Compound 3b was found to be most active inhibitor against membrane bound cytosolic hCAI and II isoform having KI values of 368.7 and 81.4 nM respectively while as 3n was found to be more effective against the tumour-associated hCA IX and XII isoforms having Ki value of 41.3 and 39.1 nM respectively. This evidence concerns the gene CYP24A1 and neoplasm.