Inhibition of MAO by substituted tryptamine analogues

Three different acetylenic analogues of tryptamine, in which the side chain is attached at the 2 position of the heterocyclic ring, were studied as inhibitors of MAO-A and MAO-B. IC50 values were determined after 30 min preincubation of the enzyme and inhibitor, at 37 degrees C before assay. Irreversibility and time-dependence of the inhibition were also established in each case. The kinetic parameters defining non-covalent complex formation and covalent adduct formation were calculated for the mechanism-based inhibition of both MAO-A and MAO-B by these compounds.