1Materials
X-4 binocular microscope micro melting point tester (thermometer uncorrected, Beijing Tektronix Instrument Co., Ltd.); INOVO 400 MHz (Varian, USA) nuclear magnetic resonance spectrometer with TMS as the internal standard; HPMS5973 mass spectrometer (Hewlett-Packard, USA); TENSOR27 infrared spectrometer (Bruker, Germany). Silica gel for column chromatography (200-300 mesh), silica gel GF254 for thin layer and silica gel H for thin layer (Qingdao Ocean Chemical Factory). Malan was collected in Guiyang City, Guizhou Province, and the original plant was identified as Malan by Prof. Chen Deyuan of Guiyang College of Traditional Chinese Medicine, and the specimen was preserved in the Research Center for Quality Control of Natural Medicines of Guizhou Normal University.
2 Extraction and separation
Malan 10kg, 80% ethanol reflux extraction 3 times, combined extracts, decompression recovery solvent to no alcohol flavor, add the appropriate amount of water dispersion dissolution, respectively, with petroleum ether, ethyl acetate and n-butanol extraction. The ethyl acetate extracted portion was separated by column chromatography, and 6 fractions were obtained by gradient elution with petroleum ether: ethyl acetate solvent system. The first stream was separated on a silica gel column, eluted by a petroleum ether-ethyl acetate (30:1) system; the second stream was separated on a silica gel column, eluted by a petroleum ether-ethyl acetate gradient elution (20:1 5:1); the third stream was separated on a silica gel column, eluted by a petroleum ether-acetone (20:1) system to obtain the compound -polysaccharides; the fourth stream was separated on a silica gel column, eluted by a petroleum ether-ethyl acetate (10:12:1) system; the fifth stream was separated on a silica gel column, eluted by a petroleum ether-acetate (10:12:1) system. The 4th stream was on a silica gel column, eluted by petroleum ether-ethyl acetate (10121) system; the 5th stream was on a silica gel column, eluted by petroleum ether-ethyl acetate (10121) system; the 6th stream was on a silica gel column, eluted by chloroform-methanol (201) system. The structure of the obtained -polyserol was identified as the target compound.