Steam explosion-induced structural remodeling of <i>Auricularia auricula</i> polysaccharides enhances anti-aging efficacy in <i>Drosophila melanogaster</i>.

This paper studied the physicochemical properties and bioactivity of <i>Auricularia auricula</i> polysaccharides (AAPs) before and after steam explosion (SE) pretreatment. AAPs consisted mainly of mannose, galactose, and glucose; SE pretreatment shifted monosaccharide proportions and reduced the weight-average molecular weight to 3.37 × 10⁵ Da. Fourier transform infrared spectroscopy showed that SE did not alter the fundamental functional groups of the polysaccharides. Thermal stability was enhanced after SE, as evidenced by scanning electron microscopy, which revealed a transition from a dense architecture to a more open, stratified microstructure with increased surface roughness. Compared with the control (AAP-CK), the SE-treated group (AAP-SE) exhibited enhanced <i>in vitro</i> antioxidant capacity. Dietary supplementation with 0.0312% AAP-SE significantly extended the average lifespan of <i>Drosophila melanogaster</i> by 28.44% in females and 22.08% in males. In fruit flies, AAP-SE enhanced antioxidant enzyme activities, increasing superoxide dismutase by 67.32% and glutathione peroxidase by 2.61-fold in males, while reducing malondialdehyde levels by 42.75% in females. Furthermore, fruit flies fed AAP-SE showed improved resistance to hydrogen peroxide-induced oxidative stress and starvation stress, with gender-specific effects. These results suggested that SE pretreatment effectively enhanced the antioxidant and anti-aging activities of AAPs, suggesting their potential as natural lifespan-extending antioxidants.