Physicochemical properties, moisture retention, and biological activities of polysaccharides from Panax notoginseng separated by fractional precipitation

The dried root of Panax notoginseng is a medicinal and food ingredient. Panax notoginseng polysaccharides (PNPs) have physicochemical properties, which have not been fully elucidated. This study aimed to identify a method to separate the PNP fractions and investigate their activities. PNPs were prepared from roots by hot water extraction, deproteinization, and decolorization. PNP20, PNP40, and PNP60 fractions were isolated through stepwise ethanol precipitation at 20%, 40%, and 60% concentrations, respectively. The three polysaccharide fractions were characterized using chromatography, spectroscopy, and thermogravimetric analysis, and their moisture retention, antioxidant, and tyrosinase-inhibition properties were evaluated. Monosaccharide composition analysis showed that the three PNPs contained mannose (Man), galacturonic acid (GalA), glucose (Glc), galactose (Gal), and arabinose (Ara) in different molar ratios. HPGPC analysis demonstrated that the polysaccharides precipitated with higher ethanol concentrations had lower molecular weights (Mw). Furthermore, it was observed that all PNPs have certain moisturizing and hygroscopic properties and antioxidant activities, with PNP60 showing better antioxidant properties and a competitive mixture of hygroscopic properties and tyrosinase inhibition. The chemical composition and structural characteristics of PNPs could affect their functional attributes. PNP60 has the potential to be a moisturizer and antioxidant and could be used in the development of cosmetic ingredients.