Synthesis and Carbonic Anhydrase Isoenzymes Inhibitory Effects of Brominated Diphenylmethanone and Its Derivatives

Known and novel derivatives including CO, Br, and OH (benzylic and phenolic), and the corresponding benzylic alcohols of (3,4-dimethoxyphenyl)(2,3,4-dimethoxyphenyl)methanone were synthesized, and their inhibitory effects on the carbonic anhydrase (CA) isoenzymes I and II were investigated. CAs are the metalloenzymes catalyzing the reversible hydration of carbon dioxide (CO2 ) to bicarbonate (HCO3 (-) ). The inhibitory effects of diphenylmethanone derivatives 5-18 were tested on human CA (hCA, EC 4.2.1.1) isoenzymes (hCA I and hCA II) and they inhibited both isoenzymes at micromolar levels. Compounds 5 and 10 were found to be the best inhibitors against both CA isoenzymes. According to our data, compound 10 was the best inhibitor for isoenzyme hCA I (IC50 = 3.48 µM, Ki = 2.19 µM) whereas compound 5 was found to be the best inhibitor for isoenzyme hCA II (IC50 = 1.33 µM, Ki = 2.09 µM). Probably, stable conformations of 5 and 10 are more convenient for interaction with CA isoenzymes than those of the other compounds.