Pomegranate Peel Extract as 6-Phosphogluconate Dehydrogenase (6PGD) Inhibitor for Treatment of Breast Cancer

Targeting the enzymes of Pentose Phosphate Pathway (PPP) has been emerged as a novel strategy for treatment of cancer. 6-phosphogluconate dehydrogenase (6PGD) is third enzyme of PPP and converts 6-phosphogluconate (6-PG) into ribulose 5-phosphate (R-5-P) and produces NADPH. The overexpression of 6PGD has been reported in many human cancers especially in breast cancer and is emerged as the potential anti-cancer drug target. The current study is focused to screen an already established library of plant extracts against 6PGD, among which Pomegranate peel extract showed significant 6PGD inhibitory activity with IC50 value = 0.090 μg/mL. Pomegranate peel competitively inhibited NADP+ and 6-phosphogluconate to 6PGD enzyme having Ki constant value = 12.72 ± 5.54 ng/mL. Moreover, anti-breast cancer activity against MCF-7 cells determined Pomegranate peel as the potent inhibitor of cancerous cells with IC50 value = 3.138 μg/mL. Toxicity profiling of pomegranate peel extract (2000mg/kg) did not show any adverse effect on mice. Moreover, Ont the base of literature a library of known compounds of pomegranate was prepared and established and screened against 6PGD for the identification of actual responsible phytochemicals of 6PGD activity by using molecular docking. Computational tools were used to evaluate selected potent hits. Out of 26 compounds, three potent phytochemicals (Procyanidin, Delphinidin and Cyanidin) exhibited the best binding affinities with 6PGD. In addition, these phytochemicals displayed the best favorable hydrogen bonding, binding energy, and protein-ligand interactions as compare to 3PG. Molecular dynamics simulation suggested that these hits form a stable binding complex with the active site of 6PGD. These findings suggest that Pomegranate peel and its secondary metabolites as the potent inhibitors of 6PGD and the best drug candidate for treatment of breast cancer.