Semicarbazide-sensitive amine oxidase kills African trypanosomes in vitro.

The African trypanosome Trypanosoma brucei is the cause of sleeping sickness in humans and Nagana in animals. Here we report that semicarbazide-sensitive amine oxidases (SSAOs), enzymes that are abound in T. brucei mammal hosts, eliminate trypanosomes by oxidation of its substrate in vitro. SSAO and its endogenous substrate methylamine are not toxic to T. brucei, but parasites were killed in the presence of both of them. SSAO inhibitors antagonized the SSAO-methylamine induced toxicity on T. brucei. The trypanocidal activity was mainly associated with formaldehyde generated in the SSAO mediated oxidation of methylamine. This finding suggests that SSAO may play some roles in non-specific defense of trypanosome infection in mammals.