Novel Tetrahydrobenzo [b] Thiophene Compounds Exhibit Anticancer Activity through Enhancing Apoptosis and Inhibiting Tyrosine Kinase

Background: Developing new chemotherapeutic agents with molecular targets, larger margin of safety against normal cells and low cost is the target many scientists try to achieve.

Objective: The present study was undertaken to investigate the anticancer activity of a novel series of thiophene compounds and the molecular mechanisms associated.

Method: A series of novel heterocyclic compounds including pyrimidine derivatives (2, 3, 4, 5 8, 11, 12, 13, 14, and 15), thiophene derivatives (6, 7, and 10) and oxoisothiazolidine derivative (9) was synthesized from 4,5,6,7- tetrahydrobenzo[b] thiophene (1). The newly synthesized derivatives along with the parent compound were evaluated for their anticancer activity against human HepG2, MCF7 and HCT116 cell lines and compared to doxorubicin as a reference drug.

Results: Compound 7 was very selective in targeting only the colon cells. Compounds 1, 5, and 12 showed strong cytotoxic activities against the 3 cell lines at 6-16 μM without any apparent toxicity to the normal fibroblasts WI-38. They had DNA affinity at 29-36 μM. The three compounds enhanced apoptosis to varying degrees elevating the expression of Bax, caspase 9 and caspase 3 in HepG2. Compound 5 was the most potent analogue and was superior to the standard drug used in upregulating the apoptotic genes and inhibiting tyrosine kinase at 1 μM. The IC50 value for compound 5 against TK was 296 nM.

Conclusion: Taken together, this study presents some thiophene scaffolds as auspicious hits for further optimization as specific antiproliferative agents against cancer cells and promising tyrosine kinase inhibitors at nanomolar concentrations.