Synthesis and Molecular Docking Studies of Novel Biheterocyclic Propanamides as Antidiabetic Agents Having Mild Cytotoxicity

The aim of this work was to bring forth some new hybrid molecules having pharmacologically potent indole and 1,3,4-oxadiazole heterocyclic moieties unified with a propanamide entity. The synthetic methodology was initiated by esterification of 2-(1H-indol-3-yl)acetic acid (1) in a catalytic amount of sulfuric acid and ethanol in excess, to form ethyl 2-(1H-indol-3-yl)acetate (2), which was converted to 2-(1H-indol-3-yl)acetohydrazide (3) and further transformed to 5-(1H-indole-3-yl-methyl)-1,3,4-oxadiazole-2-thiol (4). 3-Bromopropanoyl chloride (5) was reacted with various amines (6a-s) in aqueous alkaline medium to generate a series of electrophiles, 3-bromo-N-(substituted)propanamides (7a-s), and these were further reacted with nucleophile 4 in DMF and NaH base to yield the targeted N-(substituted)-3-{(5-(1H-indol-3-ylmethyl)-1,3,4-oxadiazol-2-yl)sulfanyl}propanamides (8a-s). The chemical structures of these biheterocyclic propanamides were confirmed by IR, 1H NMR, 13C NMR, and EI-MS spectral techniques. These compounds were evaluated for their enzyme inhibitory potentials against the α-glucosidase enzyme, where the compound 8l showed promising enzyme inhibitory potential with an IC50 value less than that of the standard acarbose. Molecular docking results of these molecules were coherent with the results of their enzyme inhibitory potentials. Cytotoxicity was assessed by the percentage of hemolytic activity method, and these compounds generally exhibited very low values as compared to the reference standard, Triton-X. Hence, some of these biheterocyclic propanamides might be considered as salient therapeutic agents in further stages of antidiabetic drug development.