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. 2024 May 10;16(12):1255–1266. doi: 10.1080/17568919.2024.2342700

Synthesis, anti-diabetic profiling and molecular docking studies of 2-(2-arylidenehydrazinyl)thiazol-4(5H)-ones 

Hasnain Mehmood a, Muhammad Haroon b,**, Tashfeen Akhtar a,*, Simon Woodward c, Saadia Haq d,e, Saad M Alshehri f
PMCID: PMC11244696  PMID: 38989987

Abstract

Aim: To synthesize novel more potent anti-diabetic agents. Methodology: A simple cost effective Hantzsch's synthetic strategy was used to synthesize 2-(2-arylidenehydrazinyl)thiazol-4(5H)-ones. Results: Fifteen new 2-(2-arylidenehydrazinyl)thiazol-4(5H)-ones were established to check their anti-diabetic potential. From alpha(α)-amylase inhibition, anti-glycation and anti-oxidant activities it is revealed that most of the compounds possess good anti-diabetic potential. All tested compounds were found to be more potent anti-diabetic agents via anti-glycation mode. The results of α-amylase and anti-oxidant inhibition revealed that compounds are less active against α-amylase and anti-oxidant assays. Conclusion: This study concludes that introduction of various electron withdrawing groups at the aryl ring and substitution of different functionalities around thiazolone nucleus could help to find out better anti-diabetic drug.

Keywords: : anti-diabetic, cyto-toxicity, HRMS, molecular docking, NMR, SAR, thiazol-4(5H)-ones

Plain language summary

Diabetes is a most spreading chronicle disease effecting millions of peoples across the globe every year and this number increases day by day. To cure the human population from this dilemma, we had synthesized, characterized and evaluated the anti-diabetic behavior of our synthesized compounds. α-Amylase, in vitro anti-glycation and anti-oxidant assays were performed to find out good lead for Diabetes Mellitus. All tested compounds were found to be excellent anti-glycating agents with IC50 values far better than standard amino-guanidine (IC50 = 3.582 ± 0.002 μM). Compound 4m was most efficient glycation inhibitor (IC50 = 1.095 ± 0.002 μM). Cytotoxicity of all compounds was determined with in vitro hemolytic assay and found all compounds safe and bio-compatible to humans at all tested concentrations. The inhibition potential was also examined with theoretical docking studies to support our experimental results against human pancreatic alpha-amylase (HPA) and human serum albumin (HSA) proteins. All compounds showed excellent binding affinity with HSA active pockets however, only compound 4h and 4k binding affinity was good with HPA.

Plain language summary

Summary points.

  • Thiazol-4-ones are the most effective heterocyclic compounds among other azoles due to large number of biological applications. A large number of commercially available pharmaceutical drugs contain this nucleus.

  • In current study, a simple two-step synthetic protocol was adopted to synthesize 2-(2-arylidenehydrazinyl)thiazol-4(5H)-ones. The proposed structures were analyzed and confirmed with routine spectroscopic techniques.

  • Functional groups were justified with FTIR spectroscopic data. Total number of proton and carbons present within the proposed structures were justified with NMR spectroscopic data and confirmation of proposed analogs was ascertain with HRMS.

  • The synthesized analogs were tested for their anti-diabetic potential. Following biological assays were used to determine the anti-diabetic potential of synthesized compounds; α-amylase, anti-glycation and anti-oxidant.

  • From α-amylase assay we concluded that none of the tested compounds is a better α-amylase inhibitor.

  • All tested compounds showed excellent anti-glycation potential.

  • Free radical scavenging assay revealed only compound 4h to be an excellent anti-oxidant agent.

  • In vitro hemolytic assay determined almost all compounds are safe to use and found them bio-compatible.

  • Molecular docking study was used to find out the ligand and receptor interactions with AutoDock vina software.

  • From study, it is hypothesized that attachment of electron withdrawing groups and further substitution at the arylidene and thiazole-4-one rings could help to find out the best anti-diabetic scaffold.

1. Introduction

Thiazol-4(5H)-one is a class of heterocyclic organic compounds containing an internal amido function within the thiazole ring (see Figure 1 for representative examples). This class has attracted significant attention of the researchers due to its easy derivatization and medicinal chemistry significance [1–3]. Thiazol-4(5H)-ones have been widely studied for their diverse pharmacological properties, as they exhibit a wide range of biological activities including; anti-microbial [4,5], anti-viral and anti-cancer [6,7] properties. The tyrosinase [8] and clathrin [9] inhibition; together with anti-inflammatory [10] and anti-histaminic [11] behavior making them interesting leads for onward drug development. Some representative thiazol-4(5H)-one derivatives with known biological activity are presented in Figure 1.

Figure 1.

Figure 1.

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Recent representative thiazol-4(5H)-one based biologically active molecules.

Recently, a large number of reports detailing thiazol-4(5H)-one derivatives as potential therapeutic agents for diabetes mellitus have appeared [12–15]. This chronic metabolic disorder, characterized by persistent hyperglycemia represents a significant and developing clinical need across the globe [16–19]. Thiazol-4(5H)ones possess significant anti-diabetic activity, mainly attributed to their ability to activate peroxisome proliferator-activated receptor gamma (PPAR-γ) [20]. The PPAR-γ protein plays a critical role in glucose homeostasis, insulin sensitivity and lipid metabolism. Activation of PPAR-γ promotes glucose uptake by increasing the expression of glucose transporters in the skeletal muscles and adipose tissues, resulting in improved insulin sensitivity [20]. Pioglitazone, rosiglitazone and other thiazol-4(5H)-ones have been approved by the US FDA for the treatment of Type 2 diabetes mellitus, and reduce insulin resistance and triglyceride levels in patients with Type 2 diabetes (Figure 2).

Figure 2.

Figure 2.

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Thiazol-4(5H)-ones based US FDA approved anti-diabetic drugs.

The synthesis and modification around thiazol-4(5H)-one ring remains an active area of research, and the development of new thiazolone-based drugs is likely to have a significant impact on the treatment of diabetes. Therefore, further research is needed to explore full potential of thiazolones in the treatment of diabetes mellitus. An important thiazolone derivative with potential anti-diabetic property, presented in Figure 3, prompted the design of current project.

Figure 3.

Figure 3.

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Synthetic modulation to our current research.

Protein glycation, higher blood glucose level by enzyme action and oxidation are most damaging processes linked with diabetes. The inhibition of these processes is a solution to diabetic complications [21]. Therefore, as part of our on-going research in pursuance of new active anti-diabetic compounds [21], we synthesized the arylidene hydrazinylthiazolone based scaffolds (Figure 3) and studied their anti-diabetic properties. The experimental findings were also supported with molecular docking studies of these scaffolds with human pancreatic alpha-amylase (HPA) and human serum albumin (HSA) proteins.

2. Experimental

2.1. Materials & methods

Analytical grade reagents and solvents were used in the synthesis, all sourced from well-reputed suppliers (Merck-Sigma-Aldrich [MA, USA], Fischer [MA, USA] and Across Organics [Antwerp, Belgium]). The progress of the reaction and purity of the compounds were identified/monitored by TLC using pre-coated aluminum sheets (Kieselgel 60, F254, E. Merck, Germany). Melting points were recorded by open capillary method using DMP-300 A&E Lab (London, UK) apparatus and are uncorrected. A Shimadzu Ultraviolet-1800 spectrophotometer (MD, USA) was used to record the UV-vis absorption spectra. IR spectra were recorded on Bruker Opus using the ATR mode. 1H- and 13C-NMR spectra were recorded on Bruker DPX 400 and 500 spectrometers using DMSO-d6. High-resolution mass spectra (HRMS) were recorded using Bruker micro time of flight (TOF) or vacuum generators (VG) Micromass AutoSpec spectrometers using electrospray ionization (ESI), electron impact (EI) or field desorption (FD) ionization modes. The biological assays conducted to evaluate the diabetic studies were performed by the methods followed in our previous studies [21,22].

