Inhibition of mammalian carbonic anhydrase isoforms I, II and VI with thiamine and thiamine-like molecules

Here we determined the in vitro inhibitory effects of 5-(2-hydroxyethyl)-3,4-dimethylthiazolium iodide (1), 3-Benzyl-5-(2-hydroxyethyl)-4-methylthiazolium chloride (2) and thiamine (3) on human erythrocyte carbonic anhydrase I, II isozymes (hCA I and hCA II) and secreted isoenzyme CA VI. K I values ranged from 0.38 to 2.27 mu M for hCA I, 0.085 to 0.784 mu M for hCA II and 0.062 to 0.593 mu M for hCA VI, respectively. The compounds displayed relatively strong actions on hCA II, in the same range as the clinically used sulfonamidesethoxzolamide, zonisamide and acetazolamide.