Written records about medicinal plants date back at least 5,000 years to the Sumerians. The objected plants for present investigation were indigenous to South Africa and as explored, only a few biological studies were found on the previous studies on Hyaenanche globosa and Maytenus procumbens. Phytochemical studies of the ethanol extract of the fruits of H. g/obosa (F.E) resulted in isolation of two known pure sesquiterpene lactones; 'tutin 1' and 'hyenanchin 2'. The crude extract and its isolated constituents were tested on four cancerous and a normal cell lines. F.E exhibited the highest antiproliferative activity on Hela cells which followed by Caco-2 cells. None of the isolated compounds were found to be toxic to the cells tested in this experiment. F.E demonstrated potent inhibition of DPPH radical activity similar to vitamin C. 'Tutin 1' and 'hyenanchin 2' were found with marginal antioxidant activity of which 'compound 1' presented more potent activity than 'compound 2'. The amounts of ROS radicals formed by pure compounds (1 and 2) were not significantly higher than those of controls. This is the first report on phytochemical index, anticancer, antioxidant and antibacterial properties of F.E and its purified compounds. The possible biochemical activities of the acetonic/ethanolic extract of the leaves of Maytenus procumbens (L.M.P), and its isolated compounds were investigated in the present study. L.M.P showed IC50 values of 68.79, 51.22, 78.49, 76.59 and 76.64 ì/ml on Caco-2, Hela, HT29, NIH3T3 and T47D cells by use of MTT cytotoxicity assay. Bioassay guided fractionation led to the isolation and identification of two new triterpenes: '30-hydroxy-11á-hydroxy-18â-olean-12-en-3-one 3' and '30-hydroxy-11á-methoxy- 18â-olean-12-en-3-one 5'. In addition, a known terpenoid: 'asiatic acid 4' was purified. Due to the unavailability of sufficient amount of 'asiatic acid 4', this compound was not tested. Pure compounds 3 and 5 exhibited the most cytotoxicity against Hela cells and were further investigated for their abilities for induction of apoptosis (at the concentration of their IC sub>50) in Hela cells using flow cytometric method. Both compounds induced apoptosis up to 73.20%, (compound 3) and 20.40% (compound 5) in Hela cells versus control group (0.40%). Antioxidant/oxidative properties of L.M.P and its isolated compounds were investigated using extracellular (DPPH), and intracellular reactive oxygen species (ROS) assays. L.M.P and the isolated compounds exhibited marginal DPPH discoloration. Experimental samples represented a time and concentrationdependent function of ROS formation in Hela cells. ROS generation might be a part of the mechanisms by which compounds 3 and 5 induced apoptosis in Hela cells. It can therefore be concluded that the active components in L.M.P might serve as a mediator of the reactive oxygen scavenging system and have the potential to act as a prooxidant and an antioxidant, depending on the biological environment of the cells. There is no report until date on phytochemical index, anticancer, antioxidant and antibacterial properties of L.M.P and its isolated compounds. / Thesis (PhD)--University of Pretoria, 2012. / Plant Science / unrestricted