2.2. Syntheses of 2-(2-arylidenehydrazinyl)thiazol-4(5H)-ones (4a–o)

The syntheses and modification of thiazol-4(5H)-one derivatives have been widely studied and variety of synthetic strategies have been developed so far to obtain this important class of compounds [8,23,24]. An important method of synthesis involves the use of α-halocarbonyl compounds and thioamides as starting material. In our current synthetic pathway, substituted thiosemicarbazones [25–27] (0.001 mol), ethyl bromoacetate (0.001 mol) and sodium acetate (2.0 equivalent) in methanol solvent were heated under reflux for 3 h. Reaction progress was monitored by TLC and upon completion; the reaction was quenched with crushed ice. Precipitates formed, filtered and washed with copious deionized water to afford TLC pure product. Solid was dried and used for further studies without any additional purification. The NMR spectra were recorded in DMSO-d6 solvent.

2.3. 2-(2-(1-(o-Tolyl)ethylidene)hydrazinyl)thiazol-4(5H)-one (4a)

White solid; Yield: 70%; Melting point: 146–148°C; Rf: 0.46 (acetone/n-hexane, 1:3); λmax: 334 nm; FTIR (ATR) cm-1: 3078 (N-H stretching), 2976 (C-H aliphatic stretching), 1707 (C=O stretching), 1614 (C=N stretching), 1435 (C-H aliphatic bending), 709 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 11.93 (s, 1H, H-N-), 7.64 (d, 2H, Ar-H, J = 7.3 Hz), 7.32 (t, 1H, Ar-H, J = 8.0 Hz), 7.25 (t, 1H, Ar-H, J = 7.3 Hz), 3.86 (s, 2H, -CH2-), 2.36 (s, 6H, Ar-CH3, H3C-C=N-); 13C-NMR (100 MHz): δ (ppm) 174.4 (C=O), 160.8 (thiazol-4(5H)-one ring C2), 138.3 (-C=N-), 137.9 (Ar-C-CH3), 130.9, 128.8, 127.4, 125.5, 124.1 (Ar-C), 33.2 (-CH2-), 21.6 (Ar-CH3), 15.2 (H3C-C=N-); HRMS: Calcd for C12H14N3OS [M+H]+: 248.0857; found: 248.0852. Calcd for C12H13N3NaOS [M+Na]+: 270.0677; found: 270.0674. C24H26N6NaO2S2 [2M+Na]+: 517.1457; found: 517.1447.

2.4. 2-(2-(1-(4-Chlorophenyl)ethylidene)hydrazinyl)thiazol-4(5H)-one (4b)

Beige solid; Yield: 69%; Melting point: 208–209°C; Rf: 0.42 (acetone/n-hexane, 1:3); λmax: 305 nm; FTIR (ATR) cm-1: 3053 (N-H stretching), 2987 (C-H aliphatic stretching), 1712 (C=O stretching), 1593, 1568 (C=C aromatic ring stretching), 1489 (C-H aliphatic bending), 704 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 11.90 (s, 1H, H-N-), 7.85 (d, 2H, Ar-H, J = 8.8 Hz), 7.50 (d, 2H, Ar-H, J = 8.8 Hz), 3.87 (s, 2H, -CH2-), 2.36 (s, 3H, -CH3); 13C-NMR (100 MHz): δ (ppm) 174.4 (C=O), 165.2 (thiazol-4(5H)-one ring C2), 137.0 (C=N-), 134.9, 128.9, 128.6 (Ar-C), 33.3 (-CH2-), 14.9 (-CH3); HRMS: Calcd for C11H11ClN3OS [M+H]+: 268.0311; found: 268.0306. Calcd for C11H10ClN3NaOS [M+Na]+: 290.0131; found: 290.0120.

2.5. 2-(2-(2-Ethoxybenzylidene)hydrazinyl)thiazol-4(5H)-one (4c)

Beige solid; Yield: 77%; Melting point: 242–244°C; Rf: 0.52 (acetone/n-hexane, 1:3); λmax: 311 nm; FTIR (ATR) cm-1: 2970 (C-H aliphatic stretching), 1714 (C=O stretching), 1625 (C=N stretching), 1566, 1489, 1396 (C=C aromatic ring stretching), 1448 (C-H aliphatic bending), 1043 (C-O stretching), 746 (C-S stretching); 1H-NMR (500 MHz): δ (ppm) 11.95 (s, 1H, H-N-), 8.63 (s, 1H, H-C=N-), 7.83 (d, 1H, Ar-H, J = 6.0 Hz), 7.43 (t, 1H, Ar-H, J = 7.5 Hz), 7.09 (d, 1H, Ar-H, J = 8.5 Hz), 7.01 (t, 1H, Ar-H, J = 7.5 Hz), 4.11 (q, 2H, -O-CH2-CH3, J = 7.1 Hz), 3.90 (s, 2H, -CH2-), 1.37 (t, 3H, CH3-CH2-, J = 7.1 Hz); 13C-NMR (125 MHz): δ (ppm) 174.8 (C=O), 157.9 (thiazol-4(5H)-one ring C2 and Ar-C-OC2H5 signal overlap), 151.9 (H-C=N-), 132.7, 126.6, 122.5, 121.1, 113.3 (Ar-C), 64.3 (-O-CH2-CH3), 33.5 (-CH2-), 15.1 (CH3-CH2-); HRMS: Calcd for C12H14N3O2S [M+H]+: 264.0806; found: 264.0799. Calcd for C12H13N3NaO2S [M+Na]+: 286.0626; found: 286.0616. C24H26N6NaO4S2 [2M+Na]+: 549.1354; found: 549.1341.

2.6. 2-(2-(2-(Trifluoromethyl)benzylidene)hydrazinyl)thiazol-4(5H)-one (4d)

Off-white solid; Yield: 66%; Melting point: 236–238°C; Rf: 0.58 (acetone/n-hexane, 1:3); λmax: 302 nm; FTIR (ATR) cm-1: 2937 (C-H aliphatic stretching), 1730 (C=O stretching), 1631 (C=N stretching), 1583, 1489 (C=C aromatic ring stretching), 1425 (C-H aliphatic bending), 736 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 12.12 (s, 1H, H-N-), 8.58 (s, 1H, H-C=N-), 8.18 (d, 1H, Ar-H, J = 7.8 Hz), 7.85–7.77 (m, 2H, Ar-H), 7.68 (t, 1H, Ar-H, J = 7.8 Hz), 3.94 (s, 2H, -CH2-); 19F-NMR (375 MHz): δ (ppm) -56.66; 13C-NMR (100 MHz): δ (ppm) 174.8 (C=O), 168.4 (thiazol-4(5H)-one ring C2), 151.7 (H-C=N-), 133.4, 132.2, 131.2, 128.0, 127.7, 127.4, 127.1, 126.6 (q, 4JC-F = 3.9 Hz), 125.9, 123.2 (Ar-C), 33.7 (-CH2-); HRMS: Calcd for C11H9F3N3OS [M+H]+: 288.0418; found: 288.0409. Calcd for C11H8F3N3NaOS [M+Na]+: 310.0238; found: 310.0235. C22H16F6N6NaO2S2 [2M+Na]+: 597.0578; found: 597.0571.

2.7. 2-(2-(3-(Trifluoromethyl)benzylidene)hydrazinyl)thiazol-4(5H)-one (4e)

Tea pink solid; Yield: 77%; Melting point: 248–249°C; Rf: 0.42 (acetone/n-hexane, 1:3); λmax: 310 nm; FTIR (ATR) cm-1: 2939 (C-H aliphatic stretching), 1722 (C=O stretching), 1627 (C=N stretching), 1429 (C-H aliphatic bending), 1381, 1321 (C=C aromatic ring stretching), 713 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 12.06 (s, 1H, H-N-), 8.53 (s, 1H, H-C=N-), 8.07 (d, 2H, Ar-H, J = 8.0 Hz), 7.81 (d, 1H, Ar-H, J = 8.0 Hz), 7.71 (t, 1H, Ar-H, J = 7.8 Hz), 3.92 (s, 2H, -CH2-); 19F-NMR (375 MHz): δ (ppm) -61.39; 13C-NMR (100 MHz): δ (ppm) 174.6 (C=O), 167.1 (thiazol-4(5H)-one ring C2), 155.3 (H-C=N-), 135.8, 131.5, 130.5, 129.9, 127.3, 125.8 (Ar-C), 124.5 (q, -CF3, J = 242.0 Hz), 33.5 (-CH2-); HRMS: Calcd for C11H9F3N3OS [M+H]+: 288.0418; found: 288.0409. Calcd for C11H8F3N3NaOS [M+Na]+: 310.0238; found: 310.0227. C22H16F6N6NaO2S2 [2M+Na]+: 597.0578; found: 597.0563.

