Extraction, purification, structural characterization, and anti-skin aging activity of a homogeneous polysaccharide from Durvillaea antarctica

As an edible algae with rich nutrients and high medicinal value, Durvillaea antarctica has certain potential in anti-aging, but there is currently limited research on the separation, purification and activity of its anti-aging active ingredients. We successfully extracted and purified a new β-(1,3)-D-glucan with a special branched structure from Durvillaea antarctica using subcritical water extraction combined with ultrafiltration membrane (SWE-UFM). The polysaccharide, named DAG-1, consists of glucose (92.70%) and has a weight-average molecular weight of 10149 Da. The GC–MS and 1D/2D NMR confirmed that DAG-1 was composed of 3)-β-D-Glcp-(1 → , → 3,6)-β-D-Glcp-(1 → , β-D-Glcp-(1 → and → 6)-α-D-Glcp-(1 → , and β-glycosidic linkages between these sugar units. Animal experiments showed that DAG-1 has significant anti-skin aging effects by inhibiting the reduction of superoxide dismutase (SOD) activity, accumulation of malonic dialdehyde (MDA), and decline in hydroxyproline (HYP) content in collagen fibers of D-gal-induced mouse skin. To further elucidate the mechanism of DAG-1, we found that DAG-1 can alleviate senescence in human dermal fibroblasts (HDFa), inhibit degranulation of human cutaneous mast cells (HCMC), and modulate inflammatory factors (TNF-α, IL-6) production. Additionally, DAG-1 may bind to c-KIT receptors and downregulate the expression of KITLG/KIT, regulating the growth and activation of mast cells, and thus alleviate skin aging. These findings suggest that DAG-1 is a potential anti-aging ingredient for functional food, cosmetic, and medicine development.