Novel diterpenoids, a trimeric epoxybinaphthoquinone and other constituents of some bioactive plants from Tanzania

This Thesis reports on screening of some plants belonging to nine different families in the Brine Shrimp Lethality Test (BST). The plants are either used traditionally for pest control and medicinal purposes or belong to families known to be potential sources of insecticidal or antimicrobial compounds. The majority of the less polar extracts demonstrated the high activity. Phytochemical investigations were earned out on three plant species of the family Linaceae, Ebenaceae and Annonaceae, namely Hugonia castaneifolia, Diospvros mafiensis and Uvaria acuminata, respectively. The pet ether and dichloromethane extracts of the root barks of H. castaneifolia yielded the hydroxyrosane diterpenoid hugorosenol, the previously known bis nor-pimaranoid hugonone B and the new dinor-pimaranoid castaneinone. The pet ether extract of the root barks of D. mafiensis yielded the triterpene lupeol, the sesquiterpene 10-aromadendranol, the 1, 4-naphthaquinone 7-methyljuglone and the novel trimenc epoxybinaphthoquinone. The fungicidal activity of the crude extracts of D. mafiensis was higher than that recorded for bactericidal activity, mafiequinone being one of the active principles. The dichloromethane extract of the root barks of U. acuminata yielded C-benzylated dihydrochalcones uvaretin and diuvaretin as a mixture, chamuvaritin, a mixture of triuvaretin and isotnuvaretin and a mixture of angoluvarin, diuvaretin and triuvaretin. In the BST and antimicrobial tests, the crude extract, VLC fractions and the isolated compounds of the root barks of U. acuminata showed significantly high activities.