Plants take bite out of deadly snake venoms

From New Orleans, at a meeting of the Society of Toxicology

In many warm parts of the world where agriculture remains largely nonmechanized, farmers face the deadly risk of snakebites as they tend their fields. Therapeutic antivenins can be costly—and they require refrigeration, which isn’t reliably available in the developing world. A Nigerian pharmacologist has found in local plants a potentially cheap and easy-to-store antidote to all these problems.

Isaac U. Asuzu of the University of Nigeria Nsukka in Enugu and his colleagues consulted native healers about plant concoctions they prescribed for snakebites. The scientists then ran extracts from the plants through test-tube assays for activity against venoms of the Nigerian spitting cobra (Naja naja nigricollis), puff adder (Bitis arietans), and saw-scaled viper (Echis ocellatus).

Products from five plants showed promise. They included bark of the Parkia biglobosa tree and parts of four shrubs whose names Asuzu is withholding as part of an agreement with the suppliers of those plants. When combined, the seven active chemicals identified in the plants performed well in standard antivenin tests, Asuzu reported.

For instance, a tiny quantity of the concoction prevented the viper’s hemorrhage-inducing venom from killing chick embryos. Similarly, all three venoms killed mouse skeletal-muscle cells unless the plant antidote was present. In other tests, cobra venom that normally causes paralyzing, sustained contractions of chick-muscle tissue triggered only negligible contractions in the presence of the plant extracts.

Because the plant combo proved active against so broad a range of poison types, Asuzu says, “I presume it would be effective for other venoms,” such as those from kraits and rattlesnakes. His team is now looking for international collaborators to begin testing the multicomponent antivenin in lab animals.

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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