Two new flavonoids from the leaves of Garcinia smeathmannii, in vitro and in silico anti-inflammatory potentials

Garcinia smeathmannii is a well-known plant for its uses in the effective treatment of intestinal parasites, skin eruptions and skin burns. The dichloromethane-methanol (2:3) crude extract of the leaves of G. smeathmannii led to the isolation and characterization of twenty compounds (1-20) using chromatographic and spectroscopic techniques. Extracts and compounds were screened in vitro for their anti-inflammatory (ROS), antiglycation and antileishmanial (L. tropica) activities. Compounds were also screened for their in silico anti-inflammatory activities using Maestro 4.2.1 software with the co-crystal complex structures of the ovine oCOX-1: meloxicam (PDB Id: 4O1Z) and murine mCOX-2: meloxicam (PDB Id: 4M11) proteins. An unprecedented flavonol (1) and a flavone dimer (2) together with eighteen known compounds (3-20) were characterized. All the tested samples in vitro revealed no antiglycation and antileishmanial activities. Beside, extracts revealed moderate antiinflammatory activities (IC50 ranging from 24.1 f 2.0 to 34.7 f 0.8 mu g/mL). Only compound (13) revealed an anti-inflammatory activity which was 9.33 times more active than the reference (Ibuprofen, IC50 = 11.2 f 1.9 mu g/mL) with IC50 of 1.2 f 0.0 mu g/mL. Compounds (2-9, 11-13 and 19-20) were docked and the docking scores were ranging from-10.178 to-6.119 (kcal/mol) which were in agreement with the experimental antiinflammatory activity. These results are in agreement with the traditional uses of the leave of G. smeathmannii as cataplasm for skin eruption and as analgesic agent.