Indole-3-acetamides: As Potential Antihyperglycemic and Antioxidant Agents; Synthesis, <i>In Vitro</i> α-Amylase Inhibitory Activity, Structure–Activity Relationship, and <i>In Silico</i> Studies

Abstract

Indole-3-acetamides (<b>1-24</b>) were synthesized via coupling of indole-3-acetic acid with various substituted anilines in the presence of coupling reagent 1,1-carbonyldiimidazole. The structures of synthetic molecules were elucidated through different spectroscopic techniques including electron ionization-mass spectroscopy (EI-MS), ¹H-, ¹³C NMR, and high-resolution EI-MS (HREI-MS). These compounds were screened for their antihyperglycemic and antioxidant potentials. All compounds displayed good to moderate inhibition against α-amylase enzyme with IC₅₀ values ranging between 1.09 ± 0.11 and 2.84 ± 0.1 μM compared to the standard acarbose (IC₅₀ = 0.92 ± 0.4 μM). Compound <b>15</b> (IC₅₀ = 1.09 ± 0.11 μM) was the most active compound of the series and exhibited good inhibition against α-amylase; in addition, this compound also exhibited good antioxidant potential with IC₅₀ values of 0.35 ± 0.1 and 0.81 ± 0.25 μM in 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, respectively. The binding interactions of synthetic molecules with the enzyme's active site were confirmed via <i>in silico</i> studies. The current study had identified a number of lead molecules as potential antihyperglycemic and antioxidant agents.