2.8. 2-(2-(4-(Trifluoromethyl)benzylidene)hydrazinyl)thiazol-4(5H)-one (4f)

Beige solid; Yield: 69%; Melting point: 208–209°C; Rf: 0.42 (acetone/n-hexane, 1:3); λmax: 320 nm; FTIR (ATR) cm-1: 3053 (N-H stretching), 2939 (C-H aliphatic stretching), 1707 (C=O stretching), 1639 (C=N stretching), 1411 (C-H aliphatic bending), 736 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 12.08 (s, 1H, H-N-), 8.51 (s, 1H, H-C=N-), 7.97 (d, 2H, Ar-H, J = 8.4 Hz), 7.83 (d, 2H, Ar-H, J = 8.4 Hz), 3.93 (s, 2H, -CH2-); 13C-NMR (100 MHz): δ (ppm) 174.7 (C=O), 155.3 (thiazol-4(5H)-one ring C2), 138.6 (H-C=N-), 130.8, 130.5, 128.6 (Ar-C), 126.2 (q, 4JC-F = 3.9 Hz), 123.2 (Ar-C), 33.6 (-CH2-); HRMS: Calcd for C11H9F3N3OS [M+H]+: 288.0418; found: 288.0412. Calcd for C11H8F3N3NaOS [M+Na]+: 310.0238; found: 310.0228. C22H16F6N6NaO2S2 [2M+Na]+: 597.0578; found: 597.0556.

2.9. 2-(2-(5-Chloro-2-hydroxybenzylidene)hydrazinyl)thiazol-4(5H)-one (4g)

White solid; Yield: 81%; Melting point: 295–297°C; Rf: 0.26 (acetone/n-hexane, 1:3); λmax: 323 nm; FTIR (ATR) cm-1: 3039 (N-H stretching), 2964 (C-H aliphatic stretching), 1708 (C=O stretching), 1560, 1475, 1408, 1330 (C=C aromatic ring stretching), 1091 (C-O stretching), 744 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 12.13 (s, 1H, -N-H), 10.93 (s, 1H, -OH), 8.61 (s, 1H, H-C=N-), 7.67 (d, 1H, Ar-H, J = 2.8 Hz), 7.36 (dd, 1H, Ar-H, J = 8.8, 2.8 Hz), 6.98 (d, 1H, Ar-H, J = 8.8 Hz), 3.98 (s, 2H, -CH2-,); 13C-NMR (100 MHz): δ (ppm) 174.4 (C=O), 165.9 (thiazol-4(5H)-one ring C2), 157.1 (Ar-C-OH), 156.0 (H-C=N-), 132.0, 130.8, 129.2, 123.5, 120.7, 118.7 (Ar-C), 33.8 (-CH2-); HRMS: Calcd for C10H9ClN3O2S [M+H]+: 270.0104; found: 270.0099. Calcd for C10H8ClN3NaO2S [M+Na]+: 291.9924; found: 291.9918. C20H16Cl2N6NaO4S2 [2M+Na]+: 560.9950; found: 560.9941.

2.10. 2-(2-(2-Hydroxy-5-nitrobenzylidene)hydrazinyl)thiazol-4(5H)-one (4h)

Yellow solid; Yield: 80%; Melting point: 282–284°C; Rf: 0.24 (acetone/n-hexane, 1:3); λmax: 355 nm; FTIR (ATR) cm-1:) 2941 (C-H aliphatic stretching), 1712 (C=O stretching), 1627 (C=N stretching), 1595, 1568, 1519, 1483 (C=C aromatic ring stretching), 1400 (C-H aliphatic bending), 1101 (C-O stretching), 717 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 12.09 (s, 1H, H-N-), 8.72 (s, 1H, H-C=N-), 8.59 (d, 1H, Ar-H, J = 2.9 Hz), 8.20 (dd, 2H, Ar-H, J = 9.0, 2.9 Hz), 7.13 (d, 1H, Ar-H, J = 9.0 Hz), 3.98 (s, 2H, -CH2-); 13C-NMR (100 MHz): δ (ppm) 174.4 (C=O), 163.5 (Ar-C-OH), 154.8 (thiazol-4(5H)-one ring C2), 140.4 (H-C=N-), 127.7, 125.6, 119.9, 117.7 (Ar-C), 33.9 (-CH2-); HRMS: Calcd for C10H9N4O4S [M+H]+: 281.0344; found: 281.0333. Calcd for C10H8N4NaO4S [M+Na]+: 303.0164; found: 303.0153. C20H16N8NaO8S2 [2M+Na]+: 583.0430; found: 583.0407.

2.11. 2-(2-(5-Fluoro-2-methoxybenzylidene)hydrazinyl)thiazol-4(5H)-one (4i)

White solid; Yield: 72%; Melting point: 268–270°C; Rf: 0.37 (acetone/n-hexane, 1:3); λmax: 321 nm; FTIR (ATR) cm-1: 3321 (N-H stretching), 2937 (C-H aliphatic stretching), 1714 (C=O stretching), 1639 (C=N stretching), 1575, 1489, 1454 (C=C aromatic ring stretching), 1431 (C-H aliphatic bending), 1035 (C-O stretching), 727 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 12.04 (s, 1H, H-N-), 8.53 (s, 1H, H-C=N-), 7.68 (d, 1H, Ar-H, J = 7.9 Hz), 7.39 (t, 1H, Ar-H, J = 7.9 Hz), 7.22–7.16 (m, 1H, Ar-H), 3.92 (s, 2H, -CH2-), 3.91 (s, 3H, -CH3); 19F-NMR (375 MHz): δ (ppm) -130.74; 13C-NMR (100 MHz): δ (ppm) 174.8 (C=O), 156.9 (thiazol-4(5H)-one ring C2), 154.4 (Ar-C-OCH3), 150.8 (H-C=N-), 146.9 (d, 3JC-F = 11.7 Hz, Ar-C-F), 129.1 (d, 4JC-F = 2.6 Hz, Ar-C), 124.8 (d, 3JC-F = 8.1 Hz, Ar-C), 122.4 (d, 4JC-F = 3.3 Hz, Ar-C), 119.3 (d, 2JC-F = 18.7 Hz, Ar-C), 62.7 (d, -OCH3, 4JC-F = 5.5 Hz), 33.6 (-CH2-); HRMS: Calcd for C11H11FN3O2S [M+H]+: 268.0556; found: 268.0550. Calcd for C11H10FN3NaO2S [M+Na]+: 290.0376; found: 290.0371. C22H20F2N6NaO4S2 [2M+Na]+: 557.0854; found: 557.0836.

2.12. 2-(2-(3-Fluoro-2-methoxybenzylidene)hydrazinyl)thiazol-4(5H)-one (4j)

White solid; Yield: 71%; Melting point: 267–269°C; Rf: 0.51 (acetone/n-hexane, 1:3); λmax = 336 nm; FTIR (ATR) cm-1: 2945 (C-H aliphatic stretching), 1710 (C=O stretching), 1635 (C=N stretching), 1585, 1477 (C=C aromatic ring stretching), 1429 (C-H aliphatic bending), 1068 (C-O stretching), 736 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 12.04 (s, 1H, H-N-), 8.53 (s, 1H, H-C=N-), 7.68 (d, 1H, Ar-H, J = 8.0 Hz), 7.39 (app. ddd, 1H, Ar-H, J = 11.8, 8.2, 1.6 Hz), 7.19 (app. td, 1H, Ar-H, J = 8.0, 5.0 Hz), 3.91 (s, 5H, -OCH3, -CH2-, signals overlap); 19F-NMR (375 MHz): δ (ppm) -130.74; 13C-NMR (100 MHz): δ (ppm) 174.8 (C=O), 156.9 (thiazol-4(5H)-one ring C2), 154.4 (Ar-C-OCH3), 150.8 (H-C=N-), 146.9 (d, 3JC-F = 11.7 Hz, Ar-C-F), 129.1 (d, 4JC-F = 2.6 Hz, Ar-C), 124.8 (d, 3JC-F = 8.1 Hz, Ar-C), 122.4 (d, 4JC-F = 3.3 Hz, Ar-C), 119.3 (d, 2JC-F = 18.7 Hz, Ar-C), 62.7 (d, -OCH3, 4JC-F = 5.5 Hz), 33.6 (-CH2-); HRMS: Calcd for C11H11FN3O2S [M+H]+: 268.0556; found: 268.0550. Calcd for C11H10FN3NaO2S [M+Na]+: 290.0376; found: 290.0371. C22H20F2N6NaO4S2 [2M+Na]+: 557.0854; found: 557.0836.

