On the basis of pharmacophoric modelling studies of existing NNRTIs, a series of isatin β- thiosemicarbazone derivatives was synthesized and evaluated for their anti-HIV activity in HTLV-IIIB strain in the CEM cell line. Three compounds showed significant anti-HIV activity, whereupon compound 6 was found to be the most active compound with an EC50 value of 2.62 μM and a selectivity index of 17.41, while not being cytotoxic to the cell line at a ...