Novel hydrazone schiff's base derivatives of polyhydroquinoline: synthesis, in vitro prolyl oligopeptidase inhibitory activity and their Molecular docking study.

This research work reports the synthesis of new derivatives of the hydrazone Schiff bases (1-17) based on polyhydroquinoline nucleus through multistep reactions. HR-ESIMS,1H- and 13C-NMR spectroscopy were used to structurally infer all of the synthesized compounds and lastly evaluated for prolyl oligopeptidase inhibitory activity. All the prepared products displayed good to excellent inhibitory activity when compared with standard z-prolyl-prolinal. Three derivatives 3, 15 and 14 showed excellent inhibition with IC50 values 3.21 ± 0.15 to 5.67 ± 0.18 µM, while the remaining 12 compounds showed significant activity. Docking studies indicated a good correlation with the biochemical potency of compounds estimated in the in-vitro test and showed the potency of compounds 3, 15 and 14. The MD simulation results confirmed the stability of the most potent inhibitors 3, 15 and 14 at 250 ns using the parameters RMSD, RMSF, Rg and number of hydrogen bonds. The RMSD values indicate the stability of the protein backbone in complex with the inhibitors over the simulation time. The RMSF values of the binding site residues indicate that the potent inhibitors contributed to stabilizing these regions of the protein, through formed stable interactions with the protein. The Rg. analysis assesses the overall size and compactness of the complexes. The maintenance of stable hydrogen bonds suggests the existence of favorable binding interactions. SASA analysis suggests that they maintained stable conformations without large-scale exposure to the solvent. These results indicate that the ligand-protein interactions are stable and could be exploited to design new drugs for disease treatment.Communicated by Ramaswamy H. Sarma.

Polyhydroquinoline derivatives for diabetic management: synthesis, in vitro and in silico approaches.

Background: Medication used to treat Type 2 diabetes by decreasing the absorption of carbohydrates in the intestine consists of α-glucosidase inhibitors. Polyhydroquinoline derivatives have attracted interest as excellent antidiabetic agents. Methods: Polyhydroquinoline derivatives (1-17) were synthesized and tested for in vitro α-glucosidase inhibitory activity. Results: All the synthesized compounds exhibited excellent to good inhibitory activity, having IC50 values from 1.23 ± 0.03 to 73.85 ± 0.61 µM, compared with the standard drug, acarbose. The binding mechanism of these derivatives with α-glucosidase was deduced by docking studies and indicated that a slight variation in the orientation of compounds, affects their binding capability. Conclusion: In order to find new antidiabetic drugs, this study has discovered prospective lead candidates.

Bio-Oriented Synthesis of Novel Polyhydroquinoline Derivatives as α-Glucosidase Inhibitor for Management of Diabetes.

Polyhydroquinoline derivatives (1-15) were synthesized through an unsymmetrical Hantzsch reaction in excellent yields by treating 3,5-dibromo-4-hydroxybenzaldehyde, dimedone, ammonium acetate, and ethyl acetoacetate in ethanol solvent. The structures of the synthesized compounds (1-15) were deduced through different spectroscopic techniques such as 1H NMR, 13C NMR, and HR-ESI-MS. The synthesized products were tested for their α-glucosidase inhibitory activity where compounds 11 (IC50 = 0.56 ± 0.01 µM), 10 (IC50 = 0.94 ± 0.01 µM), 4 (IC50 = 1.47 ± 0.01 µM), 2 (IC50 = 2.20 ± 0.03 µM), 6 (IC50 = 2.20 ± 0.03 µM), 12 (IC50 = 2.22 ± 0.07 µM), 7 (IC50 = 2.76 ± 0.04 µM), 9 (IC50 = 2.78 ± 0.03 µM), and 3 (IC50 = 2.88 ± 0.05 µM) exhibited high potential for the inhibition of α-glucosidase, while the rest of the compounds (8, 5, 14, 15, and 13) showed significant α-glucosidase inhibitory potential with IC50 values of 3.13 ± 0.10, 3.34 ± 0.06, 4.27 ± 0.13, 6.34 ± 0.15, and 21.37 ± 0.61 µM, respectively. Among the synthesized series, two compounds, i.e., 11 and 10, showed potent α-glucosidase inhibitory potential higher than the standard. All the compounds were compared with standard drug "acarbose" (IC50 = 873.34 ± 1.67 µM). An in silico method was used to predict their mode of binding within the active site of enzyme to understand their mechanism of inhibition. Our in silico observation complements with the experimental results.