf2 mouse mAb (CAT#YM4294), GPX4 rabbit pAb (CAT#YN3047), GAPDH mouse mAb (CAT#YM3029), HRP-labeled Goat Anti-Rabbit IgG (H + L) (CAT#RS0002) and HRP-labeled Goat Anti-Mouse IgG (H + L) (CAT#RS0001) were from ImmunoWay Biotechnology Co., Ltd (Jiangsu, China). The Caspase 3 antibody (CAT#9661) was obtained from Cell Signaling Technology, Inc. (USA). ECL luminescence solution (CAT# BF06053S) was purchased from Biodragon (Beijing, China).

2.2. Animals

Male Sprague-Dawley (SD) rats (4 weeks old, weighing 120–140 g) were purchased from the Animal Experiment Center of Xi'an Jiaotong University (Xi'an, China) and housed in the Shaanxi Provincial Key Laboratory of Acupuncture and Medicine under standard laboratory conditions (22 ± 2 °C, 12 h light/dark cycle, with free access to food and water). After a one-week acclimatization period, diabetes was induced by intraperitoneal injection of streptozotocin (STZ; Sigma-Aldrich, St. Louis, MO, USA) at 30 mg/kg body weight for three consecutive days. Control rats received an equivalent volume of saline solution. Successful induction of diabetes was confirmed 72 h after the last injection, when fasting blood glucose levels exceeded 16.7 mmol/L and typical symptoms such as polydipsia, polyphagia, polyuria, and weight loss were observed. Diabetic rats were then randomly divided into three groups (n = 8 per group): (1) model group (diabetic rats without PSP treatment), (2) low-dose PSP group (35 mg/kg PSP), and (3) high-dose PSP group (70 mg/kg PSP). PSP was administered once daily by oral gavage beginning 7 days after STZ injection and continued for 8 weeks. Body weight and fasting blood glucose were monitored weekly. At the end of the treatment period, rats were euthanized, and vascular tissues were harvested for subsequent biochemical, histological, and proteomic analyses. All animal experiments were performed in accordance with institutional guidelines and approved by the Animal Care and Use Committee of Shaanxi University of Chinese Medicine (Ethical Approval No. 202262).

2.3. Tissue preparation and staining

The vascular tissue of the rats was fixed using a 4% paraformaldehyde solution, dehydrated with ethanol, and then embedded in paraffin. Subsequently, the paraffin-embedded tissue was sectioned into slices that were 5 μm thick. These sections were dewaxed using xylene and subsequently washed with ethanol. Hematoxylin staining was performed for 10 min, followed by washing with ethanol and eosin staining for 2 min. After dehydration, clearing, and mounting processes were completed, the stained samples were observed under a microscope.

2.4. Serum lipids analysis

The serum of the rats was extracted for the analysis of TG, LDL, and HDL levels. The measurements were conducted using commercially available assay kits obtained from Nanjing Jiancheng Bioengineering Institute in accordance with the manufacturer's protocols.

2.5. Data-dependent acquisition quantitative proteomic analysis

Vascular tissues were collected from the control, diabetic model, and diabetic model + PSP (70 mg/kg) groups. Protein digestion was performed using a filter-assisted sample preparation method (200 μg per sample). Tryptic peptides were redissolved in 0.1% formic acid (FA) and directly loaded onto a reversed-phase analytical column (Acclaim PepMap® RSLC C18, 2 μm, 100 Å, 50 μm × 15 cm). On the Ultimate 3000 system, mobile phase A consisted of H2O with 0.1% FA and 2% ACN, while mobile phase B consisted of 98% ACN with 0.1% FA. The gradient was programmed as follows: 5% to 45% B over 70 min, 45% to 80% B over the next 5 min, followed by a 15-min hold at 80% B, at a constant flow rate of 300 nL/min. The eluent was ionized using a 2.5 kV nanospray ionization source and analyzed by MS/MS on a Q Exactive HF mass spectrometer (Thermo Fisher Scientific). The instrument operated in data-dependent acquisition (DDA) mode, alternating between full MS and MS/MS scans. Full-scan MS spectra (m/z 400–2000) were acquired at a resolution of 60,000. The top 15 most intense precursor ions were selected for higher-energy collision-induced dissociation (HCD) with a normalized collision energy of 27%. Fragment ions were detected at a resolution of 15,000. The intensity threshold was set at 1 × 105, and the dynamic exclusion time was 20 s. Additional parameters included an automatic gain control (AGC) target of 1 × 106 ions and a fixed first mass of 100 m/z.

