Pistachio Green Hull Extract Induces Apoptosis Through Multiple Signaling Pathways by Causing Oxidative Stress on Colon Cancer Cells

Background: Pistachio is considered to be one of the fifty foods with the highest antioxidant effect. However, the anticancer effect mechanisms of this plant extracts are unknown.

Objective: The aim of this study is to investigate the anticancer effect of different extracts from green hull of pistachio.

Methods: The cytotoxic effects of different solvent extracts on cancer and normal cells were examined by cell viability assay and flow cytometric analysis. The levels of apoptoticgene and protein were investigated by Western Blot and ELISA,and qPCR. Intracellular free radical exchange was determined by oxidativeand nitric oxide analyses. DNA damage level was measured by 8-OHdG test. Phenolic and free fatty acid components were examined by LC-MS/MS and GC-MS, respectively.

Results: It was determined that n-hexane fraction showed the highercytotoxic effect on cancer cells. Oxidative and cell cycle analyses indicated that the n-hexane fraction arrested cell cycle of HT-29 at the sub-G1 phase by increasing DNA damage through oxidative stress. In addition, gene expression analysis of the HT-29 treated with the n-hexane fraction indicated that apoptotic and autophagic gene expressions were significantly up-regulated. LC-MS/MS analysis of then-hexane fraction revealed the presence of 15 phenolic compounds, containing mainly gallic acid and catechin hydrate, and GC-MS analysis determined presence of the following fatty acids:9-octadecenoic acid, 9,12-octadecadienoic acid and hexadecenoic acid.

Conclusion: Based on these grounds, we suggest that n-hexane fraction of pistachio green hull damages DNA, arrests the cell cycle at the G1 sub phase, and induces apoptosis through oxidative pathways in colon cancer.

Keywords: Apoptosis; anti-cancer agent; colorectal cancer; cytotoxicity; oxidative stress; phenolic compounds..