Ultrasound-Assisted Treatment from Inonotus obliquus Polysaccharides: Extraction Optimization, Structures and Antioxidant Activity

This study examined the effect of sonication conditions on the extraction rate of Inonotus obliquus polysaccharides (IOPs) through a single-factor experiment. Meanwhile, the Box-Behnken design was utilized to optimize the sonication-assisted extraction technology. On the basis of polysaccharide yields, the optimal IOPs extraction rate (4.13%) was achieved with ultrasonic time (31 min), ultrasonic frequency (28 kHz), ultrasonic temperature (63℃) and a solid-to-liquid ratio of 1:20 g/mL. The empirical data obtained from these reactions closely align with the theoretical values generated by the mathematical model. Antioxidant experimental results indicated that the scavenging abilities of the polysaccharides from IOPs on DPPH radicals, hydroxyl radicals, and superoxide anion radicals were positively correlated with their concentration, with maximum scavenging rates of 64.1%, 65.7%, and 34.1%, respectively, suggesting that the IOPs possess strong antioxidant activity. The structure of the IOPs was analyzed using the ultraviolet and infrared spectra. The results revealed that IOPs were pyranose cyclic polysaccharides with β-glycosidic bonds, carbonyl groups, hydroxyl groups, and other functional groups. This confirms the feasibility of ultrasonic-assisted extraction for IOPs, indicating its potential application in pharmaceutical extraction research. This study laid a foundation for further development and utilization of Inonotus obliquus.