Investigation of the cytotoxic effects of Pistachio hulls against osteosarcoma human cell line

This study aimed to evaluate the total phenolic, total flavonoid content and the antioxidant activity of pistachio (Pistacia vera L.) hull (PVHL) extracts and investigate the cytotoxic effect of different pistachio hull extracts on osteosarcoma U2OS cell line and study their impact on apoptosis, autophagy and heat shock protein 90. For this purpose, the pistachio hulls were extracted by soxhlet apparatus using methanol, ethanol, ethyl acetate and hexane as extraction solvents. The total phenolic content, total flavonoid content and antioxidant activity of each extract were determined by three colourimetric methods; Folin Ciocalteu method, AlCl3 method and DPPH radical scavenging assay, respectively. In order to investigate the osteosarcoma U2OS cells viability in response to treatment with each PVLH extract, MTT assays were performed. The obtained results were compared to find the extract that exhibit the best antioxidant activity and cytotoxic potential among other extracts. rt-PCR was used to investigate the effect of the extracts on both apoptosis and autophagy pathways by examining the gene expression of caspase3, bcl2, beclin1 and HSP90. Overall, the highest extraction yield (37.31%.), total phenolic content (121.93 ± 17.47 mg GAE/g), total flavonoid content (70.98 ± 2.44 mg RE/g), the antioxidant activity (IC50 =15.589 µg/mL) and cytotoxic effect on osteosarcoma cell line (IC50=171.95 ± 13.02 µg/mL) were determined in PVLH methanol extract. The assessments of the present investigation demonstrated that all PVLH extracts reduced the viability of osteosarcoma U2OS cells in a dose dependent manner and induced apoptosis in U2OS cells by upregulating the gene expression of caspase3.