Anticonvulsant and antimicrobial constituents from diospyros mafiensis and a novel phenylpropanoyl diterpene from isolanacauliflora

This thesis reports on the isolation and structural determination of natural products from the plant species Heteromorpha trifoliara (Apiaceae),isilana cauliflora (Annonaceae) and Diospyros mafiensis (Ebenaceae). The epoxy-dinaphthoquinone diosquinone was isolated from D. mafiensis as a mixture of two conformationalisomers (rotamers) and also being mixed with its positional isomer, and the triterpene lupeol. While the crude D. mafiensis extracts exhibited significant cytotoxicity (BST), antibacterial, antifungal and anticonvulsant activities, diosquinone was active against several bacteria strains, the activity being greatly enhanced in a mixture of diosquinone and its positional isomer. H. trifoliate, a plant which is used as a herbaremedy for various ailments, yielded small amounts of O-methoxyscopoletin and tetracosyl hexacosanoate, which could not be assayed for bioactivities due to paucity of the material. I. cauliflora yielded small amounts of the known prenylated indoles caulidine A {3-(1,1-dimethyl-allyl)-5-(3-methyl-but-2-enyl)- 1lH-indole), caulindole C (3,4-trans)-3-[3'-(1"'. 1"'-dimethyl-2"'-propenyl)-5'-indolylJ]-1,4-dim ethyl-4{2- [3"-(1"",1""-dimethyl-2""-propenyl)-5"-indolyl ]-ethyl-2-eny1}-cyclohex-l –ene}, polycarpol, a mixture of sterols and a new phenylpropanoy1 diterpene isolotrione (6- hydroxy-6,10,14,18-tetramethy-3-phenyl-nonadec- 17-en-2,5,16-trinone), which were also not assayed for bioactivities.