Proteomic data were processed and normalized prior to statistical analysis. Differential protein expression was analyzed using the “limma” package in R, with thresholds of |logFC| > 0.75 and p < 0.05. To identify co-expression modules, weighted gene co-expression network analysis (WGCNA) was performed using the “WGCNA” package in R. A soft-thresholding power (β) was selected based on the criterion of approximate scale-free topology (R2 > 0.85). An adjacency matrix was constructed and transformed into a topological overlap matrix (TOM). Modules were identified using dynamic tree cutting with a minimum module size of 30 proteins, followed by module merging at a cut height of 0.25. Key modules associated with experimental groups were identified based on module-trait correlations (p < 0.05). Proteins overlapping between significant WGCNA modules and differentially expressed proteins were considered as candidate mediators of PSP's protective effects on diabetic vascular endothelial injury. Finally, functional enrichment analysis, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, was performed in RStudio to elucidate potential mechanisms of action.

2.6. Cell culture

Human umbilical vein endothelial cells (HUVECs) were cultured in complete DMEM medium supplemented with 10% fetal bovine serum (FBS) and 1% penicillin–streptomycin. Cells in the logarithmic growth phase were selected for subsequent experiments to ensure optimal viability and proliferative activity. Palmitic acid (PA; Sigma, USA), a key inducer of diabetic cell models, plays a crucial role in β-cell dysfunction, insulin resistance, oxidative stress, and inflammation, and is therefore widely used to mimic diabetic conditions in vitro [18,19]. To establish an in vitro model of diabetic vascular endothelial injury, based on preliminary data and in accordance with the protocol described by You et al. [20,21], PA was conjugated to bovine serum albumin (BSA, 10%) in serum-free DMEM prior to cell treatment. The final vehicle concentration (BSA alone) was maintained consistently across all experimental groups, and a vehicle control group (BSA only) was included in all experiments to ensure experimental reliability.

2.7. Cell viability assay

HUVECs were seeded into 96-well plates at a density of 1.5–2.0 × 104 cells per well and cultured at 37 °C in a humidified incubator with 5% CO2. After the cells had adhered uniformly, they were treated with the indicated compounds. Each experimental condition was performed in six replicate wells. Upon completion of the treatment period, the culture medium was removed, and 100 μL of fresh medium containing 10% (v/v) CCK-8 reagent was added to each well. The plates were subsequently incubated at 37 °C for an additional 2 h. The absorbance was measured at 450 nm using a microplate reader (KAIAO, Beijing, China), and cell viability was calculated using the following formula: Cell viability (%)=(OD sample−OD blank)/(OD control−OD blank)*100%.

2.8. Mitochondrial membrane potential (MMP) assay

The MMP was evaluated using the JC-1 dye kit in accordance with the manufacturer's protocol. After 24 h of drug treatment, HUVECs were washed twice with PBS, and subsequently incubated with JC-1 for 20 min at 37 °C in the dark. Fluorescence images were acquired using a confocal laser scanning microscope (Olympus Corporation, at 200 × magnification), and quantitative image analysis was performed using ImageJ software (version 1.41).

2.9. Reactive oxygen species (ROS) activity assay

ROS levels in HUVECs were evaluated using the Reactive Oxygen Species Assay Kit. Following 24 h of drug treatment, HUVECs were incubated with 10 μM DCFH-DA for 30 min at 37 °C. The fluorescence intensity of DCF was subsequently measured at an excitation wavelength of 488 nm and an emission wavelength of 525 nm using a confocal laser scanning microscope (magnification: × 200; Olympus Corporation). Mean fluorescence intensity (MFI) was calculated from six randomly selected fields and analyzed using ImageJ 1.41 software.

2.10. Determination of malondialdehyde

Following 24 h of drug treatment, HUVECs were harvested and rinsed with ice-cold phosphate-buffered saline. The cells were then lysed by incubation with lysis buffer on ice for 30 min. After incubation, the cell lysates were centrifuged at 10,000×g for 10 min at 4 °C, and the supernatants were carefully collected. Protein concentrations were determined using a BCA protein assay kit according to the manufacturer's instructions, with a standard curve generated via a five-point calibration method. Finally, MDA levels were calculated using commercial assay kits from Beyotime Biotechnology, following the provided protocols.

