Effects of Microwave Extraction Power on Physicochemical Properties, Structure, and Biological Activity of...

Panax ginseng is a well-known medicinal and edible plant rich in polysaccharides. However, research on the impact of microwave power (MP) on ginseng polysaccharides (GPs) remains limited. This study investigated the effects of varying MP (300-700 W) on the structure and bioactivity of microwave-extracted polysaccharide (MEP) using spectroscopy, and chromatography, and by evaluating antioxidant, antitumor, and immunomodulatory activities. The results were determined under the extraction conditions of 300 and 700 W that showed the polysaccharide yield (40.15% vs. 47.97%), content (85.77% vs. 88.60%), and the IC₅₀ values for ·OH scavenging ability (7.67 ± 0.25 mg/mL vs. 8.53 ± 0.18 mg/mL). The inhibition rates against HeLa cells at a polysaccharide concentration of 10 mg/mL were 26.78% and 1.08%, respectively. The release of nitric oxide (NO) at a polysaccharide concentration of 250 µg/mL was 2.23 and 1.82 µmol/L, respectively. Notably, the polysaccharides obtained at 700 W exhibited weak bioactivity, primarily due to severely damaged structure characterized by extensive O-glycosidic bond cleavage, a significant reduction in molecular weight, and the worst thermal stability. Overall, these findings emphasize how MP affects polysaccharide structure and function, offering critical insights for processing other plant-derived polysaccharides.