Sildenafil (VIAGRATM): A Promising Anticancer Drug Against Certain Human Cancer Cell Lines

Sildenafil has been identified as the first agent for treating male erectile dysfunction and is a selective inhibitor of phosphodiesterase 5 (PDE5). Its chemical structure consists of three moieties named; 1-methyl-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-7(6H)-one, 5-(2-ethoxy-1-ylsulfonyl)phenyl and 4-methylpiperazine. Many articles are reported the cytotoxic activity of each moiety individually. The combination into a single molecule (sildenafil) of these three structural features could have promising anti-cancer and cytotoxic effects. The study evaluated sildenafil cytototoxic activity in vitro against mammalian cell lines: MCF-7, HCT-116, HeLa cells and A-549 cells with their IC50 values. Sildenafil showed considerable cytotoxic activity (IC50 = 28.2 ± 0.92, 45.2 ± 1.5, 30.5 ± 0.87 and 60.5 ± 3.2 μg/mL) against HCT-116, MCF-7, A-549 and HeLa cells, respectively. HCT-116 was the most sensitive cell line towards sildenafil followed by A-549, A375, MCF-7 and HeLa cells. These findings shed light on the antitumor activity of sildenafil and its possible impact on potentiating of cytokines, antitumor and anti-inflammatory markers in tumour cells. These effects might be related to the structure feature of sildenafil.