2.11. Immunofluorescence staining

The HUVECs cultured on glass coverslips were fixed with 4% paraformaldehyde for 15 min, permeabilized with 0.1% Triton X-100 for 10 min and blocked with 5% bovine serum albumin (BSA) for 1 h at room temperature. The cells were subsequently incubated overnight at 4 °C with primary antibodies targeting Nrf2 (1:400) and GPX4 (1:400), followed by incubation with Alexa Fluor 488- or Alexa Fluor 594-conjugated secondary antibodies (1:500) for 1 h in the dark. Nuclear counterstaining was performed using DAPI (1 μg/mL) for 5 min. Fluorescence images were acquired under consistent exposure conditions using a fluorescence microscope, and mean fluorescence intensity was quantitatively analyzed using ImageJ software based on at least three randomly selected fields per experimental group.

2.12. Western blot analysis

After the indicated treatment, the cells were lysed using a RIPA lysis buffer and then centrifuged at 14,000 rpm for 15 min at 4 °C. The supernatants were quantified using a BCA Protein Quantitation Assay. Subsequently, samples were boiled at 100 °C for 5 min. Equal amounts of protein samples were separated by SDS-PAGE and transferred onto PVDF membranes (Millipore, USA). After being blocked with 5% nonfat milk, the membranes were incubated overnight at 4 °C with primary antibodies. The antibodies used included: Bcl-2 (1:1000), Bax (1:1000), Caspase-3 (1:1000), Nrf2 (1:1000), GPX4 (1:1000), and GAPDH (1:5000). Following incubation with primary antibodies, the membranes were washed and then incubated with a horseradish peroxidase-conjugated secondary antibody for 1 h at room temperature. Immunoreactive protein bands were visualized using the Bio-Rad Gel Doc™2000 imaging system (Bio-Rad Laboratories, USA) through ECL luminescence solution and quantitatively analyzed using Image J 1.41 software.

2.13. Statistical analysis

Statistical analyses were conducted using SPSS 18.0 software. Differences among multiple groups were evaluated through one-way analysis of variance (ANOVA) followed by Dunnett's test or non-parametric Kruskal-Wallis analysis followed by Dunn's test. The data are presented as mean ± standard deviation (SD), and a significance level of p < 0.05 was considered statistically significant.

3. Results

3.1. PSP treatment ameliorates diabetes-induced vascular endothelial injury and regulates lipid metabolism

To investigate the effect of PSP on vascular endothelial pathology and lipid metabolism in diabetic rats, histopathological analysis of the abdominal aorta was performed using HE staining, and serum lipid profiles were obtained by related assay kits. As shown in Fig. 1a, the control group exhibited intact, well-organized endothelial cells with minimal intercellular space, whereas the diabetic group displayed marked endothelial cell swelling and increased interstitial separation. Notably, these pathological alterations were substantially attenuated following PSP treatment. Furthermore, body weight and fasting blood glucose levels in diabetic rats were evaluated following 8 weeks of treatment with PSP. The results demonstrated that high-dose PSP reduced both body weight and fasting blood glucose levels in diabetic rats (Fig. 1b and c). Lipid profile assessments revealed that, compared with the control group, the diabetic group exhibited markedly elevated levels of TG and LDL, both of which were effectively lowered following PSP administration. In contrast, HDL levels were reduced in the diabetic group but were partially restored following PSP treatment (Fig. 1d, e, and 1f). These findings indicate that PSP not only ameliorates diabetes-associated vascular endothelial injury but also exerts favorable regulatory effects on lipid metabolism.

Fig. 1.

Fig. 1

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Hematoxylin and eosin staining and blood lipid assessment. (a) Hematoxylin and eosin staining. (b) Analysis of body weight in rats following 8 weeks of oral gavage with PSP (n = 6). (c) Analysis of fasting blood glucose levels in rats after 8 weeks of oral administration of PSP. (d) Triglyceride content in serum (n = 6). (e) Levels of low-density lipoprotein in serum (n = 6). (f) High-density lipoprotein content in serum (n = 6). #p < 0.05 vs. Control group; *p < 0.05, **p < 0.01 vs. STZ group.

