Anticholinesterase, antioxidant potentials, and molecular docking studies of isolated bioactive compounds from Grewia optiva

Grewia optiva Drummond ex Burret (Tiliceae) is extensively applied for the treatment of typhoid, diarrhea, malaria, etc., in traditional medication. In this study, four bioactive compounds I (beta- sitosterol), II (1, 2, 3 benzene triol), III (7-O-methyl cathachin) and VI (betulinic acid) were isolated from the root of G. optiva. The compounds were characterized through UV, FTIR, NMR, and mass spectroscopic techniques. The isolated compounds were tested for the inhibition of synthetic-free radicals: ABTS and DPPH, and anticholinesterases: AChE and BChE. Compound III demonstrated highest percent free radicals scavenging activities against DPPH and ABTS (86.11 +/- 2.20, 85.23 +/- 1.61, respectively, for 1000 mu g/ml concentrations) with IC50 of 63 mu g/ml which were comparable to the IC50 value (35 mu g/ml) of ascorbic acid. All isolated compounds also showed excellent inhibitory potential against AChE and BChE. However, beta-sitosterol amongst them exhibited highest percent inhibition (87.66 +/- 1.93, 85.71 +/- 1.17, respectively, at 1000 mu g/ml concentration) with IC50 of 62 mu g/ml, which was close to the standard galanthamine IC50 values (40 mu g/ml). To support the findings of the study silico docking model was applied that predicted possible binding modes of beta-sitosterol with AChE and BChE. The para hydroxyl group of the phenolic moiety interacted with the active site water molecule and the side chain carbonyl residues through H-bonding. The remaining part of the active compound packed in a shallow pocket through H-bond.