Browsing by Author "Ngwira, Kennedy"

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    Phytochemical and biological studies of secondary metabolites from berberis holstii
    (The university of Dar es Salaam, 2012) Ngwira, Kennedy
    The dissertation reports on an evaluation of crude extracts, fractions and compounds from the leaves and roots of Berberis holstii on their antiplasmodial activities and HIV neutralizing activities in vitro. The antiplasmodial activities were evaluated against a chloroquine sensitive 3D7 strain of the malaria parasite, Plasmodium falciparum and the HIV activity against HBX2 and ZM53 pseudovirions. Parasite Lactate Dehydrogenase (pLDH) assay was used to measure parasite viability and Luciferase Reporter Gene assay was used for HIV neutralizing activity. The crude alkaloid extract from the roots showed the most potent anti parasitic activity (IC50 < 1 µg/mL) followed by dichloromethane/methanol extract (IC50 < 3 µg/mL). The bioactivity-guided fractionation resulted in isolation of berberine (IC50 = 1.844 µg/mL). An evaluation of the cytotoxicity of the compound showed a selectivity index (SI = CC50/IC50) value of 1.2. The crude aqueous extract from the leaves exhibited a good HIV neutralizing activity against the HXB2 virus (IC50 = 5.84 µg/mL) with improved activity than fusion inhibitor T20 drug (IC50 = 10.2 µg/mL). The DCM/MeOH extract from the leaves had an IC50 = 62.32 µg/mL. All other extracts were less active (IC50 > 100 µg/mL) against both HXB2 and ZM53 pseudovirions. Aqueous extracts and DCM/MeOH extract from the leaves were not toxic against TZM-bl cells (CC50 > 100 µg/mL) whilst all other extract were toxic only at the highest concentration of 100 µg/mL.