3.2. Proteomic analysis indicates the ameliorative effects of PSP on diabetes-induced vascular injury

Next, to investigate the potential mechanism underlying the effects of PSP on vascular endothelial cells in diabetic rats, a proteomics analysis was conducted. As shown in Fig. 2a, a total of 305 differentially expressed proteins were identified, including 249 downregulated and 56 upregulated proteins (Shown in Supplementary Material 1). Using stringent analytical parameters - including a correlation coefficient of 0.96, a soft threshold power of 12, and a minimum module size of 30—four co-expression modules (ME greenyellow, ME green, ME salmon, and ME magenta) were identified as being significantly associated with the therapeutic effects of PSP (Fig. 2b–c). These modules collectively comprised 702 proteins (Supplementary Material 2). Moreover, as illustrated in Fig. 2d and 268 overlapping proteins were identified between the differentially expressed proteins and those within the PSP-associated modules.

Fig. 2.

Fig. 2

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Proteomic analysis indicates the ameliorative effects of PSP on diabetes-induced vascular injury. (a) Volcano plot of model group and PSP treatment group (n = 3). (b) Scale independence and mean connectivity plot. (c) Analysis module and heatmap of correlations between scores. (d) Venn plot of differential proteins and WGCNA. (e) GO analysis. (f) KEGG analysis.

Enrichment analysis revealed that the intersecting proteins are predominantly localized to 167 cellular components, including the mitochondrial inner membrane, membrane region, peroxisome, inner mitochondrial membrane protein complex, phagocytic vesicle, oxidoreductase complex, peroxisomal membrane, chylomicron. These proteins serve as guanyl ribonucleotide binding and GTP binding agents and exhibit protein heterodimerization activity. They also possess oxidoreductase activity involved in acting on CH–OH group of donors and antioxidant activity. Additionally, they demonstrate oxidoreductase activity involved in acting on the aldehyde or oxo group of donors and fatty acid binding among other molecular functions (143 in total). The proteins are actively engaged in various biological processes such as fatty acid metabolic process, organic acid catabolic process, oxidative phosphorylation, positive regulation of cysteine-type endopeptidase activity involved in apoptotic process and apoptotic signaling pathway. Furthermore, they participate in lipid oxidation and mitochondrial ATP synthesis coupled electron transport along with numerous other biological processes (1034 in total) depicted by Fig. 2e and Supplementary Material 3. Moreover, KEGG pathway analysis highlights their association with Glycolysis/Gluconeogenesis, Pyruvate metabolism, Fatty acid degradation, Fatty acid metabolism, Citrate cycle (TCA cycle), Oxidative phosphorylation, TGF-beta signaling pathway, PI3K-AKT signaling pathway, Peroxisome, PPAR signaling pathway, and Cholesterol metabolism et al. (Fig. 2f and Supplementary Material 4). Collectively these findings suggest that PSP protects against diabetes-induced endothelial cell injury by interfering with oxidative stress injury.

3.3. PSP treatment inhibits PA-induced apoptosis of HUVECs

In our proteomic analysis, apoptosis plays a pivotal role in the mechanism by which PSP mitigates diabetes-induced vascular endothelial damage. Initially, we determined the concentrations of PA and PSP (Fig. 3a–b) and evaluated the effect of PSP on the viability of HUVECs under PA stimulation. The results demonstrated that, compared with the PA-treated group, PSP significantly enhanced cell viability (Fig. 3c). Concurrently, PA stimulation led to mitochondrial membrane potential depolarization relative to the control group; however, PSP treatment effectively reversed this disruption in MMP in HUVECs (Fig. 3d–e). Moreover, PSP treatment markedly reduced the protein expression levels of Caspase-3 (Fig. 3f) and Bax (Fig. 3g), while significantly upregulating Bcl-2 protein expression (Fig. 3h). These results collectively indicate that PSP suppresses PA-induced apoptosis in HUVECs.

Fig. 3.

Fig. 3

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PSP inhibits PA-induced apoptosis in HUVECs. (a) The viability of HUVECs following treatment with varying concentrations of PA for 12 and 24 h (n = 6). (b) PSP concentration screening (n = 6). (c) Cell viability assay of PSP interfering with PA-induced HUVECs (n = 6). (d, e) Measurement of mitochondrial membrane potential (scale bar = 75 μm, (n = 6)). (f-i) Western blot analysis of apoptotic protein expression in HUVECs (n = 3). #p < 0.05 vs. Control group; *p < 0.05, **p < 0.01 vs. PA group.

