Biflavonoids from an Ethno-Medicinal Plant Ochna holtzii Gilg
Ochna holtzii Gilg is a medicinal plant used extensively at the Kenya Coast for the treatment of various ailments. From solvent extracts of the root and stem barks of O. holtzii, seven constituents were isolated by standard chromatographic techniques (CC, VLC, prep-TLC and Sephadex LH-20). Their structures were analyzed by MS, UV,IR,1D and 2D NMR spectroscopy. All were found to be biflavonoids, including three novel compounds: dehydrate of lophirone C, hotzinol, and tri-O-methyl lophirone A. Crude methanol extracts of O. holtzii and the isolated biflavonoids were tested for antimicrobial activities against two Gram-positive bacteria, Staphylococcus aureus and Bacillus subtilis, two Gram-negative bacteria, Salmonella typhi and Pseudomonas aeruginosa, and the diploid fungus Candida albicans. The extracts and the isolated constituents showed varying levels of activities against the microbes. Afzelone D, lophirone A and the novel tri-O-methyl lophirone A showed strong activities against P. aeruginosa and S. aureus, with the latter being more susceptible. Calodenin B and the novel dehydrolophirone C also showed strong activities against these bacteria, but were more active against P. aeruginosa. However, none of these matched those of the antibiotic Chloramphenicol or the antifungal Fluconazole. This represents the first study on phytochemical and antimicrobial profiles of O. holtzii.