Decoding glycome of Astragalus membranaceus based on pressurized liquid extraction, microwave-assisted hydrolysis and chromatographic analysis

Carbohydrates in herbs are a relatively untapped source of new drugs and health beneficial ingredients. Their analysis has been developed as a novel aspect in quality control and herbal glycomics. In this study, glycome of Astragalus membranaceus was decoded based on optimized pressurized liquid extraction (PLE), microwave-assisted acidic hydrolysis (MAAH) and comprehensive chromatographic approaches. Twelve saccharides including sucrose, galacturonic acid, mannitol, fructose, rhamnose, ribose, arabinose, fucose, xylose, mannose, glucose and galactose were quantitatively analyzed by GC-MS and HPLC-CAD (charged aerosol detectors). Different columns, including Prevail Carbohydrate ES, XBridge Amide and CARBOSep CHO-820 CA for HPLC-CAD analysis, were compared for evaluation of oligosaccharides. The polysaccharides in water extract of Astragalus membranaceus were characterized by high performance size exclusive chromatography (HPSEC) combined with multiple angle light scattering detection (MALSD) and refractive index detection (RID). The results showed that A. membranaceus contained more than 108.5mgg(-1) free sucrose and small amounts of glucose 9.6-26.0mgg(-1) and fructose 8.7-22.9mgg(-1). While its polymeric carbohydrates were composed of glucose 71.0-162.3mgg(-1), galacturonic acid 52.0-113.4mgg(-1), arabinose 22.8-54.4mgg(-1) and small amounts of galactose, rhamnose, xylose and mannose. CARBOSep CHO-820 CA showed its potential in simultaneously analyzing oligosaccharides and uronic acid, especially only the environment-friendly water mobile phase was used. HPSEC-MALSD-RID showed that there were three different molecular weight distributions of polysaccharides in A. membranaceus and the average molecular weight were 21901.1, 2038.5, and 353.4kDa. Hierarchical clustering analysis and principal component analysis demonstrated that A. membranaceus from different regions showed variations both in free and polymeric carbohydrates, which indicated that carbohydrates should be evaluated for the proper quality control of A. membranaceus. Rha, Ara, Xyl, Man and Gal were found to be the main elements for quality evaluation of polymeric carbohydrates in A. membranaceus by factor analysis. The strategy for decoding the glycome based on chromatographic approaches including GC-MS, HPLC-CAD and HPSEC-MALSD-RID after pressurized liquid extraction and microwave-assisted hydrolysis could be applied for carbohydrates profiling in herbs and beneficial for their quality control.

Effect of sample preparation on components and liver toxicity of Polygonum multiflorum

It was shown that different extracts had significant differences in the toxicity of Polygonum multiflorum. In this study, the effect of sample preparation on components and liver toxicity of different extracts from P. multiflorum were determined. Hepatoxic components were discovered based on biomembrane extraction. Comparative chemistry and toxicology between ethanol and water extracts were also performed. The results showed that ethanol extract had much stronger hepatotoxicity, the content of emodin-8-O-β-d-glucopyranoside, physcion-8-O-β-d-glucopyranoside, emodin and physcion was significantly higher in ethanol extract than in water extract, while the human hepatocytes extraction showed that 2,3,5,4'-tetrahydroxystilbene-2-O-β-d-glucopyranoside, emodin-8-O-β-d-glucopyranoside, physcion-8-O-β-d-glucopyranoside, emodin and physcion had interaction with human hepatocytes. The hepatotoxic effect of these components was investigated on human hepatocytes LO2 cells and emodin-8-O-β-d-glucopyranoside, physcion-8-O-β-d-glucopyranoside, emodin and physcion were finally confirmed to be, at least partial, hepatotoxic components. The results showed that sample preparation has significant effect on components in extracts of P. multiflorum especially the components related to hepatotoxicity. Water extract, the conventional administration form of Chinese herbs, is prefer for phytotherapy before well understanding their chemistry and biological activities.