Xysmalobium undulatum (Uzara) is one of the most widely used indigenous traditional herbal remedies in Southern Africa. Commercially available Uzara plant material was used to prepare a crude aqueous extract, of which the toxicity potential was investigated in the hepatic HepG2/C3A cell line in both traditional two-dimensional (2D) and rotating three-dimensional (3D) spheroid cell cultures. These cultures were treated over a period of 4 days at concentrations of 200, 350, 500, and 750 mg/kg plant extract to protein content. Basic physiological parameters of the cell cultures were measured during exposure, including cell proliferation, glucose uptake, intracellular adenosine triphosphate levels, and adenylate kinase release. The results indicated that all physiological parameters monitored were affected in a dose dependent manner, with the highest concentration of Uzara crude water extract (750 mg/kg) resulting in toxicity. Anti-proliferating effects of Uzara crude water extract were observed in both the 2D and 3D cell cultures, with the most pronounced effects at concentrations of 350, 500, and 750 mg/kg. Discrepancies between results obtained from the 2D and 3D cell culture models may be attributed to the type of repair system that is initiated upon exposure, depending on where cells are within the cell cycle. DNA repair systems differ in cells within the G1 phase and non-diving cells, (i.e. cells found predominantly in in vitro 3D and the in vivo situation).
Keywords: C3A; Uzara; Uzarin; cell culturing; hepatotoxicity; herbal medicine; spheroid; three-dimensional cell culture.