Novel hydroxy- and amidino-substituted benzimidazoles and benzothiazoles as antibacterial and antiproliferative agents.

The aim was synthesis of novel benzazoles bearing amidino and 2-hydroxyphenyl substituents to explore their biological activity. Condensation of 5-substituted salicylaldehydes and intermediates gave new benzazoles by previously published and developed procedures, which were tested for antibacterial and antiproliferative activity . The best antibacterial activity showed benzimidazole with 2-imidazolinyl group and benzothiazole with an unsubstituted amidine (minimum inhibitory concentration 8 μg/ml). Benzothiazole proved most potent at inhibiting proliferation of all cancer cells (IC: 1.2-2.0 μM). Most active compounds have been recognized as lead compounds for additional optimization to improve their biological activity. The type of amidine moiety markedly influenced the biological activity. Benzothiazoles showed improved antiproliferative activity in comparison to benzimidazoles.