Аннотация:Human genome has more than 60 genes coding for FAD- and NAD(P)-dependent monooxygenases, among those monoamine oxidase B (MAO B) from mitochondria and catalytic domain of MICAL are most known. Benzimidazoles represent the drugs widely used to treat intestinal parasites. Albendazole was shown to inhibit MAO B. Four benzimidazoles were tested with the well-characterized and commercially available bacterial para-hydroxybenzoate hydroxylase (PHBH), which belongs to the same group of FAD-monooxygenases and can serve as a representative enzyme. PHBH was shown to be competitively inhibited by all four benzimidazoles (mebendazole, albendazole, fenbendazole, oxibendazole) in the millimolar range in the hydroxylase reaction, but not in non-physiological NADPH-dehydrogenase reaction of ferricyanide reduction. Hydroxylase reaction proceeds via formation of a ternary complex, whereas NADPH_dehydrogenase reaction follows a ping-pong mechanism. Thus, benzimidazoles compete with the transient form of the enzyme formed upon binding of a specific substrate. One may expect that benzimidazole drugs in human actually target a whole spectrum of FAD-monooxygenases. On the other hand, banzimidazoles are known pharmacophores and can be used as a starting point to develop inhibitors specific for each FAD-monooxygenase of interest.