2.13. 2-(2-(4-Hydroxy-3-methoxybenzylidene)hydrazinyl)thiazol-4(5H)-one (4k)

Light grey solid; Yield: 79%; Melting point: 270–271°C; Rf: 0.17 (acetone/n-hexane, 1:3); λmax: 319 nm; FTIR (ATR) cm-1: 3321 (N-H stretching), 2954 (C-H aliphatic stretching), 1695 (C=O stretching), 1635 (C=N stretching), 1600, 1510, 1317, 1471 (C=C aromatic ring stretching), 1433 (C-H aliphatic bending), 1035 (C-O stretching), 736 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 11.88 (s, 1H, H-N-), 9.61 (s, 1H, -OH), 8.27 (s, 1H, H-C=N-), 7.32 (s, 1H, Ar-H), 7.19 (d, 1H, Ar-H, J = 8.2 Hz), 6.85 (d, 1H, Ar-H, J = 8.2 Hz), 3.87 (s, 2H, -CH2-), 3.81 (s, 3H, -OCH3); 13C-NMR (100 MHz): δ (ppm) 174.6 (C=O), 156.7 (thiazol-4(5H)-one ring C2), 149.9 (Ar-C-OH), 148.3 (H-C=N-), 126.1, 122.6, 116.1, 110.9 (Ar-C), 55.9 (-OCH3), 33.4 (-CH2-); HRMS: Calcd for C11H12N3O3S [M+H]+: 266.0599; found: 266.0596. Calcd for C11H11N3NaO3S [M+Na]+: 288.0419; found: 288.0415. C22H22N6NaO6S2 [2M+Na]+: 553.0940; found: 553.0926.

2.14. 2-(2-(3,4-Dimethoxybenzylidene)hydrazinyl)thiazol-4(5H)-one (4l)

White solid; Yield: 78%; Melting point: 251–252°C; Rf: 0.25 (acetone/n-hexane, 1:3); λmax: 334 nm; FTIR (ATR) cm-1: 2947 (C-H aliphatic stretching), 1705 (C=O stretching), 1645 (C=N stretching), 1600, 1510, 1454, 1419 (C=C aromatic ring stretching), 1435 (C-H aliphatic bending), 1138 (C-O stretching), 736 (C-S stretching); 1H-NMR (500 MHz): δ (ppm) 11.92 (s, 1H, H-N-), 8.32 (s, 1H, H-C=N-), 7.36 (s, 1H, Ar-H), 7.30 (app. d, 1H, Ar-H, J = 10.4 Hz), 7.04 (d, 1H, Ar-H, J = 8.5 Hz), 3.88 (s, 2H, -CH2-), 3.81 (s, 3H, -OCH3), 3.80 (s, 3H, -OCH3); 13C-NMR (125 MHz): δ (ppm) 174.6 (C=O), 156.4 (thiazol-4(5H)-one ring C2), 151.6 (Ar-C-OCH3), 149.4 (Ar-C-OCH3), 142.9 (H-C=N-), 127.4, 122.5, 112.1, 109.9 (Ar-C), 56.1 (-OCH3), 55.8 (-OCH3), 33.4 (-CH2-); HRMS: Calcd for C12H14N3O3S [M+H]+: 280.0756; found: 280.0752. Calcd for C12H13N3NaO3S [M+Na]+: 302.0576; found: 302.0568. C24H26N6NaO6S2 [2M+Na]+: 581.1254; found: 581.1246.

2.15. 2-(2-(2-Bromo-4,5-dimethoxybenzylidene)hydrazinyl)thiazol-4(5H)-one (4m)

White solid; Yield: 75%; Melting point: 285–287°C; Rf: 0.40 (acetone/n-hexane, 1:3); λmax: 341 nm; FTIR (ATR) cm-1:) 2956 (C-H aliphatic stretching), 1716 (C=O stretching), 1600 (C=N stretching), 1504, 1460 (C=C aromatic ring stretching), 1431 (C-H aliphatic bending), 1056 (C-O stretching), 738 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 12.02 (s, 1H, H-N-), 8.48 (s, 1H, H-C=N-), 7.47 (s, 1H, Ar-H), 7.23 (s, 1H, Ar-H), 3.90 (s, 2H, -CH2-), 3.85 (s, 3H, -OCH3), 3.81 (s, 3H, -OCH3); 13C-NMR (100 MHz): δ (ppm) 154.4 (Ar-C-OCH3), 152.2 (Ar-C-OCH3), 148.9 (H-C=N-), 125.1, 116.2, 116.0, 109.5 (Ar-C), 56.6 (-OCH3), 55.9 (-OCH3), 33.5 (-CH2-); HRMS: Calcd for C12H13BrN3O3S [M+H]+: 357.9861; found: 357.9849. Calcd for C12H12BrN3NaO3S [M+Na]+: 379.9681; found: 379.9663. C24H24Br2N6NaO6S2 [2M+Na]+: 736.9464; found: 736.9450.

2.16. 2-(2-(6-Methoxy-3,4-dihydronaphthalen-1(2H)-ylidene)hydrazinyl)thiazol-4(5H)-one (4n)

Light grey solid; Yield: 83%; Melting point: 206–208°C; Rf: 0.48 (acetone/n-hexane, 1:3); λmax: 318 nm; FTIR (ATR) cm-1: 3118 (N-H stretching), 2945 (C-H aliphatic stretching), 1703 (C=O stretching), 1598 (C=N stretching), 1494, 1375 (C=C aromatic ring stretching), 1463 (C-H aliphatic bending), 1085 (C-O stretching), 698 (C-S stretching); 1H-NMR (400 MHz): δ (ppm) 8.02 (d, 1H, Ar-H, J = 8.8 Hz), 6.84 (d, 1H, Ar-H, J = 8.8 Hz), 6.77 (s, 1H, Ar-H), 3.84 (s, 2H, -CH2-), 3.78 (s, 3H, -OCH3), 2.82–2.65 (m, 6H, -CH2-CH2-CH2-); 13C-NMR (100 MHz): δ (ppm) 174.4 (C=O ketonic group), 162.9 (thiazol-4(5H)-one ring C2), 160.9 (-OCH3), 142.9 (-C=N-), 126.9, 125.5, 113.7, 113.1 (Ar-C), 55.7 (-OCH3), 33.2 (-CH2-), 29.9 (-CH2-CH2-), 27.3 (-CH2-CH2-), 22.3 (-CH2-CH2-); HRMS: Calcd for C14H16N3O2S [M+H]+: 290.0963; found: 290.0955. Calcd for C14H15N3NaO2S [M+Na]+: 312.0783; found: 312.0782. C28H30N6NaO4S2 [2M+Na]+: 601.1668; found: 601.1661.

