Shafqat Hussain

Triazinoindole analogs as potent inhibitors of α-glucosidase: synthesis, biological evaluation and molecular docking studies.

A new series of triazinoindole analogs 1-11 were synthesized, characterized by EI-MS and (1)H NMR, evaluated for α-glucosidase inhibitory potential. All eleven (11) analogs showed different range of α-glucosidase inhibitory potential with IC50 value ranging between 2.46±0.008 and 312.79±0.06 μM when compared with the standard acarbose (IC50, 38.25±0.12 μM). Among the series, compounds 1, 3, 4, 5, 7, 8, and 11 showed excellent inhibitory potential with IC50 values 2.46±0.008, 37.78±0.05, 28.91±0.0, 38.12±0.04, 37.43±0.03, 36.89±0.06 and 37.11±0.05 μM respectively. All other compounds also showed good enzyme inhibition. The binding modes of these analogs were confirmed through molecular docking.

Synthesis and β-glucuronidase inhibitory activity of 2-arylquinazolin-4(3H)-ones.

2-Arylquinazolin-4(3H)-ones 1-25 were synthesized by reacting anthranilamide with various benzaldehydes using CuCl2·2H2O as a catalyst in ethanol under reflux. Synthetic 2-arylquinazolin-4(3H)-ones 1-25 were evaluated for their β-glucuronidase inhibitory potential. A trend of inhibition IC50 against the enzyme in the range of 0.6-198.2μM, was observed and compared with the standard d-saccharic acid 1,4-lactone (IC50=45.75±2.16μM). Compounds 13, 19, 4, 12, 14, 22, 23, 25, 15, 8, 17, 11, 21, 1, 3, 18, 9, 2, and 24 with the IC50 values within the range of 0.6-44.0μM, indicated that the compounds have superior activity than the standard. The compounds showed no cytotoxic effects against PC-3 cells. A structure-activity relationship is established.

Evaluation of bisindole as potent β-glucuronidase inhibitors: Synthesis and in silico based studies

Bisindole analogs 1-17 were synthesized and evaluated for their in vitro β-glucuronidase inhibitory potential. Out of seventeen compounds, the analog 1 (IC50=1.62±0.04 μM), 6 (IC50=1.86±0.05 μM), 10 (IC50=2.80±0.29 μM), 9 (IC50=3.10±0.28 μM), 14 (IC50=4.30±0.08 μM), 2 (IC50=18.40±0.09 μM), 19 (IC50=19.90±1.05 μM), 4 (IC50=20.90±0.62 μM), 7 (IC50=21.50±0.77 μM), and 3 (IC50=22.30±0.02 μM) showed superior β-glucuronidase inhibitory activity than the standard (d-saccharic acid 1,4-lactone, IC50=48.40±1.25 μM). In addition, molecular docking studies were performed to investigate the binding interactions of bisindole derivatives with the enzyme. This study has identified a new class of potent β-glucouronidase inhibitors.

Oxadiazoles and thiadiazoles: Novel α-glucosidase inhibitors

Oxadiazoles and thiadiazoles 1-37 were synthesized and evaluated for the first time for their α-glucosidase inhibitory activities. As a result, fifteen of them 1, 4, 5, 7, 8, 13, 17, 23, 25, 30, 32, 33, 35, 36 and 37 were identified as potent inhibitors of the enzyme. Kinetic studies of the most active compounds (oxadiazoles 1, 23 and 25, and thiadiazoles 35 and 37) were carried out to determine their mode of inhibition and dissociation constants Ki. The most potent compound of the oxadiazole series (compound 23) was found to be a non-competitive inhibitor (Ki=4.36±0.017 μM), while most potent thiadiazole 35 was identified as a competitive inhibitor (Ki=6.0±0.059 μM). The selectivity and toxicity of these compounds were also studied by evaluating their potential against other enzymes, such as carbonic anhydrase-II and phosphodiesterase-I. Cytotoxicity was evaluated against rat fibroblast 3T3 cell line. Interestingly, these compounds were found to be inactive against other enzymes, exhibiting their selectivity towards α-glucosidase. Inhibition of α-glucosidase is an effective strategy for controlling post-prandial hyperglycemia in diabetic patients. α-Glucosidase inhibitors can also be used as anti-obesity and anti-viral drugs. Our study identifies two novel series of potent α-glucosidase inhibitors for further investigation.

