Cytotoxicity of antimalarial plant extracts from Kenyan biodiversity to the brine shrimp, Artemia salina L. (Artemiidae)

Artemia salina (Artemiidae), the brine shrimp larva, is an invertebrate used in the alternative test to determine toxicity of chemicals and natural products. In this study the medium lethal concentration fifty (LC50 values) of 45 antimalarial plant extracts and positive controls, cyclophosphamide and etoposide were determined using Artemia salina (Artemiidae). Out of the 45 organic extracts screened for activity against Artemia salina larvae, 23 (51%) of the crude extracts demonstrated activity at or below 100 μg/mL, and were categorized as having strong cytotoxic activity, 18 (40%) of the crude extracts had LC50 values between 100 μg/mL and 500 μg/mL, and were categorized as having moderate cytotoxicity, 2 (4.5%) of the crude extracts had LC50 values between 500 μg/mL and 1000 μg/mL, and were considered to have weak cytotoxic activity, while 2 (4.5%) of the crude extracts had LC50 values greater than 1000 μg/mL and were considered to be non toxic. Approximately 20% (9) of the aqueous extracts demonstrated activity at or below 100 g/mL and were considered to have strong cytotoxic activity, 40% (18) of the screened aqueous crude extracts had LC50 values between 100 μg/mL and 500 μg/mL and were considered to be moderately cytotoxic, 16% (7) of the crude extracts had LC50 values between 500 μg/mL and 1000 μg/mL and were considered to have weak cytotoxic activity while 24% (11) of the aqueous extracts had LC50 values greater than 1000μg/mL and were categorized as non toxic The positive controls, cyclophosphamide and etoposide exhibited strong cytotoxicity with LC50 values of 95 μg/mL and 6 μg/mL respectively in a 24 hour lethality study, validating their use as anticancer agents. In the current study, 95.5% of all the screened organic extracts and 76% of the investigated aqueous extracts demonstrated LC50 values <1000 g/mL, indicating that these plants could not make safe anti-malarial treatments. This calls for dose adjustment amongst the community using the plant extracts for the treatment of malaria and chemical investigation for isolation of bioactive compounds responsible for the observed toxicity.