2.17. 2-(2-(3,4-Dihydronaphthalen-1(2H)-ylidene)hydrazinyl)thiazol-4(5H)-one (4o)

Brown solid; Yield: 81%; Melting point: 198–199°C; Rf: 0.51 (acetone/n-hexane, 1:3); λmax: 327 nm; FTIR (ATR) cm-1: 3134 (N-H stretching), 2935 (C-H aliphatic stretching), 1703 (C=O stretching), 1602 (C=N stretching), 1450 (C-H aliphatic bending), 1342, 1303 (C=C aromatic ring stretching), 731 (C-S stretching); 1H-NMR (500 MHz): δ (ppm) 11.94 (s, 1H, H-N-), 8.08 (d, 1H, Ar-H, J = 6.3 Hz), 7.32 (t, 1H, Ar-H, J = 7.5 Hz), 7.30–7.24 (m, 1H, Ar-H), 7.22 (d, 1H, Ar-H, J = 7.5 Hz), 3.86 (s, 2H, -CH2-), 2.86–2.81 (m, 2H, -CH2-CH2-), 2.79 (t, 2H, -CH2-CH2-, J = 7.0 Hz), 1.82 (quintet, 2H, -CH2-CH2-CH2-, J = 7.0 Hz); 13C-NMR (125 MHz): δ (ppm) 174.4 (C=O ketonic group), 160.3 (thiazol-4(5H)-one ring C2), 140.9 (H-C=N-), 132.7, 130.2, 129.3, 126.7, 125.0 (Ar-C), 33.2 (-CO-CH2-S-), 29.7 (-CH2-CH2-CH2-), 27.4 (-CH2-CH2-), 22.3 (-CH2-CH2-); HRMS: Calcd for C13H14N3OS [M+H]+: 260.0857; found: 260.0851. Calcd for C13H13N3NaOS [M+Na]+: 282.0617; found: 282.0668. C26H26N6NaO2S2 [2M+Na]+: 541.1456; found: 541.1448.

3. Results & discussion

3.1. Synthesis & chemistry

Thiazol-4(5H)-one derivatives (4a–o) bearing a range of substituents allow investigation of the structure–activity relationships within 4 to be explored. Heating equimolar amounts of thiosemicarbazones, ethyl bromoacetate and 2.0 equivalents of sodium acetate in methanol under reflux for 2–3 h results in the formation of 2-(2-arylidenehydrazinyl)thiazol-4(5H)-ones (4a–o) in good yields (69–83%) (Figure 4).

Figure 4.

Figure 4.

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Synthesis of 2-(2-arylidenehydrazinyl)thiazol-4(5H)-ones (4a–o).

Compounds 4a–o showed the expected physical (melting point, Rf and formula weight via HRMS) and spectroscopic data (UV-vis, FT-IR, 1H- and 13C-NMR). The functional group analysis carried out by FTIR spectroscopy showed absorption bands in the range 3321–3053 cm-1 confirming the presence of an -N–H group in every case. Aliphatic C–H stretching bands are also present in all cases 4a–o between 2987 and 2935 cm-1. The amide C=O groups within the thiazol-4(5H)-ones are ascertained by bands between 1722 and 1695 cm-1. The absorption bands at 1645–1598 cm-1 were assigned to the presence of azomethine linkage. An aliphatic C–H bending mode was observed in the range 1489–1400 cm-1, while the C–S stretching of the thiazol-4(5H)-one ring is indicated by absorption band in the range 746–698 cm-1.

The proposed structures of the synthesized compounds were confirmed by NMR spectroscopy. In their 1H-NMR spectra compounds 4 all show a 1H singlet in the range 11.88–12.13 ppm ascribed to their -N–H units. Additional 1H exchangeable proton signals are apparent for compounds 4g (10.93 ppm) and 4k (9.61 ppm) assigned to their -OH groups. A singlet of one proton in the range 8.27–8.72 ppm is indicative of the azomethine linkage in all compounds. The presence of an -SCH2- group in each case is verified by a 2H singlet in region 3.84–3.98 ppm for all compounds.

The established structures were further verified through 13C-NMR spectroscopy. The carbonyl (amide) group appears as the most downfield signal in the region 174.4–174.8 ppm. A signal in the range 154.8–168.4 ppm is observed due to carbon 2 of the thiazol-4(5H)-one ring. The azomethine functionality is identified by a signal in region 137.0–156.0 ppm. The signal in the region 33.2–33.9 ppm is ascribed to -CH2- group. The molecular formulae of compounds 4 are confirmed, in every case, by HRMS, where the calculated masses of synthesized compounds are in good agreement with observed masses.

The anti-diabetic potential of the synthesized compounds was identified by their α-amylase, anti-glycation, anti-oxidant nature and cyto-toxicity assays. All the biological assays were performed by methods established in our previous studies [26,27].

3.2. Biological screening of 2-(2-arylidenehydrazinyl)thiazol-4(5H)-ones (4a–o)

3.2.1. Theoretical investigation of α-amylase & anti-glycation potential via molecular docking

Molecular docking was used to screen the compounds for their anti-diabetic potential. HPA and HSA were selected as targets as inhibiting α-amylase leads to starch digestion and glucose release in animals. In the presence of higher sugar levels in uncontrolled diabetes [28] the albumin protein gets glycated. 3D structures of HPA and HSA were downloaded from Brookhaven Protein Database (PDB) as pdb files. Molecular docking of selected ligands 4 was performed to predict their potential as α-amylase and glycation inhibitors in comparison to a standard amino-guanidine inhibitor.

Various glycation sites are present in HSA (F1–9), where the protein consists of three structurally homologous domains [29,30]. All ligands bind very well within the active site domains of HSA and form stable complexes with binding energies of -8.92 to -7.18 kcal/mol [far better than the binding energy of standard amino-guanidine (-5.374 kcal/mol). The ligand 4h shows a binding site in domain IIIA with a binding energy of -8.92 kcal/mol. This binding site includes: Glu6, Leu22, Ala26, Phe27, Tyr30, Ser65, Leu66, His67, Thr68, Phe70, Leu74, Gly248, Asp249, Leu250, Leu251, Glu252 amino acid residues (Figure 5). The ligands 4d (-7.55 kcal/mol), 4e (-7.77 kcal/mol), 4f (-7.78 kcal/mol), 4g (-8.15 kcal/mol), 4i (-7.60 kcal/mol) and 4l (-7.52 kcal/mol) showed binding interactions with the binding sites containing: Leu398, Tyr401, Lys402, Asn405, Ala406, Val409, Lys525, Leu529, Leu544, Lys545, Met548, Asp549, Ala552 amino acid residues (Supplementary Table S1). The ligands 4a, 4j, 4m, 4n and 4o bind to a site consisting of Tyr150, Glu153, Ser192, Lys195, Gln196, Lys199, Arg222, Leu238, Val241, His242, Arg257, Leu260, Ala261, Ile264, Ser287, Ile290, Ala291 and Glu292. This includes part of Sudlow site I where Lys199 is responsible for 5% of total glycation in the protein [31,32]. All the ligands 4 bind in the cavity between Leu238 and Ala291, where Arg257 forms stable interactions by hydrogen bonding to N1 and N3 in 4m and N1 of ligand 4j. Here, the ligands enter the gorge avoiding their interactions with Tyr150. Phenylbutazone and warfarin are reported to bind in the same binding site where His242 interactions remain stable even in the presence of bound fatty acids [33].

Figure 5.

Figure 5.

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2D and 3D images of compound 4h interacting with human serum albumin (HSA) and compound 4e human pancreatic α-amylase protein.

The ligand, 4b binds to Asp108, Asn109, Pro110, Leu112, Arg145, His146, Pro147, Tyr148, Ser193, Ala194, Arg197, Glu425, Gln459, Leu463 binding site sharing the glycation site, FA1 in domain IB [34] and FA3 in domain IIIA. His146 is a part of the glycation site (FA1) in domain IB where this is involved in the heme–Fe atom coordination [34]. Previously, Schiff's base derivatives, in other words, triazole Schiff-bases and thiazole-based thiosemicarbazones have been reported to show anti-glycation potential through in silico studies [21,22,35,36] (See Supplementary Figures S1–S13 for docking poses of compounds).

