Cannabis extract, but not delta 1-tetrahydrocannabinol, inhibits human brain and liver monoamine oxidase.

Mitochondrial monoamine oxidase (MAO) of human brain and liver was inhibited by low concentrations of cannabis extract (CE) and a cannabinoid fraction isolated from it. delta 1-Tetrahydrocannabinol (THC) did not elicit any inhibitory effect on the enzyme. The inhibition of MAO activity by CE and by its active fraction was more pronounced when the monoamine substrates 2-phenylethylamine (PEA) and benzylamine (BA) were used, as compared to the inhibition of the enzyme activity when 5-hydroxytryptamine was the substrate. The active cannabinoid fraction was found to be more potent than CE in inhibiting the activity of MAO with either substrate. The isolated fraction contains at least two cannabinoids with Rf values of 0.67 and 0.71 on silica gel thin layer chromatography (TLC), as determined with toluene/chloroform/methanol (100:10:1, by volume) as the solvent system. The findings of this study emphasize the need for further exploration of the potential of cannabis as a source for therapeutic agents.