An in vitro study of South African Ziziphus’ antiplasmodial and antigonococcal bioactivity

For centuries, Ziziphus species have been used in African traditional medicine as remedies for human ailments. In this study, South Africa’s indigenous Ziziphus species ( Z. mucronata , Z. rivularis, and Z. zeyheriana ) are evaluated for their antiplasmodial and antigonococcal phytoconstituents. The plant parts were air-dried, and sequentially extracted using n -hexane, dichloromethane, ethyl acetate, ethyl acetate:methanol (1:1), and methanol. Forty-eight extracts were obtained and subjected to antiplasmodial and anti-gonococcal bioassays. Further NMR-based metabolomics to predict bioactivity in unknown samples and identify active phytoconstituent classes was conducted. The PCA and OPLS-DA analysis was applied to reduce dimensionality and contribution plots were generated to observe discrimination according to observed bioactivity. Of the 48 assayed extracts, 31 and 54% were inactive against malaria and gonorrhea, respectively. For malaria, 13 and 23% corresponded to high and moderate activity respectively. For gonorrhea, 12.5 and 33.3% corresponded to extracts with high and moderate activity, respectively. Ziziphus rivularis leaves recorded the highest antigonococcal activity (MIC