HPA-ligand interactions have been reported at various binding sites in its three domains other than its active sites [37,38]. The ligands 4a, 4b, 4g, 4k, 4l, 4m, 4n and 4o although they do not directly interact with the HPA active site, they do show strong binding energy near its active site, including: Tyr151, Leu162, Ala198, Ser199, Lys200, His201, Glu233, Val234, Ile235, Asp236, Leu237, Gly238Glu240. Ligand 4g show binding energy of -7.49 kcal/mol (Supplementary Table S2), where Ala198, Lys200, Lys237 and Ile235 form H-bonds with ligand molecule, while His201 show π–π interactions. Previously, the residues Ile235 and Glu233 have been found forming H-bonds and His201 charge–π interactions with many ligands [39]. In our case, ligand 4j binds to a site consisting of: Trp58, Tyr62, Tyr151, Leu162, Arg195, Asp197, Ala198, Ser199, Lys200, His201, Glu233, Val234, Ile235, His299 and Asp300 with a binding energy of -7.07 kcal/mol (Supplementary Table S2). The ligand shows π–π interactions with both Tyr62 and His201, while H-bonds are formed to the Arg195, Asp197, Lys200, Glu233, Ile235 and His299 residues. Previously, some natural anthocyanins and their derivatives have shown related binding to the same active site [40]. Ligand 4i binds to a loop region at the C- and N-terminal interface but does not directly disrupt the enzyme's active site. The ligands 4e and 4f bind to Arg124, Phe136, Asn137, Asp138, Cys141, Lys142, Thr143, Gly144, Ser145, Gly146, Asp159, Cys160, Arg161, Leu165, Leu166 and Asp167 amino acids (Figure 5). The ligand 4d binds near to the active site of enzyme possessing Tyr67, Lys68, Leu69, Glu76, Ala128, Val129, Lys178, Glu181, Tyr182 and His185 residues. Many natural and synthetic compounds have been found to interact with active site residues (Trp59, Asp197, Glu233) in HPA [41,42] (See Supplementary Figures S14–S26 for docking poses of compounds).

3.3. α-Amylase inhibition activity

The α-amylase inhibition of compounds (4a–o) was conducted and results of inhibitory potential are presented in the Table 1. Results revealed that all compounds are fairly good inhibitors but found less active than reference in other words, Acarbose (IC50 = 5.89 ± 0.08 μM). The IC50 values of compounds are higher than acarbose and lie between 6.67 ± 0.10 (4b) and 9.26 ± 0.08 μM (4j).

Table 1. Percentage α-amylase inhibition of compounds (4a–o).

Compd. % Age α-amylase inhibition
 IC50 ± SEM (μM)
1 μM 5 μM 10 μM
4a 30.74 47.05 57.29 7.51 ± 0.05
4b 36.84 51.25 65.09 6.67 ± 0.10
4c 33.87 39.55 46.35 9.06 ± 0.10
4d 31.79 41.24 55.02 7.99 ± 0.07
4e 34.35 47.31 61.08 7.15 ± 0.11
4f 35.92 51.10 63.59 6.80 ± 0.11
4g 29.94 38.97 55.91 8.04 ± 0.23
4h 36.21 47.56 56.42 7.52 ± 0.09
4i 34.10 46.33 62.22 7.10 ± 0.08
4j 37.47 40.96 43.85 9.26 ± 0.08
4k 39.43 49.47 59.63 7.14 ± 0.14
4l 34.15 41.67 51.86 8.28 ± 0.17
4m 34.91 48.48 54.59 7.65 ± 0.10
4n 31.98 45.36 57.27 7.69 ± 0.11
4o 38.76 44.21 52.66 8.01 ± 0.05
Acarbose 51.78 62.08 70.79 5.89 ± 0.08
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The results also revealed that inhibitory potential of compounds is dose dependent. The experiment was performed in triplicate using Acarbose as standard.

SEM: Standard error of mean.

3.4. Anti-glycation activity

The anti-glycation potential of compounds (4a–o) was investigated by an in vitro anti-glycation assay. The results (Table 2) indicate that all tested compounds exhibited better anti-glycation potential compared with standard (IC50 = 3.582 ± 0.002 μM). A structure–activity relationship was established which indicate that compounds with electron withdrawing and resonance stabilizing groups present on aryl ring owned better anti-glycation potential. When compared with standard, compound 4m was found most active in this series (IC50 = 1.095 ± 0.002 μM). Moreover, compounds possessing similar groups (-CF3) exhibited similar glycation potential as indicated by 4e (IC50 = 1.366 ± 0.002 μM) and 4f (IC50 = 1.333 ± 0.001 μM). However, the same group present at ortho position (4d) further increased the glycation inhibition ability (IC50 = 1.269 ± 0.003 μM). The results indicated that compounds bearing chloro-group on aryl system 4b (IC50 = 1.513 ± 0.003 μM) and 4g (IC50 = 1.665 ± 0.002 μM) reduced the anti-glycation activity but still more active than standard. The presence of -F and -OCH3 groups on aryl ring exhibited almost similar anti-glycation activity as indicated by 4i (IC50 = 1.569 ± 0.003 μM) and 4j (IC50 = 1.468 ± 0.002 μM). The effect of alkoxy group on the anti-glycation activity indicated that compounds with methoxy group present on aryl ring 4l (IC50 = 1.437 ± 0.002 μM) and 4n (IC50 = 1.418 ± 0.002 μM) exhibited better glycation inhibition potential and this activity is reduced when higher alkoxy group is introduced (4c, IC50 = 1.513 ± 0.002 μM). Other compounds more active than standard include; 4a (2-methyl, IC50 = 1.615 ± 0.001 μM), 4h (2-hydroxy-5-nitro, IC50 = 1.485 ± 0.001 μM), 4k (4-hydroxy-3-methoxy, IC50 = 1.505 ± 0.002 μM) and 4o (3,4-dihydronaphthalen-1(2H)-ylidene, IC50 = 1.544 ± 0.001 μM). It can be concluded that anti-glycation ability is dose dependent for compounds 4 and that the groups present on the aryl ring modify this.

Table 2. Percentage anti-glycation of compounds (4a–o).

Compd. % Age anti-glycation
 IC50 (μM ± SEM)
100 ppm 200 ppm 400 ppm 600 ppm 800 ppm 1000 ppm
4a 86.141 87.297 87.627 88.622 89.483 91.053 1.615 ± 0.001
4b 79.493 80.535 84.038 86.478 89.970 91.985 1.513 ± 0.003
4c 86.223 87.380 88.453 89.200 89.933 90.858 1.513 ± 0.002
4d 87.581 88.908 90.001 90.706 91.317 91.927 1.269 ± 0.003
4e 86.969 88.017 89.140 90.369 91.483 92.154 1.366 ± 0.002
4f 89.319 91.303 91.916 92.706 93.761 94.698 1.333 ± 0.001
4g 64.519 70.235 73.388 76.208 81.395 86.015 1.665 ± 0.002
4h 71.876 74.777 79.150 84.843 88.011 90.656 1.485 ± 0.001
4i 79.410 79.906 83.487 85.236 85.834 86.513 1.569 ± 0.003
4j 83.999 86.509 88.774 90.893 91.817 92.516 1.468 ± 0.002
4k 85.621 86.804 87.333 88.685 90.037 90.852 1.505 ± 0.002
4l 81.346 84.209 85.600 87.277 90.269 92.095 1.437 ± 0.002
4m 84.334 86.264 89.246 90.842 91.775 93.167 1.095 ± 0.002
4n 79.881 81.122 83.271 85.252 88.441 90.107 1.418 ± 0.002
4o 81.886 84.099 85.202 88.829 90.438 91.535 1.544 ± 0.001
Amino–guanidine (control) 81.920 84.269 85.486 89.608 91.205 92.913 3.582 ± 0.002
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SEM: Standard error of mean.

3.5. Free radical scavenging activity

The anti-oxidant behavior of compounds (4a–o) was studied by DPPH assay and compared with ascorbic acid (IC50 = 8.04 ± 0.03 mM) as a standard. Only one compound (4h) exhibited significant anti-oxidant potential (IC50 = 13.35 ± 0.10 mM). No anti-oxidant response was apparent for other examples of 4 at concentrations of 3–15 mM. The percentage anti-oxidant potential was less than 50%, hence IC50 values were not calculated for them.

3.6. In vitro hemolytic activity

The cyto-toxic nature of compounds (4a–o) was examined by hemolytic assay. The compounds were treated with human red blood cells (RBCs) and the results are presented in Table 3. Compound 4k was found safe to human erythrocytes at all tested concentrations. The compounds 4a, 4b, 4e, 4f and 4g showed minimum toxicity, inducing less than 1% lysis in RBCs at minimum tested concentration. All other compounds were found to be toxic to human blood cells (7–31% hemolysis induced by 50 μM 4).

Table 3. Percentage hemolysis of compounds (4a–o).

