Mechanism of Unsaponifiable Matter from Walnut Oil on D-Galactose-Induced HepG2 Cells

Aging is an inevitable biological phenomenon that encompasses numerous physiological changes. Oxidative stress is one of the main reasons for exacerbating the symptoms of aging, and resistance to oxidative stress is an effective means of reducing the symptoms of aging. The unsaponifiable matter (USM) in walnut oil is a kind of highly active ingredient, which has important development and application value. The effect of USM from walnut oil on HepG2 cells was investigated using an in vitro D-galactose-induced senescence model of HepG2 cell and cell viability, cellular oxidative stress levels, intracellular inflammatory factor content, and intracellular liver function levels were used as evaluation indexes. The impact of USM on D-galactose-induced damage in HepG2 cells was examined using Western Blot analysis. The findings indicated that pre-treatment with USM at concentrations of 50, 75, 100 μg/mL effectively mitigated the reduced viability of D-galactose-damaged HepG2 cells, while also enhanced the enzymatic activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). The concentrations of lipid oxidation products, including malondialdehyde (MDA), inflammatory cytokines (TNF-α, IL-1β, IL-6), alanine and aspartate aminotransferase (ALT, AST), and alkaline phosphatase (AKP), exhibited a decrease. Furthermore, USM were found to enhance the translocation of nuclear factor E2-related factor 2 (Nrf2) into the cytoplasm and nucleus, leading to the activation of downstream target proteins such as heme oxygenase-1 (HO-1) and quinone NADH dehydrogenase 1 (NQO1). The USM of walnut oil have been shown to inhibit the senescence induced by D-galactose in HepG2 cells through activation of the Nrf2/Keap1 signaling pathway. The results aimed to provide theoretical references for the development of functional products from walnut oil.