Browsing by Author "Sempombe, Joseph"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Antimicrobial and other natural Benzenoids from three Tanzanian medicinal plants
    (University of Dar es Salaam, 2002) Sempombe, Joseph
    This Thesis reports on phytochemical investigations of three Tanzanian medicinal plants, namely Securidaca longepedunculata Fresen belonging to the family Polygalaceae, and Fadogia triphylla Baker and Catunaregum spinosa Thunb, both belonging to the family Rubiaceae. The dichloromethane extract of the root bark of S. longepedunculata yielded three benzenoids and one xanthone, all of which were identified on the basis of their spectral properties. These are benzyl 2-hydroxy-6 methoxybenzoate, methyl 2-hydroxy-6-methoxybenzoate, (4-methoxybenzo [1, 3] dioxo-5-yl)-phenylmethanone and hydroxy-4-menthoxyxantone. These compounds were not isolated from this plant in the previous investigations. Benzyl 2-hydroxy-6 methoxybenzoate exhibited anti bacterial activity against Pseudomonas aeruginosa, with an MIC value of 125 µg/ml, while 1,7-dihydroxy-4-methoxy xanthone exhibited anti bacterial activity against Staphylococcus aureus, with an MIC value of 125 µg/ml and anti fungal activity against Aspergillus niger, A. fumigatus and Penicillium species with zones of inhibition ranging from 15 to 20 mm. Phytochemical investigations of the ethanol extract of the roots of F. triphyla yielded two coumarins, namely scopoletin and a dimeric cinnamic acid derivative and an alditol, D-mannitol. Only the dimeric cinnamaldehyde derivative exhibited anti bacterial activity against Pseudomonas aeruginosa in vitro, having an MIC value of 125 µg/ml. Scopoletin which was earlier isolated from Micromelum integerrimum had an antitumor activity. In the literature no previous phytochemical investigations are reported on F. triphylla. Phytochemical investigations of the ethanol extract of the roots of Catunaregum spinosa yielded a scopoletin glycoside which did not show any activity against the tested organisms.