Comparative Polyphenol Composition, Antioxidant and Anticorrosion Properties in Various Parts of <i>Panax ginseng</i> Extracted in Different Solvents

Abstract

Panax ginseng C.A. (P. ginseng) Meyer has been in use since ancient times for its therapeutic activities. Although several studies have investigated the roles of phytoconstituents in human and animal health, no comparative studies have been conducted to test the efficacy of P.ginseng leaf, fruit and root. Therefore, this study aimed to identify the antioxidant and anticorrosion activities of ginseng prepared using five different solvents. The methanolic fruit extract showed comparatively good activity in all assays. The total phenolic content (TPC) was higher in fruit (95.21 mg/g), followed by leaf (39.21 mg/g) extracted in methanol solvent compared other solvents. The total flavonoid content (TFC) of fruit methanolic extract was 50.21 mg/g, which was followed by fruit extracted in ethanol (41.33 mg/g). The same phenomenon was observed in all antioxidant studies. Through Ultrahigh Performance Liquid Chromatography (UHPLC), the presence of 23 phenolic components categorized as hydroxycinnamic acids, hydroxybenzoic acids and a few other groups that play a vital role in antioxidation was identified. Phenols such as chlorogenic acid (1002.2 μg/g), gentisic acid (854.21 μg/g) and rutin (165.32 μg/g) were found in higher amounts in fruit whereas leaf showed significant amounts of m-coumaric acid (185.32 μg/g) and p-coumaric acid (125.24 μg/g). The anti-corrosive property of the fruit extract of the ginseng with methanol as a solvent was analyzed for a copper specimen exposed to 1 M HCl medium and found to have 96% corrosion inhibition efficiency at a 1000-ppm concentration. The smooth surface of the specimen exposed to corrosive media shown in a field emission scanning electron microscope (FESEM) image confirms that the specimen was protected from corrosion, and energy-dispersive X-ray spectroscopy (EDX) spectra show that the loss of Cu is reduced in inhibited metal surface. Atomic force microscopy (AFM) images and surface roughness factor also validate the corrosion inhibition characteristic of ginseng plant extract.

Keywords

• ginseng
• phenolic compounds
• antioxidants
• corrosion
• copper
• FESEM-EDX