Effects of steam on polysaccharides from Polygonatum cyrtonema based on saccharide mapping analysis and pharmacological activity assays

Abstract

Background Polygonatum cyrtonema, one of origins of Polygonata Rhizoma (HuangJing in Chinese), is traditionally steamed repeatedly before being used as herbal medicine in China. However, there has no standard for steaming of HuangJing. Therefore, a comprehensive study for effects of steam on polysaccharides from Polygonatum cyrtonema based on saccharide mapping, a powerful method developed for polysaccharides analysis, and pharmacological activity are still necessary, which is helpful to explore the effect of steam on the physiochemical and biological activities of its polysaccharides and develop steaming standard of Polygonatum cyrtonema. Methods To explore the effect of steam on physiochemical and biological activities of P. cyrtonema polysaccharides (PCP), six polysaccharides named PCP0, PCP1, PCP2, PCP3, PCP4 and PCP5 were extracted from the herb consecutively steamed for 0–5 times, respectively. Their molecular weight distribution, monosaccharide composition and PACE fingerprints were investigated through HPSEC-MALLS-RID, HPAEC-PAD and saccharide mapping based on polysaccharides analysis by using carbohydrate gel electrophoresis (PACE) and HPTLC, respectively. In addition, their antioxidant ability and immunostimulatory activities on RAW 264.7 cells in terms of NO production and phagocytosis were compared. Results Results suggested that molecular weights could be changed during steam, which increased by first steaming and then decreased with further steaming though all polysaccharides’ molecular weights were 105-107 Da. They all showed irregularly spherical conformation in aqueous solution based on AFM imaging. Their monosaccharide composition and PACE fingerprints were significantly different after steaming, i.e., galactose increased while glucose and mannose decreased, and β-1,4-Galp appeared while β-1,4-Manp increased, after steaming. Steamed PCP significantly increased scavenging activity against ABTS radicals, while PCP0 had the best immunostimulatory effect on RAW 264.7 in terms of NO production and phagocytosis. Conclusions In summary, steam significantly affected the chemical composition and bioactivities of polysaccharides from P. cyrtonema. Considering the balance beneficial effects of steaming on antioxidant and immunopotentiation activities of PCP, 2 times of continuous steam is the optimal choice under the given conditions.

Quality Evaluation of Ophiopogon japonicus from Two Authentic Geographical Origins in China Based on Physicochemical and Pharmacological Properties of Their Polysaccharides

“…The assay of ABTS radical scavenging was slightly modified according to the method of Chen et al [ 23 ]. In brief, 7 mmol/L ABTS aqueous solution and 2.5 mmol/L potassium persulfate aqueous solution were mixed in a ratio of 1:1, and then stood in dark for 12 h. This solution was diluted with deionized water to reach a 0.7 ± 0.05 absorbance value at 734 nm, and obtained the ABTS working solution.…”

Health-Promoting Activities and Associated Mechanisms of Polygonati Rhizoma Polysaccharides

“…Polygonati Rhizoma polysaccharides and oligosaccharides could be decomposed into monosaccharides during the repeated steaming process [ 55 ]. Monosaccharide composition differed after steaming: the content of Gal and β-1,4-mannopyranose increased and the content of Glu and mannose (Man) decreased, while glycosidic linkage β-1,4-galactopyranose appeared [ 17 ]. The FTIR spectra showed that Polygonati Rhizoma polysaccharides possessed different degrees of esterification [ 56 ].…”

“…PCP-1 possessed a (2→1)-linked β- D -Fruf backbone, as well as (2→6)-linked β- D -Fruf side chains with an internal α- D -Glc p in neokestose form [ 68 ]. PCP0-PCP5 (10 5 -10 7 Da), extracted consecutively and steamed for 0–5 times, showed irregularly spherical conformation in aqueous solution [ 17 , 69 ]. The process of steaming led to significant structural changes of PCP, including molecular degradation, aggregation, and depolymerization [ 16 ].…”

“…The process of steaming led to significant structural changes of PCP, including molecular degradation, aggregation, and depolymerization [ 16 ]. The molecular weights of PCP changed during repeated steaming, first increasing with steaming and then decreasing with further steaming [ 17 ]. P. cyrtonema fructan contained a (2→6) linked β- D -Fruf residue backbone along with an internal α-D-Glc p residue and two (2→1) linked β-D-Fruf residue branches [ 70 ].…”

“…If considering total saccharides, fructose (Fru) and phospholipids as the main quality indicators, four cycles of steaming-drying should be the ideal method to obtain better taste, flavor and functionality [ 14 ]. If considering antioxidant and immunopotentiation activities, two cycles of continuous steaming-drying would be the best choice [ 17 ].…”