[Quality evaluation methods of Poria based on yield and content of alkali extracted polysaccharide]

To improve the quality control methods of Poria and develop and utilize its resources fully, alkaline extraction was used in this study to determine the yield and content of alkali-soluble polysaccharides of Poria. The alkali-soluble extracts of Poria were obtained according to the optimum extraction conditions on the basis of single-factor test, and 30 batches of samples were determined. The structure and chemical composition of the alkali-soluble extracts was characterized by high-performance gel permeation chromatography(HPGPC), Fourier transform infrared spectrometry(FT-IR), nuclear magnetic resonance(NMR) spectroscopy and high-performance liquid chromatography(HPLC) with 1-phenyl-3-methyl-5-pyrazolone(PMP-HPLC). The results showed that the content of the alkali-soluble extracts was in the range of 46.98%-73.86%. The main component was β-(1→3)-glucan, and its molecular mass was about 1.093×10~5. Further, the content of alkali-soluble polysaccharides of Poria was measured by UV-Vis spectrophotometry and HPLC coupled with the evaporative light scattering detector(HPLC-ELSD), and 30 batches of samples were measured. The results indicated that the content of alkali-soluble polysaccharides determined by UV-Vis spectrophotometry was in the range of 73.70%-92.57%, and the content of samples from Hubei province was slightly higher than that from Yunnan province, Anhui province and Hunan province. The content of alkali-soluble polysaccharides determined by HPLC-ELSD was in the range of 51.42%-76.69%, and the samples from Hunan province had slightly higher content than that from the other three provinces. The content determined by UV-Vis spectrophotometry was higher than that by HPLC-ELSD. However, the content determined by HPLC-ELSD was close to that of alkali-soluble extract, which could accurately characterize the content of alkali-soluble polysaccharides in Poria, and the method was simple and repeatable. Therefore, it is recommended that the quantitative analysis method for alkali-soluble extract and alkali-soluble polysaccharides by HPLC-ELSD be used in the quality standards of Poria in Chinese Pharmacopeia.