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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