Synthesis, molecular modelling, in vitro and in vivo evaluation of conophylline inspired novel benzyloxy substituted indole glyoxylamides as potent pancreatic lipase inhibitors.

Pancreatic lipase is a digestive enzyme involved in the hydrolysis of dietary fats. Orlistat, a potent pancreatic lipase inhibitor, is widely prescribed for long-term obesity treatment. Nevertheless, orlistat is reported for severe adverse effects including hepatotoxicity and pancreatitis. In the present study, a novel series of 11 benzyloxy substituted indole glyoxylamides were designed, synthesized and evaluated for in vitro pancreatic lipase inhibitory activity. Three analogues, 10b, 11b and 11c, exhibited potent activity (IC50 ≤ 2.5 µM), with 11b exhibiting a potent IC50 of 1.68 µM comparable to orlistat (IC50 = 0.99 µM). Further, 11b exhibited reversible competitive inhibition with an inhibitory constant value of 0.98 µM. Molecular docking of these analogues was in agreement with in vitro results, wherein the MolDock scores exhibited significant correlation with their inhibitory activity (Pearson's r = 0.7122). A 50 ns molecular dynamics simulation of 11b-pancreatic lipase complex confirmed the role of extended alkyl interactions along with π-π stacking and π-cation interactions, in stabilizing the ligand (Maximum RMSD ≈ 3 Å) in the active site. Gastro-intestinal absorption and toxicity prediction of the three potent analogues highlighted the suitability of 11b for in vivo experiments. 11b at a dose of 20 mg/kg exhibited anti-obesity efficacy comparable to orlistat (10 mg/kg), wherein the serum triglycerides were found to be 94.95 and 83.85 mg/dL, respectively. Further, faecal triglyceride quantification indicated 11b to act through pancreatic lipase inhibition similar to orlistat. The present study identified a novel pancreatic lipase inhibitory benzyloxy substituted bis(indolyl) glyoxylamide 11b, with promising anti-obesity activity.Communicated by Ramaswamy H. Sarma.

Development and validation of a new HPTLC-HRMS method for the quantification of a potent pancreatic lipase inhibitory lead Echitamine from Alstonia scholaris.

Alstonia scholaris is an important indole alkaloid rich medicinal plant with diverse pharmacological activity. To understand the effect of extraction techniques, the stem bark sample of A. scholaris was subjected to continuous hot percolation, ultrasonic extraction, and cold maceration techniques. Continuous hot percolation technique extractive exhibited a potential pancreatic lipase (PL) inhibitory activity and further bio-assay guided fractionation resulted in the isolation of echitamine with a PL inhibitory activity (IC50 = 10.92 µM). A new validated HPTLC-HRMS method was developed for the quantification of echitamine by using a mobile phase of chloroform: methanol (80:20, v/v) with 0.04% formic acid. Echitamine content in the individual extractives were in direct correlation with the PL inhibitory activity (Pearson's r = -0.9409). The molecular docking studies further confirmed the PL inhibitory potential of echitamine. These results clearly highlight the role of echitamine as a natural product-based lead for potent PL inhibitory activity.