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

Indole-3-acetamides (1-24) 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), H-1-, C-13 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 alpha-amylase enzyme with IC50 values ranging between 1.09 +/- 0.11 and 2.84 +/- 0.1 mu M compared to the standard acarbose (IC50 = 0.92 +/- 0.4 mu M). Compound 15 (IC50 = 1.09 +/- 0.11 mu M) was the most active compound of the series and exhibited good inhibition against alpha-amylase; in addition, this compound also exhibited good antioxidant potential with IC50 values of 0.35 +/- 0.1 and 0.81 +/- 0.25 mu M 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 in silico studies. The current study had identified a number of lead molecules as potential antihyperglycemic and antioxidant agents.