Chemical constituents, antitrypanosomal, antiplasmodial and antimicrobial activities of extracts from selected diospyros, millettia and annonaceae species.

This thesis reports on phytochemical investigations of methanol extracts of root bark, leaves and stem bark from 13 Tanzanian plant species selected for the study from the genera Diospyros and Millettia as well as from the family Annonaceae. The antitrypanosomal assay of methanol extracts carried out against Trypanosoma brucei brucei exhibited activities with IC50 values ranging from 1.28-7.85 g/mL. The antiplasmodial assay of methanol extract carried out against Plasmodium falciparum showed activities with IC50 values ranging from 4.55-24.22 g/mL. The antimicrobial assay of methanol extracts tested against Staphylococcus aureus, Bacillus cereus and Escherichia coli, exhibited activities with MIC values ranging from 1.25–6.25 g/mL (more active), 125–500 g/mL (moderately active), 1000–8000 g/mL (less active) and some were inactive at 16000 g/mL. The stem bark extract of Diospyros natalensis yielded two lignans namely 4-O-methylcedrusin and (-)-syringaresinol. The stem bark extract of D. squarrosa gave three compounds including methyl 2,4-dihydroxy-3,6-dimethylbenzoate, lupeol and sitostenone. The root bark methanol extract of Millettia sacleuxii yielded two pterocarpans namely (-)-medicarpin and (-)-maackiain along with 4′,7-dimethoxyisoflavone. The root bark methanol extract of Uvaria tanzaniae yielded two dihydrochalcones namely uvaretin and diuvaretin. The stem bark methanol extract of Monodora minor yielded a new indole (E)-4-(1H-indol-5-yl)-but-3-en-2-one along with sitosterol and 5-formyl-1H-indole. Uvaretin showed promising activity against Plasmodium falciparum with IC50 value of 7.20  and other compounds were inactive at 20 M concentrationExtracts which showed good activity are potential for future research.