Antitumor efficiency of novel fluoro-substituted 6-amino-2-phenylbenzothiazole hydrochloride salts in vitro and in vivo.

The purpose of this study was to investigate antitumor activity of novel fluoro-substituted 6-amino-2-phenylbenzothiazole hydrochloride salts in vitro and in vivo. A novel series of hydrochloride or dihydrochloride salts of the novel 2-(fluoro-substituted phenyl)-6-aminobenzothiazoles (5-7) have been prepared in multistep synthesis starting from 3- or 4-fluorobenzaldehydes and 2-amino-5-nitrothiophenol and evaluated for their antiproliferative activity against human cervical (HeLa), breast (MCF-7), colon (CaCO-2), and laryngeal (Hep-2) carcinomas and against fibroblast cell lines (WI-38). Also, antitumor activity of these compounds was evaluated in vitro and in vivo against murine melanoma (B16-F10), fibrosarcoma (FsaR), and squamous cell carcinoma (SCCVII). The tested compounds were found to exert good cytotoxic activity in vitro. The cytotoxic effect was selective, cell specific, and dose dependent, between 33 microM for MCF-7 and 110 microM for WI-38. Benzothiazoles reduced de novo protein and DNA synthesis up to 75%. All examined benzothiazoles had significant antitumor activity in vivo against melanoma B16-F10, fibrosarcoma, and squamous cell carcinoma. The best therapeutic results were achieved when therapy started 7 days after tumor cell implantation and when benzothiazoles were given repeatedly five times every 2 days, i.e., on day 7, 9, 11, 13, and 15 after transplantation of tumor cells.