3.4. PSP alleviates oxidative stress damage and enhances GPX4 and Nrf2 levels in PA-induced HUVECs

To investigate whether PSP protects vascular endothelial cells against PA-induced oxidative injury, intracellular ROS and MDA levels were assessed. As shown in Fig. 4a–c, treatment with PA significantly increased ROS fluorescence intensity and MDA content compared to the control group, indicating the induction of oxidative stress. In contrast, PSP treatment markedly reduced both ROS and MDA levels in a dose-dependent manner, with the most pronounced effect observed at 500 mg/L. Western blot analysis further revealed that PA significantly downregulated the protein expression of Nrf2 and GPX4 relative to the control group, whereas PSP treatment effectively restored their expression in a concentration-dependent manner (Fig. 4d–f). Consistent with these findings, immunofluorescence staining demonstrated that PA exposure reduced the fluorescence intensity of Nrf2 and GPX4, while PSP treatment significantly enhanced the fluorescence signal of both proteins in a dose-dependent manner (Fig. 4–j). Collectively, these results suggest that PSP alleviates PA-induced oxidative stress in HUVECs, by activating the Nrf2/GPX4 signaling pathway and restoring cellular redox homeostasis.

Fig. 4.

Fig. 4

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PSP alleviates oxidative stress and enhances GPX4 and Nrf2 expression in PA-induced HUVECs. (a, b) ROS fluorescence expression level (scale bar: 1:100 μm, (n = 6)). (c) Expression levels of MDA (n = 6). (d-f) Western blotting to evaluate the expression levels of GPX4 and Nrf2 in HUVECs (n = 3). (g, h) Immunofluorescence staining of GPX4 (red) and Nrf2 (green) in HUVECs under different treatments; nuclei were counterstained with DAPI (blue). (i, j) Quantitative analysis of the relative fluorescence intensity of Nrf2 and GPX4 (n = 3). #p < 0.05, ##p < 0.01 vs. control group; *p < 0.05, **p < 0.01 vs. PA group.

4. Discussion

Vascular endothelial injury is a key initiating factor for the development of diabetes and its vascular complications [22]. Under hyperglycemic conditions, excess reactive oxygen species generation disrupts endothelial cell function, impairs nitric oxide bioavailability [23,24], and induces vasoconstriction and endothelial barrier disruption. This oxidative stress further drives the accelerated accumulation of advanced glycation end products, exacerbating vascular endothelial damage [25]. Currently, effective interventions targeting these mechanisms remain limited. The traditional Chinese medicine PS is employed for managing diabetes and its complications owing to its therapeutic properties [26,27].The primary bioactive constituent of PSP demonstrates a range of pharmacologically significant activities, including antioxidant effects [28], immunomodulation [29], lipid-lowering action [27], and cytokine inhibition [30]. Through integrated proteomic profiling and experimental validation, the current investigation demonstrates that PSP significantly ameliorates diabetic vascular endothelial injury, identifying it as a promising therapeutic agent for this condition.

Proteomics provides a robust platform for elucidating disease mechanisms through large-scale protein profiling under pathological conditions [[31], [32], [33]]. By applying proteomic analysis to vascular tissues, this study identified several molecular pathways underlying PSP-mediated protective effects, particularly those associated with lipid metabolism, apoptosis, and oxidative stress regulation. These findings align with previous studies demonstrating that PSP enhances glycerophospholipid metabolism and improves lipid homeostasis in hyperlipidemic models [34,35]. Notably, our results show that PSP significantly reduced serum triglyceride and low-density lipoprotein levels while increasing high-density lipoprotein levels in diabetic rats. This suggests that the vascular protective effects of PSP are, at least in part, attributable to its capacity to restore lipid metabolic balance and mitigate diabetes-associated dyslipidemia, a key factor in the development of endothelial dysfunction.

