Phytochemical investigation of secondary metabolites from monanthotaxis discolor, diesiothamnus divaricatus and an undescribed unvariodendron Sp

This thesis reports the results on isolation of secondary metabolites and biological activities of both crude extracts and compounds from three Annonaceae plant species namely; Monanthotaxis discolor, Dielsiothamnus divaricatus and an undescribed Umriodendron sp. Six compounds were isolated from dichloromethane extracts of Al. discolor root bark and one from ethanol:dichloromethane (1:1 v/v) leaves extract. These include the known compounds karatavin (2.18), N-acetylanonaine (2.19), stigmasterol (1.14) and the mixture of stigmasterol (1.14) and 13-sitosterol (1.15) and Octahydro-5-isopropyl-3-methyl-2-methyleneazulene-8,8-diol (2.26). A new compound, 3,6, 13-trimethyl- 1 0-o xa-bicyclo [7 .2 .2] trifecta- 1 ,3 ,6-triene-5 ,8, 1 1 -trione (2.25) was also isolated. Ethanol-dichloromethane extract of M. discolor leaves yielded Quercetin-3-0-arabinose (2.23). The dichloromethane extract of Dielsiothamnus divaricatus stem wood yielded uncommon fatty amide Hexadec-8- enoic acid butylamide (2.24), whereas both ethanol and dichloromethane extracts of Uvariodendron sp. root bark yielded fatty acids 9- octadecen-12-ynoic acid (2.27) and heptacosanoic acid (2.28). The methanol and dichloromethane crude extracts of Al discolor root bark exhibited high cytotoxic activity of LC50 13.56 and 41.79 tig/mL, respectively. The extracts exhibited varying in vitro antimicrobial activities, whereby the dichloromethane extract showed IZ 8.0 mm, Al 0.33 for Escherichia coli and 5.0 mm, AI 0.21 for Streptococcus aureus whereas the methanol extract showed only activity to Streptococcus aureus at mean inhibition zone of 5.0 mm. Compound 2.25 exhibited cytotoxicity activity of LC50 5.88 1,1g/mL and antifungal activity against Candicla albicans (IZ 7.0 mm, AI 0.44, MIC 0.13 mg/mL) and Aspergillus niger (IZ 5.5 mm, AI 0.31, M1C 0.17 mg/mL). Compound 2.23 exhibited