Toxicity Testing of Two Medicinal Plants, Bridelia micrantha and Antidesma venosum

A. venosum and B. micrantha are widely used ethnomedically and B. micrantha has furthermore indicated the potential to be developed into a drug due to the various biological activities previously reported. However, the safety of a plant must be determined before drug development. Cytotoxicity was determined using human adenocarcinoma cells of the cervix (HeLa), human breast cells (MCF-12A), lymphocytes (both resting and stimulated) as well as primary porcine hepatocytes. Acute systemic toxicity was determined using the luminescent bacteria, Vibrio fischerii and the vertebrate, Poecilia reticulata (guppy). Toxicity was found to be concentration dependent when HeLa and MCF-12A cells were exposed to the plant extracts. The IC50 was not reached at the concentrations tested (0.1 μg/ml – 1 mg/ml) for the hepatocytes as well as the resting and stimulated lymphocytes, indicative that both plant extracts showed little or no direct cytotoxicity against primary cultures. Both extracts resulted in 100% mortality of the guppies. This study illustrated that extracts of both B. micrantha and A. venosum are cytotoxic and possess acute systemic toxicity.