Structure-Activity Studies on Therapeutic Potential of Thymoquinone Analogs in Pancreatic Cancer

Pancreatic cancer (PC) is one of the deadliest of all tumors. Previously, we were the first to show that Thymoquinone (TQ) derived from black seed (Nigella sativa) oil has anti-tumor activity against PC. However, the concentration of TQ required was considered to be high to show this efficacy. Therefore, novel analogs of TQ with lower IC50 are highly desirable. We have synthesized a series of 27 new analogs of TQ by modifications at the carbonyl sites or the benzenoid sites using single pot synthesis and tested their biological activity in PC cells. Among these compounds, TQ-2G, TQ-4A1 and TQ-5A1 (patent pending) were found to be more potent than TQ in terms of inhibition of cell growth, induction of apoptosis and modulation of transcription factor-NF-kappa B. We also found that our novel analogs were able to sensitize gemcitabine and oxaliplatin-induced apoptosis in MiaPaCa-2 (gemcitabine resistant) PC cells, which was associated with down-regulation of Bcl-2, Bcl-xL, survivin, XIAP, COX-2 and the associated Prostaglandin E2. From our results, we conclude that three of our novel TQ analogs warrant further investigation against PC, especially in combination with conventional chemotherapeutic agents.