From the roots of the plant Tephrosia aequilata Baker, five flavonoids were isolated of which, 3,4:8,9-dimethylenedioxypterocarpan is reported for the first time. Its structure and those of the already known flavonoids were established by physical and spectroscopic analysis. Application of 2D NMR techniques was useful for complete characterization of the new pterocarpan as well as the other known flavonoids.

The tea plant, Camellia sinensis (L.) O. Kuntze is an important crop in the agriculturally based economy of Kenya. Many diseases affect the tea plant but the most prevalent is armillaria root rot caused by the fungus Armillaria mellea. Compounds from the fermentation of Trichoderma species in different media were bioassayed against some selected gram-positive and gram-negative bacteria, fungi including Armillaria mellea, a yeast and a Mucor. Compounds obtained from T. harzianum, and T. longibrachiatum when cultured in various media were investigated individually for in-vitro antifungal and antibacterial activities by agar diffusion technique. Some of the compounds produced definite antifungal and antibacterial activities. 2-Phenylethanol (1) and tyrosol (2) obtained from T. harzianum are reported for the first time from Trichoderma species. The most active metabolite isolated from these strains was 6-n-pentyl-•pyrone (3), which showed the highest antifungal and antibacterial activity and completely inhibited the growth of Armillaria mellea fungus at a concentration of 200 ppm. Compound 4 (sorbicillin) exhibited moderate activity against the fungal test organisms.

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Antibacterial and phytochemical screening of methanolic, sequential extracts (hexane, dichloromethane, ethyl acetate and methanol) and alkaloid rich fractions of Tabernaemontana stapfiana Britten was carried out. The phytochemical screening showed the presence of alkaloids, flavonoids, coumarins, tannins and saponins that have been associated with antimicrobial activity. The stem and root bark methanolic extracts showed good activity against the bacterial strains used including the multiple drug resistant Staphylococcus aureus strain with minimum inhibitory concentrations ranging from 15.6 to 500 µg/ml and minimum bactericidal concentrations ranging from 31.25 to 500 µg/ml. The sequential extracts of the root and stem bark had high antimicrobial activity with minimum inhibitory concentrations (MICs) ranging between 3.9 and 250 µg/ml and minimum bactericidal concentrations (MBCs) ranging between 7.8 and 500 µg/ml against the tested microorganisms. The dichloromethane extract of the alkaloid rich fractions however exhibited reduced antibacterial activities as compared to methanol and sequential extracts but the dichloromethane:methanol (4:1) mixture showed high activity with MICs ranging between 15.6 and 250 µg/ml. These antibacterial efficacy studies suggest that Tabernaemontana stapfiana Britten could be a source of antibacterial agents.