Phytochemical and antimicrobial studies of Olax viridis OLIV. (Fam: Olacaceae Juss) fruit

Abstract

Various anatomical segments of Olax viridis Oliv. are used in ethnomedicine for the management of wound ulcers, diarrhea, venereal disease, craw-craw, ring worm and typhoid fever. Thus, the antimicrobial activities of Olax viridis Oliv. fruit was investigated. Fresh fruits of O. viridis were harvested, dried and pulverized to a coarse powder. A 1-kg portion of the pulverized crude drug was defatted using n-hexane (F₁) and subsequently extracted with methanol in soxhlet, and the methanol extract (F₂) fractionated into F₃-F₈. All the fractions were screened for activity against some clinical strains of bacteria and fungi. Their phytochemical composition was, equally, determined using the methods described by Harbone. Fractions F₄, F₅, F₇ and F₈ showed very high activity against Staphylococcus aureus, Escherichia coli and Salmonella typhimurium with minimum inhibitory concentration (MIC) values of 12.5 – 25.0 mg/ml. This compared favourably (p < 0.05), to those of ampicillin and chloramphenicol (0.125–0.500 mg/ml). Fractions F₃ and F₆ also showed pronounced, but slightly lower, antimicrobial activity with MIC value of 12.5 mg/ml. All the fractions lacked activity against the fungal species: Aspergillus niger and Candida albicans. Generally, S. aureus was most sensitive to the test drugs, while E. coli and S. typhi were more or less equi-sensitive. Fractions F₄ and F₇ consisted mainly of alkaloids while F₃ and F₆ were contained triterpenes and volatile oils. Flavonoids were the major constituents of F₅ and F₈. Taken together, the antibacterial activity of Olax viridis may be attributed to triterpenes, alkaloids and flavonoids. Our study underscores the scientific bases of some of the uses of Olax viridis Oliv. in traditional medicine.