Title : Flavonoids and other metabolites from the leaves of Garcinia smeathmannii, in vitro and in silico anti-inflammatory potentials
Abstract:
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-in?ammatory (ROS), antiglycation and antileishmanial (L. tropica) activities. Compounds were also screened for their in silico anti-in?ammatory 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 ?avonol [6,8-C-dimethylkaempferol 4′-acetate 3,7-dimethyl ether (1)] and a ?avone dimer [4′,7″-diacetylamento?avone (2)] together with eighteen known compounds sorted as three bi?avones [amento?avone (3), sequoia?avone (4)and, a mixture of sequoia?avone (4) and putra?avone (5)], one ceramide [citropremide (6)], two alkylphenols [eugenol, 1 acetate (7) and eugenol (8)], two benzoic acids [diisooctyl phthalate (9) and anhydride benzoic (10)], one gluco?avone [vitexin (11)], two xanthones [1,2,5-trihydroxyxanthone (12) and 1,3,6-trihydroxyxanthone (13)], one triterpène [D:Afriedoolean-6-ene (14)], two sterols [a mixture of stigmasterol (15) and β-sitosterol (17)], two sterol glucosides [a mixture of stigmasterol glucoside (16) and β-sitosterol glucoside (18)], and two fatty acids [dotriacontanoic acid or lacceric acid (19) and tritriacontanoic acid or psyllic acid (20)] were characterized. All the tested samples in vitro revealed no antiglycation and antileishmanial activities. Beside, extracts revealed moderate anti-in?ammatory activities (IC50 ranging from 24.1 ± 2.0 to 34.7 ± 0.8 μg/mL). Only compound (13) revealed an anti-in?ammatory activity which was 9.33 times more active than the reference (Ibuprofen, IC50 = 11.2 ± 1.9 μg/mL) with IC50 of 1.2 ± 0.0 μg/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 anti-in?ammatory 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.
