Phytochemical investigation of friuts of dovyalis abyssinica and evaluation of its antimicrobial activities

Abstract

Dovyalis abyssinica is a medicinal plant known in Ethiopia and some African countries for its edible fruit and use in traditional management of gonorrhea, brucellosis, tooth problems and mastitis in animals. The main objective of this study was to isolation and characterization of bioactive compounds from the fruits. The dried was subjected to extraction with petroleum ether, chloroform, acetone, and methanol sequentially by cold maceration method. The crude extracts obtained were then evaluated for antimicrobial activities on four bacterial strains (S. aureus, E. coli, P. aeruginosa and B.cereus ) and two fungal strains (Fusarium spp. and S. cerevisiae) using agar diffusion assay. The most activity guided then subjected to column chromatographic separation on silica gel using increasing gradient of petroleum ether in ethyl acetate. The isolated compounds were then characterized on the bases of observed spectroscopic data ( 1 H-NMR, 13 CNMR and DEPT-135) and comparison with literature. Extraction gave 11.99%, 3.5%, 2.43% & 1.67% for methanol, acetone, and chloroform and petroleum ether respectively. The extracts had a zone of inhibition 7.0-21.0 mm on tested strained. Fungal strains were more susceptible than bacteria and the chloroform extracts have shown the highest activity. Out of 254 fractions 76-89 and 108-140 gave pure compounds DA-1 (27.9 mg) and DA-2 (20.1 mg) respectively by washing with hexane and further purification on sephadex. The compounds were also characterized to be β-sitosterol and Catechol respectively. These compounds were not reported before from fruits of the study plant. Antimicrobial activity of Compound-2 (DA-2) was higher than Compound-1(DA-1). Thus, the observed antimicrobial activities of crude extracts and isolated compounds justify the traditional use of the plant for treatment of different microbial diseases.