Monoamine oxidases (MAOs) are mitochondrial bound enzymes, which catalyze the oxidative deamination of monoamine neurotransmitters. Inside the brain, MAOs are present in two isoforms: MAO-A and MAO-B. The activity of MAO-B is generally higher in patients affected by neurodegenerative diseases like Alzheimer's and Parkinson's[2]. Kava-kava, a psychoactive beverage, induces relaxation, improves social interaction, promotes sleep and plays an important role in the sociocultural life in the islands of the South Pacific. Kava pyrones, the major constituents of kava kava, are generally considered to be responsible for the pharmacological activity in humans and animals. Desmethoxyyangonin, one of the six major kava pyrones found in the Piper methysticum (kava-kava) plant, is a reversible inhibitor of MAO-B. As the most potent kava pyrone, desmethoxyyangonin displays a competetive inhibition pattern with mean Ki 0.28 µM[3]. A small dose of kava extract (20 mg/kg body weight i.p.) caused changes in rat behaviour and concentrations of dopamine in the nucleus accumbens. Higher doses (120 mg/kg i.p.) increased the levels of dopamine[4]. Among the kava pyrones, only desmethoxyyangonin markedly induced the expression of CYP3A23[5].
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