Assessment of cytotoxicity of leaf extracts of Andrographis paniculata and Aspilia africana on murine cells in vitro.

People, especially in rural environments and recently, those dissatisfied with conventional medicine use medicinal plants for their therapeutic effects. Two or more plants are usually combined for such use and these combinations cause interactions that may be safe but could also be detrimental to health. Used singly, Andrographis paniculata and Aspilia africana are considered safe plants with low toxicities but little is known about their safety in combined therapy. This study assessed the cytotoxic activities of the aqueous, methanol and chloroform extracts of the two plants in a 1:1 combination at various concentrations on murine hepatocytes, thymocytes and splenocytes. The murine cells were seeded in microtitre plates and tested with the combined extracts at different concentrations and percentage viability values of the cells determined by the tetrazolium salt reduction assay (MTT). The extracts used were: combined aqueous extract of the two plants (CAE), and combined chloroform extract (CCE). At 72hr incubation with 500 μg/ml extract concentration, percentage viability was low. Splenocytes thymocytes and hepatocytes incubated with CAE had viability values of 35%, 28% and 64% respectively and with CCE, 26%, 26% and 36% respectively, relative to controls. From the results, the extracts were cytotoxic to the murine cells at this concentration and incubation period. These low values indicate cytotoxic interactions in the combined extracts. However more research is needed to understand the mechanisms of cytotoxicity of the plants.