Compd. % hemolysis
10 μM 50 μM 100 μM
4a 0.99 1.59 11.15
4b 0.59 7.29 32.24
4c 3.28 24.56 37.44
4d 1.49 13.03 29.94
4e 0.87 12.10 34.92
4f 0.68 19.83 38.37
4g 0.39 1.92 6.88
4h 8.76 21.30 40.18
4i 1.26 16.52 37.50
4j 1.53 20.12 37.28
4k 0.00 0.00 1.08
4l 3.36 20.83 43.75
4m 7.93 31.04 48.92
4n 3.81 26.17 43.51
4o 2.48 20.68 44.46
Triton X-100 100 100 100
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4. Conclusion

In the current study, 15 thiazol-4(5H)-ones were synthesized and evaluated for their potential anti-diabetic nature. All synthesized compounds were tested for their α-amylase inhibition potential and found good inhibitors but not better than the standard. This indicated that tested compounds do not express anti-diabetic potential via α-amylase inhibition mechanism. All 15 analogs were the most potent glycation inhibitors compared with standard. This indicated that tested compounds manage diabetes via glycation inhibition. When further evaluated for cyto-toxicity, only one compound was found safe to human erythrocytes, hence it might serve as a useful lead for further research in diabetes management. The experimental results were further supported with theoretical docking studies. Hence, it is concluded that modification around thiazol-4(5H)-one ring might help to find better anti-diabetic agent.

5. Twitter Text

  • Simple, cost-effective and high-yielding Hantzsch's synthetic approach was used to synthesize thiazole-4-one based derivatives.

  • Spectroscopic techniques (UV-Vis, FTIR, 1H-, 13C-NMR and HRMS) were used to justify the structure of proposed analogs.

  • Anti-diabetic potential of all synthesized compounds was determined with different biological assays including α-amylase, anti-glycation and anti-oxidant.

  • Cyto-toxic behavior of synthetic targets was determined with hemolytic assays.

  • Ligand receptor interactions were evaluated with the help of molecular docking studies.

Supplementary Material

Supplementary Figures S1-S26 and Supplementary Tables S1-S2
IFMC_A_2342700_SM0001.docx (19.5MB, docx)

Acknowledgments

The authors thank the Researchers Supporting Project number (RSP2024R29) King Saud University, Riyadh, Saudi Arabia.

Supplemental material

Supplemental data for this article can be accessed at https://doi.org/10.1080/17568919.2024.2342700

Author contributions

I, M Haroon, confirm that all authors played their role in this work and briefed as under; H Mehmood: performed the synthetic work and characterized the compounds, M Haroon: compiled the manuscript and corresponding author. T Akhtar: As supervisor of the first author, refined the paper and sharing the correspondence besides being project designer. S Woodward: supported in characterization and interpretation of data. S Haq and SM Alshehri: performed docking and its writeup.

Financial disclosure

The authors have no financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Competing interests disclosure

The authors have no competing interests with any organization or entity with the materials discussed in the manuscript.

Writing disclosure

No writing assistance was utilized in the production of this manuscript.

References

Papers of special note have been highlighted as: • of interest; •• of considerable interest

