Effects of different extraction techniques on the structural, physicochemical, and bioactivity properties of heteropolysaccharides from Platycodon grandiflorum roots

In this study, two different extraction methods, enzymatic-assisted extraction (EAE) and ultrasonic-assisted extraction (UAE), were used to extraction of polysaccharides from the roots of Platycodon grandiflorum (PGR), and the preliminary characterization of the purified polysaccharide (PGP1 extracted with EAE and PGP2 extracted with UAE) were analyzed. The data implied that the yield of the polysaccharide obtained by UAE (12.01 ± 0.11%) was significantly higher than that of EAE (9.06 ± 0.07%). Meanwhile, Chemical composition analysis revealed that both PGP1 (6.6 kDa) and PGP2 (5.4 kDa) were comprised of eight monosaccharides with different molar ratios. Preliminary characterization analysis including FT-IR spectra, NMR analysis, X-ray diffraction, Congo red experiment, and thermogravimetric analysis were investigated. The result illustrated that PGP1 and PGP2 have similar chemical composition and functional groups, and both have crystalline and triple helix structure. Moreover, PGP2 demonstrated better water (4.94 ± 0.14 g/g) and oil (2.69 ± 0.016 g/g) retention capacity than PGP1, and also showed higher bile binding ability and pancreatic lipase inhibition activity. However, PGP1 presented higher inhibitory activities against α-amylase and α-glucosidase. Based on the above, these findings indicated that the two novel polysaccharides are worthy being developed as natural hypoglycemic and hypolipidemic agents.