Pine pollen extract alleviates ethanol-induced oxidative stress and apoptosis in HepG2 cells via MAPK signaling

Pine pollen extract (PPE) has various effects such as antioxidant, hypoglycemic and anti-obesity. However, the anti-ALD mechanism of PPE has rarely been studied. In this study, PPE was prepared and chemical components such as total protein, total sugars, total phenols, total flavonoids and polyphenol composition were determined. The effect of PPE on HepG2 cells after ethanol damage was also measured. HepG2 cells were pre-treated with 200 μg/mL and 400 μg/mL of PPE for 24 h followed by treatment with ethanol for 24 h. The results suggested that PPE significantly decreased the production of LDH, ROS and MDA. Meanwhile, the levels of GSH and SOD were also increased. The levels of Nrf2, HO-1 and Keap1 were upregulated after PPE treatment. Additionally, Bax were downregulated and Caspase3 activation was inhibited after PPE treatment. What's more, PPE also attenuated the ethanol-induced phosphorylation levels of MAPK in HepG2 cells. Three major phenols were identified as p-coumaric acid, catechins and caffeic acid. These results suggest that PPE can be effective against ALD by alleviating MAPK pathway-mediated oxidative stress and apoptosis. In conclusion, PPE is a natural product with hepatoprotective potential.