Ultrasound-Assisted Extraction, Chemical Modification, Structural Characterization, and Activity Studies of Polysaccharides From Corn Silk.

The extraction methods significantly affect the yield and structure of polysaccharides. Based on single-factor experiments, response surface methodology optimized ultrasound-assisted extraction conditions for corn silk polysaccharides (CSP): liquid-to-solid 43 mL/g, extraction time 3 h, and ultrasonic power 640 W, yielding 5.83% CSP. Sulfated, phosphorylated, and selenylated derivatives (CSP-S, CSP-P, and CSP-Se) were prepared with substitution degrees of 0.6 and 0.4, and selenium content of 5.3%, respectively. After confirming structures by UV, FT-IR, SEM, monosaccharide, and Congo-red analyses, the bioactivities of the modified CSP were compared. All derivatives improved antioxidant capacity in vitro: phosphorylation boosted DPPH scavenging, while sulfation enhanced hydroxyl and superoxide anion radical elimination. Selenylation markedly inhibited the activities of α-amylase and lipase, and promoted glucose consumption in HepG2 cells, demonstrating hypoglycemic potential. Moreover, all polysaccharides enhanced RAW264.7 cell viability, phagocytosis, and nitric oxide (NO) release, with CSP-S being most effective. Chemical modifications markedly improved CSP bioactivities, highlighting their application prospects.