Synthesis, biological evaluation and in silico molecular modelling studies of chloro substituted bis-indole containing benzohydrazide analogues as potential anti-diabetic and anti-Alzheimer's agents

•Synthesis of new bis-indolylmethane analogues and fully characterized by various spectroscopic techniques.•Identification of a new class of α-glucosidase, α-amylase, acetylcholinesterase and butyrylcholinesterase activities.•Structure activity relationship was established to understand the contribution of different substituents.•In silico studies of most active compounds were performed to understand the binding interactions with enzyme. Fifteen bis-indolylmethane analogues were synthesized, characterized through NMR (1H, 13C) and high-resolution electron-impact mass spectrometry (HREI-MS), and tested against α-glucosidase, α-amylase, acetylcholinesterase, and butyrylcholinesterase inhibitory potentials. All analogues exhibited different inhibitory potentials, with IC50 values ranging between 7.5 ± 0.92 to 58.4 ± 0.07 μM (α-glucosidase), and 0.80 ± 0.05 to 15.30 ± 0.10 μM (α-amylase) as compared to the standard drug acarbose (IC50 = 38.45 ± 0.80 and 8.90 ± 0.10 μM). Out of fifteen analogues, nine showed an excellent inhibitory potency that was manyfold better than standard drugs. A slight increase or decrease in inhibition was observed due to substituents attached at imine site. In the case of α-amylase inhibition, two analogues such as 2 and 11, showed excellent inhibitory potential with IC50 values of 0.80 ± 0.05 and 0.90 ± 0.10 μM while all other analogues showed good potency. All analogues were also tested against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory potentials, and they showed good potentials ranging from 1.40 ± 0.20 to 16.20 ± 0.50 μM (AChE) and 3.20 ± 0.10 to 19.60 ± 0.20 μM (BuChE) as compared to the standard drug Donepezil (IC50 = 2.16 ± 0.12 μM and 4.5 ± 0.11 μM). In the case of AChE, analogue 3 is the most potent, and in the case of BuChE, analogue 9 is the most potent among the series. The structure-activity relationship was carried out, mainly associated with the nature, number, and position and the electron-donating and electron-withdrawing effects of the substituent(s) on the phenyl ring. The binding modes as well as binding free energy for α-glucosidase and α-amylase inhibitors were determined through docking studies. [Display omitted]