Sulfamates of methyl triterpenoates are effective and competitive inhibitors of carbonic anhydrase II

•Sulfamates of methyl triterpenoates were synthesized.•Several compounds were inhibitors for carbonic anhydrase II.•They act as competitive enzyme inhibitors even in a low μmol concentration.•Small changes in constitution cause tremendous effects in their activity.

Carbonic anhydrase II, belonging to one of the most important enzyme groups of the human body, is a well-studied isozyme from the family of the carbonic anhydrases. Since it is involved in several physiological processes, it has been a pharmaceutical target for many years. In this study we synthesized a number of sulfamates derived from pentacyclic methyl triterpenoates, and we demonstrate their potential as carbonic anhydrase II inhibitors using the well-established photometric 4-nitrophenyl acetate assay. Inhibition constants, as an indicator of their inhibition strength, were in the micromolar range; one compound (10, methyl (3β) 3-(aminosulfonyloxy)-oleanoate) showed a Ki value as low as 0.3 μM. This Ki value is comparable to that of acetazolamide which is a potent carbonic anhydrase inhibitor and a drug for the treatment of glaucoma.

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