Characterization of an α-mannan from Pichia ethanolica and its potential applications in cosmetics

An α-mannan, designated PEEPS-1 with a weight-average molecular weight (Mw) of 71.1 kDa, was isolated and purified from Pichia ethanolica Y49. Structural elucidation by FT-IR spectroscopy, NMR spectroscopy, and methylation analysis indicated that PEEPS-1 possesses a backbone predominantly composed of (1 → 2)-linked α-D-mannopyranosyl residues. A cosine similarity model based on glycosidic linkage profiles was further employed to compare PEEPS-1 with previously reported α-mannans and quantitatively evaluate its structural uniqueness. In vitro assays showed that PEEPS-1 exhibited concentration-dependent antioxidant activity against DPPH, ABTS, and hydroxyl radicals, as well as moisture absorption and moisture retention properties under experimental conditions. In addition, PEEPS-1 displayed concentration-dependent hyaluronidase inhibitory activity with an EC₅₀ of 1.22 mg/mL. Molecular docking using a representative structural fragment suggested a potential interaction between PEEPS-1 and the active site of hyaluronidase, providing a possible explanation for the observed inhibitory activity. Overall, these results suggest that PEEPS-1 may serve as a promising bio-based polysaccharide for further investigation in cosmetic-related applications.