Physicochemical properties and cosmetic benefits of polysaccharide fractions from Zizania latifolia precipitated by different ethanol concentrations

Four polysaccharide fractions (designated as ZLPF-60, ZLPF-70, ZLPF-80, and ZLPF-90), extracted from the swollen culms of Zizania latifolia, were obtained by precipitation with varying ethanol concentrations (60, 70, 80, and 90 %, v/v). Their physicochemical properties and in vitro cosmetic benefits, including antioxidant activity, moisture absorption capacity, moisturizing efficacy, and whitening effect, were investigated. The results demonstrated that, with increasing ethanol concentration, the combined content of uronic acids and sulfates, zeta potential, and average molecular weight (Mw) decreased, while the particle size initially increased and then decreased. These fractions were identified as heteropolysaccharides composed of rhamnose, arabinose, galactose, glucose, xylose, mannose, galacturonic acid, and glucuronic acid in different proportions. FT-IR analysis confirmed these fractions as naturally sulfate-containing polysaccharides, and SEM revealed their diverse surface morphologies. Moreover, these fractions exhibited scavenging activities against DPPH and hydroxyl radicals, as well as ferric ion-reducing power. Among them, ZLPF-70 showed the strongest activity, followed by ZLPF-60. The moisture absorption properties of these fractions were superior to sodium alginate, and their moisturizing capabilities surpassed glycerol, particularly for ZLPF-60 and ZLPF-70. Notably, ZLPF-60 outperformed ZLPF-70 in inhibiting tyrosinase, especially tyrosinase diphenolase, achieving an inhibitory effect comparable to that of phenylethyl resorcinol. Both ZLPF-60 and ZLPF-70 demonstrated distinct cosmetic benefits. Furthermore, correlation analysis revealed that the negative charge density, Mw, and the high abundance of arabinose and galactose were the primary contributors to the observed cosmetic benefits.