In-vitro Cytotoxicity of Extracts of Selected Malaria Medicinal Plants Used by Traditional Healers of Kericho East Sub-county, Kenya

Background: Malaria is a fatal disease which affects people of all ages; especially pregnant women, young children <5 years, and the elderly because of their weakened immune systems. The currently used anti-malarial drugs have been linked to a variety of negative side effects including the parasite resistance. Additionally, the costs associated with the conventional malaria management approach are arguably high, particularly for people living in low-income countries, highlighting the need for alternative and complementary approaches. Medicinal plants therefore are a viable alternative since they are arguably less expensive and easily accessible. However, there is limited information on safety and efficacy of the plants. This study was designed to investigate the cytotoxic activities of polar and non-polar crude extracts solvents of selected plants used by traditional healers in Kericho East Sub-County to treat malaria.

Materials and Methods: Plants studied included Pittosporum viridiflorum (stem barks), Phytolacca dodecandra (Leaves), and Gardenia ternifolia (roots barks). Plant parts selected were collected from Kericho East Sub-county; Kapsoit, Kaitui, and Fort-Ternan. Their crude extracts were obtained from hexane, dichloromethane (DCM), Methanol (MeOH), and 5% H2O/MeOH. In vitro cytotoxic effects and safety of the studied plants' extracts were identified using mammalian Vero E6 cells.

Results: Most of the plants tested yielded impressive cytotoxicity results, indicating that therapeutic doses could be achieved at safe concentrations. However, P. viridiflorum hexane, DCM, MeOH, and 5% H2O/MeOH crude extracts were toxic to the cultured cells expressing the mean CC50 ± SE of 65.11±0.40, 25.63±0.23, 87.94 ±0.59 and 98.54±0.66 μg/ml, respectively.

Conclusion: G. ternifolia and P. dodecandra have offered hope in the treatment of malaria since their crude extracts have demonstrated no toxicity. The study found P. viridiflorum crude extracts to be toxic but there is the possibility of isolating safe nontoxic compound/s because they were less toxic at lower doses. This study therefore identified potential plants that could be used to develop novel anti-plasmodial agents.