Endothelial apoptosis is a major event contributing to vascular dysfunction in diabetes, largely due to the imbalance of Bcl-2 family proteins that regulate mitochondrial integrity [[36], [37], [38]]. These findings are complementary to previous reports showing that PSP attenuates apoptosis via PI3K/AKT/mTOR-mediated mitochondrial protection [39]. Similarly, our study found that PSP treatment significantly enhanced cell viability in HUVECs, inhibited apoptosis-related protein levels of Caspase-3 and Bax, and increased Bcl-2 expression. Additionally, the reduction of mitochondrial membrane potential is a hallmark event in the early stages of apoptosis [40]. Fluorescence analysis of mitochondrial membrane potential revealed that PSP restored mitochondrial membrane potential in PA-induced HUVECs. Critically, Oxidative stress plays a central role in diabetic endothelial damage [[41], [42], [43], [44], [45], [46]]. Central to cellular defense against oxidative damage is the transcription factor Nrf2, whose coordinated signaling pathway constitutes a fundamental protective mechanism against ROS and xenobiotic insults [47]. Our study found that PSP treatment significantly reduced the ROS level and oxidative stress product MDA content in PA-induced vascular endothelial cells, and up-regulated the expression levels of the key transcription factor Nrf2 and its downstream protein GPX4. These findings indicate that PSP can inhibit oxidative stress to protect vascular endothelial cells.

Although the present study demonstrated that eight weeks of PSP treatment effectively alleviated diabetes-induced endothelial injury and metabolic disturbance, it mainly reflects short-to mid-term effects. The long-term efficacy, safety, and durability of PSP's vascular protection remain determined. Moreover, due to its high molecular weight and limited oral bioavailability, the pharmacokinetic profile and systemic availability of PSP are not yet fully understood. It is also possible that PSP exerts its effects indirectly through modulation of gut microbiota and their metabolites rather than direct absorption. Therefore, future studies should focus on evaluating the chronic outcomes, safety, and optimal dosage of PSP, as well as clarifying its absorption, metabolic transformation, and delivery mechanisms to support its potential clinical application.

In parallel, the study establishes that PSP ameliorates diabetes-induced vascular endothelial injury through lipid metabolic reprogramming. Complementarily, PSP counteracts PA-induced endothelial pathophysiology via (1) Direct modulation of apoptosis regulators, (2) Mitochondrial membrane potential stabilization and viability restoration, (3) ROS/lipid peroxide scavenging partly through Nrf2-GPX4 activation. This coordinated mitigation of metabolic dysfunction, apoptotic cascades, and oxidative stress (Fig. 5), demonstrates PSP's multi-target therapeutic efficacy against diabetic vasculopathy, positioning it as a promising translational candidate for diabetes management.

Fig. 5.

Fig. 5

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Graphical Abstract: Polygonatum sibiricum polysaccharides ameliorate diabetes-induced vascular endothelial injury partly through Nrf2/GPX4 activation.

CRediT authorship contribution statement

Dongdong Wu: Formal analysis, Validation. Jing Zhao: Conceptualization, Writing – original draft, Writing – review & editing. Qifan Yang: Validation. Rourou Fang: Validation. Shouzhu Xu: Conceptualization.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by several funding sources, including the National Natural Science Foundation of China (No. 82100488, No. 82105016), Key Research and Development Program Project of Shaanxi Province (No. 2024SF-YBXM-471), Scientific Research Fund Project of Shaanxi Province Department of Education (No. 21JS012), Qin Chuangyuan “scientist + engineer” team construction of Shaanxi Province (No. 2022KXJ-164) and the Innovation Capability Support Program of Xianyang (No. L2024-CXNL-KJRCTD-KJRC-0015).

Footnotes

Appendix A

Supplementary data to this article can be found online at https://doi.org/10.1016/j.bbrep.2026.102570.

Appendix A. Supplementary data

The following are the Supplementary data to this article:

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mmc2.xlsx (20.6KB, xlsx)
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mmc3.xlsx (142.8KB, xlsx)
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mmc4.xlsx (37.7KB, xlsx)

Data availability

The proteomics data generated in this study have been deposited at the iProX repository (https://www.iprox.cn/) with accession number IPX0016266000 and are accessible via the ProteomeXchange Consortium with identifier PXD075930.

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Multimedia component 1
mmc1.xlsx (28.8KB, xlsx)
Multimedia component 2
mmc2.xlsx (20.6KB, xlsx)
Multimedia component 3
mmc3.xlsx (142.8KB, xlsx)
Multimedia component 4
mmc4.xlsx (37.7KB, xlsx)

Data Availability Statement

The proteomics data generated in this study have been deposited at the iProX repository (https://www.iprox.cn/) with accession number IPX0016266000 and are accessible via the ProteomeXchange Consortium with identifier PXD075930.

Articles from Biochemistry and Biophysics Reports are provided here courtesy of Elsevier

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