Synthesis and antiproliferative activity of new thiazole hybrids with [3.3.0]furofuranone or tetrahydrofuran scaffolds

Abstract

New thiazole hybrids were synthesized and evaluated for their in vitro cytotoxicity against a panel of human malignant cell lines. The key steps in the synthesis of hybrids 3?7 involved the initial condensation of appropriate aldononitriles with cysteine ethyl ester hydrochloride, followed by subsequent treatment of resulting thiazolines with diazabicycloundecene to form the thiazole ring. Bioisosteres 8 and 14 have been prepared after the stereoselective addition of 2-(trimethylsilyl)thiazole to the hemiacetals obtained by periodate cleavage of terminal diol functionality in the suitably protected d-glucose derivatives. The obtained analogues showed various antiproliferative activities in the cultures of several tumour cell lines. Hybrid 6 was the most potent in HeLa cells, exhibiting more than 10 and 4 times stronger activity than both leads 1 and 2, respectively. The most active compound in Raji cells was hybrid 12, which was nearly 2-fold more potent than the clinical antitumour drug doxorubicin. All analogues were more potent in A549 cells with respect to lead 1, while compounds 6 and 7 were slightly more active than doxorubicin. Preliminary structure?activity relationship analysis revealed that the presence of a cinnamate group at the C-3 position in analogues of type 7 increases the activity of resulting molecular hybrids.