Antimicrobial and cytotoxic activity of the stem and root bark extracts of Quassia undulata and isolated constituents

Abstract

The stem and root barks of Quassia undulata were exhaustively extracted with methanol to give the methanolic extracts: MeQuS and MeQuR, respectively. The chloroform extracts were obtained and fractionated on an open column of silica gel by gradient elution with chloroform and chloroform–methanol mixtures. Purification of fractions afforded the isolation of four compounds, namely: 3′-(8-hydroxy,6-methoxy,2-oxo-2H-1-benzopyran-7-yloxy)-3′,4′-dihydro, 7′-methoxy,2H-1-benzopyran (eniotorin) (1) a new bisbenzopyran coumarin, 7-hydroxy-6-methoxy-2H-1-benzopyran-2-one (scopoletin) (2) (a coumarin); glaucarubinone (3) and 15-desacetylundulatone (4) (quassinoids). The antimicrobial activities of the extracts and isolated compounds were evaluated against five microbes, namely: Staphylococcus aureus; Eschericha coli; Pseudomonas aeruginosa; Klebsiella pneumonia and Candida albicans. The extracts exhibited a broad-spectrum activity against the tested microbes. Cytotoxic activities of the extracts and compounds isolated from them were also examined against brine shrimps, Artemia salina. The extracts and the compounds showed significant dose-dependent activities.

Keywords:

• Quassia undulata
• antimicrobial
• cytotoxicity
• eniotorin
• scopoletin
• quassinoids