Optimization of the Best Polar Site for Antioxidant Activity of Panax ginseng Extract Based on Entropy Weight Method and Grey Relational Analysis Combined with Component Analysis

Objective: The differences in antioxidant activity of different polar parts of panax ginseng were investigated to screen the best active parts. Method: In this study, the water extract of Panax ginseng was extracted by petroleum ether, chloroform, ethyl acetate and n-butanol in turn. The contents of total phenolic acids, total saponins, total polysaccharides, total flavonoids, ginsenoside Rg1, ginsenoside Re and ginsenoside Rb1 in different polar parts were determined by high performance liquid chromatography (HPLC) and ultraviolet-visible (UV) spectrophotometer. The in vitro antioxidant activity of different polar parts was determined by DPPH free radical, ABTS⁺ free radical, hydroxyl radical, superoxide anion free radical and cell oxidative damage model. Combined with entropy weight method and grey relational analysis, the quality evaluation model of different polar parts of Panax ginseng was established. By weighting twelve quality characteristic indexes of different polar parts of Panax ginseng, the best antioxidant polar part of Panax ginseng was ultimately selected. Results: The differences in the components and antioxidant activity of different polar parts of Panax ginseng were obvious. Among them, the content of total phenolic acid, total flavonoids and ginsenoside Rb1 in n-butanol part was higher than that in other parts. The n-butanol part had the best antioxidant activity, and had certain scavenging ability to DPPH free radical, ABTS⁺ free radical, hydroxyl radical and superoxide anion free radical, and the corresponding IC₅₀ values were 0.14, 0.57, 0.92 and 0.75 mg/mL, respectively. In addition, combined with the quality evaluation model, the relative correlation degrees of range of different polar parts of Panax ginseng was 0.352~0.618, and the relative correlation degree of n-butanol part was the highest (0.618), which further indicated that the antioxidant activity of n-butanol part was the strongest. Conclusion: Based on the evaluation results of entropy weight method and grey correlation analysis, the n-butanol part was preliminarily selected as the most ideal antioxidant part of Panax ginseng, which would provide a theoretical basis for the research of Panax ginseng as a natural antioxidant and the development and application of Panax ginseng antioxidant food.