  • 1.Khalil NA, Ahmed EM, El-Nassan HB. Synthesis, characterization, and biological evaluation of certain 1, 3-thiazolone derivatives bearing pyrazoline moiety as potential anti-breast cancer agents. Med Chem Res. 2013;22:1021–1027. doi: 10.1007/s00044-012-0098-7 [DOI] [Google Scholar]
  • 2.Véniant MM, Hale C, Hungate RW, et al. Discovery of a potent, orally active 11β-hydroxysteroid dehydrogenase type 1 inhibitor for clinical study: Identification of (S)-2-((1S,2S,4R)-Bicyclo[2.2.1]heptan-2-ylamino)-5-isopropyl-5-methylthiazol-4(5H)-one (AMG 221). J Med Chem. 2010;53(11):4481–4487. doi: 10.1021/jm100242d [DOI] [PubMed] [Google Scholar]
  • 3.Mielgo A, Palomo C. 1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis. Beilstein J Org Chem. 2016;12(1):918–936. doi: 10.3762/bjoc.12.90 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4.Shelke RN, Pansare DN, Sarkate AP, et al. Synthesis of (Z)-5-(substituted benzylidene)-2-((substituted phenyl) amino) thiazol-4(5H)-one analogs with antitubercular activity. J Taibah Univ Sci. 2019;13(1):678–686. doi: 10.1080/16583655.2019.1622846 [DOI] [Google Scholar]
  • 5.Melato S, Prosperi D, Coghi P, et al. A combinatorial approach to 2,4,6-trisubstituted triazines with potent antimalarial activity: combining conventional synthesis and microwave-assistance. ChemMedChem: Chem Enab Drug Discov. 2008;3(6):873–876. [DOI] [PubMed] [Google Scholar]
  • 6.Aziz MW, Kamal AM, Mohamed KO, et al. Design, synthesis and assessment of new series of quinazolinone derivatives as EGFR inhibitors along with their cytotoxic evaluation against MCF7 and A549 cancer cell lines. Bioorg Med Chem Lett. 2021;41:127987. doi: 10.1016/j.bmcl.2021.127987 [DOI] [PubMed] [Google Scholar]
  • 7.Zhou H, Wu S, Zhai S, et al. Design, synthesis, cytoselective toxicity, structure-activity relationships, and pharmacophore of thiazolidinone derivatives targeting drug-resistant lung cancer cells. J Med Chem. 2008;51(5):1242–1251. doi: 10.1021/jm7012024 [DOI] [PubMed] [Google Scholar]
  • 8.Kang KH, Lee B, Son S, et al. (Z)-2-(Benzo[d]thiazol-2-ylamino)-5-(substituted benzylidene)thiazol-4(5H)-one derivatives as novel tyrosinase inhibitors. Biol Pharm Bulletin. 2015;38(8):1227–1233. doi: 10.1248/bpb.b15-00300 [DOI] [PubMed] [Google Scholar]
  • 9.Robertson MJ, Horatscheck A, Sauer S, et al. 5-Aryl-2-(naphtha-1-yl)sulfonamido-thiazol-4(5H)-ones as clathrin inhibitors. Org Biomol Chem. 2016;14(47):11266–11278. doi: 10.1039/C6OB02308H [DOI] [PubMed] [Google Scholar]
  • 10.Kumar V, Sharma A, Chander Sharma P. Synthesis of some novel 2, 5-disubstituted thiazolidinones from a long chain fatty acid as possible anti-inflammatory, analgesic and hydrogen peroxide scavenging agents. J Enzyme Inhib Med Chem. 2011;26(2):198–203. doi: 10.3109/14756366.2010.489897 [DOI] [PubMed] [Google Scholar]
  • 11.Diurno MV, Mazzoni O, Piscopo E, et al. Synthesis and antihistaminic activity of some thiazolidin-4-ones. J Med Chem. 1992;35(15):2910–2912. doi: 10.1021/jm00093a025 [DOI] [PubMed] [Google Scholar]
  • 12.Jean DJ St., Yuan C, Bercot EA, et al. 2-(S)-Phenethylaminothiazolones as potent, orally efficacious inhibitors of 11β-hydroxysteriod dehydrogenase type 1. J Med Chem. 2007;50(3):429–432. doi: 10.1021/jm061214f [DOI] [PubMed] [Google Scholar]
  • 13.Yuan C, Jean DJS Jr, Liu Q, et al. The discovery of 2-anilinothiazolones as 11β-HSD1 inhibitors. Bioorg Med Chem Lett. 2007;17(22):6056–6061. doi: 10.1016/j.bmcl.2007.09.070 [DOI] [PubMed] [Google Scholar]
  • 14.Studzińska R, Kołodziejska R, Kupczyk D, et al. A novel derivatives of thiazol-4(5H)-one and their activity in the inhibition of 11β-hydroxysteroid dehydrogenase type 1. Bioorg Chem. 2018;79:115–121. doi: 10.1016/j.bioorg.2018.04.014 [DOI] [PubMed] [Google Scholar]
  • 15.Johansson L, Fotsch C, Bartberger MD, et al. 2-Amino-1,3-thiazol-4(5H)-ones as potent and selective 11β-hydroxysteroid dehydrogenase Type 1 inhibitors: enzyme- ligand co-crystal structure and demonstration of pharmacodynamic effects in C57Bl/6 mice. J Med Chem. 2008;51(10):2933–2943. doi: 10.1021/jm701551j [DOI] [PubMed] [Google Scholar]
  • 16.International Diabetes Federation . IDF Diabetes Atlas, 10th edn. Brussels, Belgium; 2021. [Google Scholar]
  • 17.Subahan SF, Kumar JS, Sree BT, et al. A short review on insulin therapy. Pharm Sci. 2023;3(2):147–150. [Google Scholar]
  • 18.Milne N, Di Rosa F. The diabetes review: A guide to the basics. Updated December 2020. J Diabetes Nurs. 2020;24(6):161. [Google Scholar]
  • 19.Okur ME, Karantas ID, Siafaka PI. Diabetes mellitus: A review on pathophysiology, current status of oral medications and future perspectives. ACTA Pharmaceutica Sciencia. 2017;55(1):61–82. doi: 10.23893/1307-2080.APS.0555 [DOI] [Google Scholar]
  • 20.Murphy GJ, Holder JC. PPAR-γ agonists: therapeutic role in diabetes, inflammation and cancer. Trends Pharmacol Sci. 2000;21(12):469–674. doi: 10.1016/S0165-6147(00)01559-5 [DOI] [PubMed] [Google Scholar]; • Explains how PPAR-γ agonists play their role in diabetes.
  • 21.Mehmood H, Akhtar T, Haroon M, et al. Synthesis of hydrazinylthiazole carboxylates: a mechanistic approach for treatment of diabetes and its complications. Future Med Chem. 2023;15(13):1149–1165. doi: 10.4155/fmc-2023-0136 [DOI] [PubMed] [Google Scholar]; •• A very important investigation, how hydrazinyl-based moiety mechanistically involves in treatment of diabetes.
  • 22.Iqbal Y, Akhtar T, Haroon M, et al. 4-Adamantyl-(2-(arylidene) hydrazinyl) thiazoles as potential antidiabetic agents: experimental and docking studies. Future Med Chem. 2023;15(7):599–613. doi: 10.4155/fmc-2023-0010 [DOI] [PubMed] [Google Scholar]
  • 23.Pulici M, Quartieri F. Traceless solid-phase synthesis of 2-amino-5-alkylidene-thiazol-4-ones. Tetrahedron Lett. 2005;46(14):2387–2391. doi: 10.1016/j.tetlet.2005.02.059 [DOI] [Google Scholar]; • This paper is important as it describes one of the unique synthetic method for thiazol-4-ones.
  • 24.Barzen S, Rödl CB, Lill A, et al. Synthesis and biological evaluation of a class of 5-benzylidene-2-phenyl-thiazolinones as potent 5-lipoxygenase inhibitors. Bioorg Med Chem. 2012;20(11):3575–3583. doi: 10.1016/j.bmc.2012.04.003 [DOI] [PubMed] [Google Scholar]
  • 25.Mehmood H, Musa M, Woodward S, et al. Design, and synthesis of selectively anticancer 4-cyanophenyl substituted thiazol-2-ylhydrazones. RSC Adv. 2022;12(52):34126–34141. doi: 10.1039/D2RA03226K [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 26.Mehmood H, Akhtar T, Haroon M, et al. Synthesis of arylidenehydrazinyl-4-methoxyphenylthiazole derivatives: docking studies, probing Type II diabetes complication management agents. Chem Biodiversity. 2022;19(11):e202200824. doi: 10.1002/cbdv.202200824 [DOI] [PubMed] [Google Scholar]; • This explains how arylidenehydrazinyl-based thiazole compounds act as a leading pharmcophore to control diabetes.
  • 27.Mehmood H, Haroon M, Akhtar T, et al. Synthesis and molecular docking studies of 5-acetyl-2-(arylidenehydrazin-1-yl)-4-methyl-1, 3-thiazoles as α-amylase inhibitors. J Mol Struct. 2022;1250:131807. doi: 10.1016/j.molstruc.2021.131807 [DOI] [Google Scholar]
  • 28.Malik A, Mehmood MH, Fayyaz-ur-Rehman M. Journey of 100 years of insulin discovery, from past to present: an overview. Multidiscip Rev. 2021;1:19–34. [Google Scholar]; • An important review about diabetic drugs.
  • 29.Di Muzio E, Polticelli F, Trezza V, et al. Imatinib binding to human serum albumin modulates heme association and reactivity. Archiv Biochem Biophys. 2014;560:100–112. doi: 10.1016/j.abb.2014.07.001 [DOI] [PubMed] [Google Scholar]
  • 30.Shahzadi K, Haroon M, Khalid M, et al. Synthesis and in silico docking studies of ethyl 2-(2-Arylidene-1-alkylhydrazinyl)thiazole-4-carboxylates as antiglycating agents. Chem Biodivers. 2022;19(2):e202100581. doi: 10.1002/cbdv.202100581 [DOI] [PubMed] [Google Scholar]
  • 31.Rondeau P, Bourdon E. The glycation of albumin: structural and functional impacts. Biochimie. 2011;93(4):645–658. doi: 10.1016/j.biochi.2010.12.003 [DOI] [PubMed] [Google Scholar]; •• This paper highlights the glycation process of albumin protein.
  • 32.Rabbani G, Ahn SN. Structure, enzymatic activities, glycation and therapeutic potential of human serum albumin: a natural cargo. Int J Biol Macromol. 2019;123:979–990. doi: 10.1016/j.ijbiomac.2018.11.053 [DOI] [PubMed] [Google Scholar]
  • 33.Ghuman J, Zunszain PA, Petitpas I, et al. Structural basis of the drug-binding specificity of human serum albumin. J Mol Biol. 2005;353(1):38–52. doi: 10.1016/j.jmb.2005.07.075 [DOI] [PubMed] [Google Scholar]
  • 34.Ascenzi P, di Masi A, Fanali G, et al. Heme-based catalytic properties of human serum albumin. Cell Death Discov. 2015;1(1):15025. doi: 10.1038/cddiscovery.2015.25 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 35.Shaikh M, Siddiqui S, Zafar H, et al. Antiglycation activity of triazole Schiff's bases against fructosemediated glycation: in vitro and in silico study. Med Chem. 2020;16(4):575–591. doi: 10.2174/1573406415666190212105718 [DOI] [PubMed] [Google Scholar]
  • 36.Mehmood H, Akhtar T, Haroon M, et al. Synthesis of fluorinated hydrazinylthiazole derivatives: a virtual and experimental approach to diabetes management. ACS Omega. 2023;8(12):11433–11446. doi: 10.1021/acsomega.3c00265 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 37.Brayer GD, Luo Y, Withers SG. The structure of human pancreatic alpha-amylase at 1.8 A resolution and comparisons with related enzymes. Protein Sci. 1995;4(9):1730–1742. doi: 10.1002/pro.5560040908 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 38.Dandekar PD, Kotmale AS, Chavan SR, et al. Insights into the inhibition mechanism of human pancreatic α-amylase, a Type 2 diabetes target, by dehydrodieugenol B isolated from Ocimum tenuiflorum. ACS Omega. 2021;6(3):1780–1786. doi: 10.1021/acsomega.0c00617 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 39.Hawash M, Jaradat N, Shekfeh S, et al. Molecular docking, chemo-informatic properties, alpha-amylase, and lipase inhibition studies of benzodioxol derivatives. BMC Chem. 2021;15(1):40. doi: 10.1186/s13065-021-00766-x [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 40.Xie L, Mo J, Ni J, et al. Structure-based design of human pancreatic amylase inhibitors from the natural anthocyanin database for Type 2 diabetes. Food Funct. 2020;11(4):2910–2923. doi: 10.1039/C9FO02885D [DOI] [PubMed] [Google Scholar]
  • 41.Akinyede KA, Oyewusi HA, Hughes GD, et al. In vitro evaluation of the anti-diabetic potential of aqueous acetone Helichrysum petiolare extract (AAHPE) with molecular docking relevance in diabetes mellitus. Molecules. 2021;27(1):155. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 42.Lo Piparo E, Scheib H, Frei N, et al. Flavonoids for controlling starch digestion: structural requirements for inhibiting human α-amylase. J. Medicin. Chem. 2008;51(12):3555–3561. [DOI] [PubMed] [Google Scholar]

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