Synthesis and structure–activity relationship of thiobarbituric acid derivatives as potent inhibitors of urease

A series of thiobarbituric acid derivatives 1-27 were synthesized and evaluated for their urease inhibitory potential. Exciting results were obtained from the screening of these compounds 1-27. Compounds 5, 7, 8, 11, 16, 17, 22, 23 and 24 showed excellent urease inhibition with IC50 values 18.1 ± 0.52, 16.0 ± 0.45, 16.0 ± 0.22, 14.3 ± 0.27, 6.7 ± 0.27, 10.6 ± 0.17, 19.2 ± 0.29, 18.2 ± 0.76 and 1.61 ± 0.18 μM, respectively, much better than the standard urease inhibitor thiourea (IC₅₀=21 ± 0.11 μM). Compound 3, 4, 10, and 26 exhibited comparable activities to the standard with IC₅₀ values 21.4 ± 1.04 and 21.5 ± 0.61 μM, 22.8 ± 0.32, 25.2 ± 0.63, respectively. However the remaining compounds also showed prominent inhibitory potential The structure-activity relationship was established for these compounds. This study identified a novel class of urease inhibitors. The structures of all compounds were confirmed through spectroscopic techniques such as EI-MS and (1)H NMR.

5-Bromo-2-aryl benzimidazole derivatives as non-cytotoxic potential dual inhibitors of α-glucosidase and urease enzymes

On the basis of previous report on promising α-glucosidase inhibitory activity of 5-bromo-2-aryl benzimidazole derivatives, these derivatives were further screened for urease inhibitory and cytotoxicity activity in order to get more potent and non-cytotoxic potential dual inhibitor for the patients suffering from diabetes as well as peptic ulcer. In this study, all compounds showed varying degree of potency in the range of (IC50=8.15±0.03-354.67±0.19μM) as compared to standard thiourea (IC50=21.25±0.15μM). It is worth mentioning that derivatives 7 (IC50=12.07±0.05μM), 8 (IC50=10.57±0.12μM), 11 (IC50=13.76±0.02μM), 14 (IC50=15.70±0.12μM) and 22 (IC50=8.15±0.03μM) were found to be more potent inhibitors than standard. All compounds were also evaluated for cytotoxicity towards 3T3 mouse fibroblast cell line and found to be completely non-toxic. Previously benzimidazole 1-25 were also showed α-glucosidase inhibitory potential. In silico studies were performed on the lead molecules i.e.2, 7, 8, 11, 14, and 22, in order to rationalize the binding interaction of compounds with the active site of urease enzyme.

Syntheses, in vitro evaluation and molecular docking studies of 5-bromo-2-aryl benzimidazoles as α -glucosidase inhibitors

Based on the previous reports on α-glucosidase inhibitory activity of benzimidazole class, we intend to evaluate further this class as potential inhibitors of α-glucosidase enzyme. Thus, in the current study synthesis of 5-bromo-2-aryl benzimidazole derivatives 1–25 was carried out. All the synthetic compounds were characterized by different spectroscopic techniques EIMS, HRMS, 1H-NMR, and 13C-NMR. Molecular docking was also performed on the selected compounds 1, 4, 7, and 17 having varying substitution pattern in order to understand the molecular interaction of molecules with the active site of the enzyme. All compounds were evaluated for their in vitro α-glucosidase inhibitory activities. Twenty-three compounds out of twenty-five showed excellent to moderate activity in the range of IC50 = 12.4–103.2 μM. Inhibitory results were compared with the standard drug acarbose (IC50 = 38.25 ± 0.12 μM). Compounds 1 (IC50 = 37.82 ± 0.08 μM), 9 (IC50 = 37.76 ± 0.05 μM), 12 (IC50 = 24.96 ± 0.09 μM), 16 (IC50 = 21.15 ± 0.08 μM) and 17 (IC50 = 8.34 ± 0.02 μM) showed excellent inhibition as compared to standard drug acarbose (IC50 = 38.25 ± 0.12 μM). Especially, 17 (IC50 = 8.34 ± 0.02 μM) was found to be five-fold more active than the standard.

Synthetic nicotinic/isonicotinic thiosemicarbazides: In vitro urease inhibitory activities and molecular docking studies

Nicotinic and isonicotinic thiosemicarbazide or hydrazine carbothioamides 3-27 were synthesized and the structures of synthetic compounds were elucidated by various spectroscopic techniques such as EI-MS, 1H-, and 13C NMR. Synthetic derivatives were evaluated for their urease inhibitory activity which revealed that except few all derivatives demonstrated excellent inhibition in the range of IC50 values of 1.21-51.42 μM as compared to the standard thiourea (IC50 = 21.25 ± 0.13 μM). Among the twenty-five synthetic derivatives nineteen 1-5, 7, 8, 10, 12, 14-18, 20-22, 24-27 were found to be more active showing IC50 values between 1.13 and 19.74 μM showing superior activity than the standard. Limited structure-activity relationship demonstrated that the positions of substituent as well as position of nitrogen in pyridine ring are very important for inhibitory activity of this class of compound. To verify these interpretations, in silico study was also performed. A good correlation was obtained between the biological evaluation of active compounds and docking study.