Synthesis of Tetrahydrobenzo[ b]thiophene-3-carbohydrazide Derivatives as Potential Anti-cancer Agents and Pim-1 Kinase Inhibitors

Abstract

Background: Tetrahydrobenzo[b]thiophene derivatives are well known to be biologically active compounds and many of them occupy a wide range of anticancer agent drugs.

Objective: One of the main aim of this work was to synthesize target molecules not only possessing anti-tumor activities but also kinase inhibitors. To achieve this goal, our strategy was to synthesize a series of 4,5,6,7- tetrahydrobenzo[b]thiophene-3-carbohydrazide derivatives using cyclohexan-1,4-dione and cyanoacetylhydrazine to give the 2-amino-6-oxo-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbohydrazide (3) as the key starting material for many heterocyclization reactions.

Methods: Compound 3 was reacted with some aryldiazonium salts and the products were cyclised when reacted with either malononitrile or ethyl cyanoacetate. Thiazole derivatives were also obtained through the reaction of compound 3 with phenylisothiocyanate followed by heterocyclization with α-halocarbonyl derivatives. Pyrazole, triazole and pyran derivatives were also obtained.

Results: The compounds obtained in this work were evaluated for their in-vitro cytotoxic activity against c-Met kinase, and the six typical cancer cell lines (A549, H460, HT-29, MKN-45, U87MG, and SMMC-7721). The results of anti-proliferative evaluations and c-Met kinase, Pim-1 kinse inhibitions revealed that some compounds showed high activities.

Conclusion: The most promising compounds 5b, 5c, 7c, 7d, 11b, 14a, 16b, 18b, 19, 21a, 23c, 23d and 23i against c-Met kinase were further investigated against the five tyrosin kinases (c-Kit, Flt-3, VEGFR-2, EGFR, and PDGFR). Compounds 5b, 5c, 7d, 7e, 11b, 11c, 16c, 16d, 18c, 19, 23e, 23k and 23m were selected to examine their Pim-1 kinase inhibitions activity where compounds 7d, 7e, 11b, 11c, 16d, 18c and 23e showed high activities. All of the synthesized compounds have no impaired effect toward the VERO normal cell line.

Keywords: Thiophene; pyran; pyrazole; thiazole; triazole; tyrosine kinase..