Antibacterial activities of phytochemical constituents from the leaves of Coula edulis (Olacaceae) and In silico investigations of ursolic acid.

Abstract

From the leaves of Coula edulis, fourteen compounds were isolated and identified: D-mannitol (1), a mixture of β-sitosterol (2) and stigmasterol (3), α-amyrin (4), betulin (5), lupeol (6), lupenone (7), betulinic acid (8), taraxerol (9), 3β-(E)-coumaroyltaraxerol (10), 3β-(Z)-coumaroyltaraxerol (11), ursolic acid (12), stigmasterol 3-O-β-D-glucoside (13), and β-sitosterol 3-O-β-D-glucoside (14). These compounds were analysed through NMR spectroscopy (both 1D and 2D) and by comparing them to previously published data. Compounds 1, 4, 5, and 7-9 have been identified from this species for the first time. Antibacterial activity was assessed, with compound 12 displaying the best efficacy against Staphylococcus aureus (MIC: 15.6 μg/mL). Molecular docking of compound 12 led to twenty lead compounds, among which 12 F displayed the highest score (-10.1 kcal/mol). Most lead compounds showed better scores compared to Vancomycin (-8.8 kcal/mol). Biovia Discovery Studio analysis reveals lead compounds interacting with CASTp-predicted active pocket amino acids.