Isolation of Gingerols and Its Preventive Effect on Insulin Resistance of HepG2 Cells

Objective: To investigate the prevention effect of gingerols on insulin resistance of HepG2 cells, extraction and isolation of ginger gingerols were carried out. Methods: The crude extract of gingerols were extracted by using ethanol and water bath oscillation. The crude extract of gingerols were separated and purified by ethyl acetate extraction and petroleum ether. The antioxidant activity of gingerols were determined using 1,1-diphenyl-2-picrhydrazyl (DPPH) and 2,2'-biazo-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS). Insulin resistance model of HepG2 cells were constructed, and the effects of gingerols on glucose consumption, superoxide dismutase (SOD), catalase (CAT) activity and PI3K/AKT pathway related gene expression were determined. Results: The optimum extraction conditions determined by orthogonal experiment were as follows: Solid-liquid ratio of 1:50 g/mL, extraction time of 80 min, ethanol volume fraction of 60%, extraction temperature of 50 ℃. Under these conditions, the yield of gingerols was 1.885%±0.071%. After extraction with ethyl acetate and petroleum ether, gingerols content was more than 34.55%. Antioxidant analysis showed that the semi-scavenging concentrations (EC₅₀) of gingerols on DPPH and ABTS⁺ were 0.501 and 0.111 mg·mL⁻¹, respectively. After treating with 25 μg·mL⁻¹ insulin for 48 h, cells exhibited reduced glucose consumption (P<0.05). Gingerols treatment significantly increased glucose consumption, SOD and CAT activities in a dose-dependent manner (P<0.05). In addition, the expressions of PI3K, IRS-2 and AKT genes were significantly up-regulated in gingerols treatment group (P<0.05), and the expressions of GSK-3β, FoxOI and PEPCK were significantly down-regulated in gingerols treatment group. Conclusion: Gingerols had desirable antioxidant activity, and also prevented insulin resistance through PI3K/AKT pathway.