Constituents of Momordica foetida and Evaluation of their Antimicrobial Activity

Plants are a potential source of antimicrobial compounds. In this research, a plant from the family Cucurbitaceae was studied. Momordica foetida Schumch. Et Thonn is a climber commonly found in swampy areas in Central and Southern Africa. It has medicinal uses ranging from spiritual and psychiatric conditions to physical diseases. Drinking of aqueous leaf extracts of the plant for the treatment of malaria is reported in East and Central Africa [1,2]. The leaves were extracted using 70% ethanol and partitioned into hexane, chloroform, ethyl acetate, butanol and aqueous then screened for antimicrobial activity against 32 bacterial strains for both standard and isolates. Thus, ethyl acetate and chloroform fractions were chosen for further studies due to higher antimicrobial activity with minimum inhibitory concentration (MIC) values for 32 bacterial strains ranging from 0.156 and 2.5 mg mL⁻¹. Active fractions were further purified using chromatographic techniques. A detailed phytochemical investigation resulted into isolation of four curcubitane triterpenoids and flavonoids compounds from chloroform and ethyl acetate fractions respectively. The chemical structures of the isolated compounds were established through UV, IR, MS, ¹H, ¹³C, COSY and 2D NMR spectroscopic data. Antimicrobial investigations were carried out on the isolated compounds against 25 bacterial strains of which 3β,7β-dihydroxyl-cucurbita-5,23,25-trien-19-al followed by Kaempferol-3-O-β-D-glucopyranoside displayed minimum inhibitory concentration (MIC) values for 25 bacterial strains ranging from 7.8 to 250 µg mL⁻¹. Acknowledgement: We are grateful to the National Research Foundation and University of Zululand, South Africa for financial support. References: [1] Hakizamungu E, et al. (1992) J Ethnopharmacology 36: 143–146. [2] Rwangabo PC, (1993) La medicine traditionnelle au Rwanda. Edition Karthala and ACCT, Paris, France.