Extraction optimization, preliminary characterization, and bioactivities of polysaccharides from Silybum marianum meal

Silybum marianum meal is the major by-product in silymarin extraction, and most S. marianum meal is disposed of because of its huge output. To develop new physiologically active polysaccharides from S. marianum meal, two polysaccharide fractions (SMP2-1 and SMP4-1) were isolated and their innate primary chemical structure and bioactivities including antioxidant, hemolysis inhibitory, and -amylase and -glucosidase inhibitory activities were investigated. Structural analyses indicated that SMP2-1 had higher molecular weight (45.5kDa) than SMP4-1 (4.9kDa) and both comprised of arabinose, galactose, glucose, xylose, and mannose in a similar molar ratio, and the arabinose and galactose were the dominant sugars. FTIR results showed that SMP2-1 and SMP4-1 containing similar functional groups since they exhibited similar spectral characteristics. SMP2-1 exhibited better bioactivities than SMP4-1 including DPPH radical, ABTS radical, hydroxyl radical, and superoxide anion radical scavenging activities, hemolysis inhibitory, and -amylase and -glucosidase inhibitory. These data suggested that S. marianum polysaccharide fractions have potential to be explored as a functional food or complementary medicine.