Kavain (Unlike papain, does not make you strong like Popeye)

Kavain is a member of a class of compounds known as the kavalactones. (A lactone is a cyclic ester; click here for examples).

Kavain is a species found in the kava plant, which is used by the aboriginal residents of some Pacific islands and has psychoactive activity. It's attracted use as a dietary supplement lately. It's also attracted some attention for possible toxicity, particularly to the liver.