Comparative evaluation of extraction methods for Scorias spongiosa polysaccharides: Yield, bioactivity, and anti-aging potential

Scorias spongiosa, a highly nutritious edible fungus native to bamboo forests, is colloquially known as "Bamboo bird's nest". Polysaccharides are its primary bioactive ingredients, but comparative studies on their structural characteristics, in vitro antioxidant activities and anti-aging effects across different extraction methods remain scarce. In this study, Scorias spongiosa polysaccharides (SSPs) were extracted using five distinct techniques, including room-temperature water extraction (RWE, 37°C), hot water extraction (HWE), ultrasound-assisted water extraction (UAE), ultrasound-assisted acid extraction (UAE-H), and ultrasound-assisted alkali extraction (UAE-OH). Among these techniques, UAE-OH was identified as the most efficient approach for SSPs preparation, mainly owing to its higher polysaccharide yield (25.4 ± 3.77 %), improved purity (85.25 ± 4.13 %), and enhanced antioxidant activity. In addition, SSPs-UAE-OH possessed the robust anti-senescence effect by mitigating H₂O₂-induced oxidative damage, reactive oxygen species (ROS) accumulation, malondialdehyde (MDA) production and SA-β-gal expression in H9C2 cells. Structural analysis revealed that SSPs-UAE-OH primarily consists of glucose, with a molecular weight of 490 KDa, and FT-IR spectroscopy suggested its potential classification as an α/β-dextran. Furthermore, ultrasonic power was optimized to 500 W through a yield- and activity-guided approach, achieving an enhanced SSPs-UAE-OH yield (32.57 ± 1.57 %) and significantly improved the viability of H9C2 cells (82.33 ± 3.74 %). This study not only established an efficient extraction protocol for SSPs but also elucidated the structural basis of their antioxidant and anti-aging properties in vitro. These findings provide critical insights for developing SSPs-based functional foods.