Study On Water - Soluble Polysaccharides From Artemisia

Artemisia rupestris L. is a perennial herb belonging to Compositae, Artemisia L., which is mainly located in Altai Mountain, Tianshan Mountain, Kunlun Mountain. The whole plant of Artemisia rupestris L.is widely used as medicinal material by Uighur. Artemisia rupestris L.is named as "yi zi hu ai man ni" by Uighur, which has a significant effect on the treatment of Carminative promoting blood circulation, digestion and some other dieases. According to many domestic and foreign reports, research about Artemisia rupestris L. is mainly focus on Flavonoids, Sesquiterpene and Alkaloids. In terms of polysaccharide from Artemisia rupestris L., only the extraction and antioxidant activity of crude polysaccharide has been researched, while, no investigation has illustrated polysaccharides from Artemisia rupestris L concerning structure analysis. In view of many activities of polysaccharide, further research has been carried on the polysaccharide of Artemisia rupestris L. in the paper.The response surface methodology was utilized to optimize ultrasonic wave-assisted the extraction of crude polysaccharides (YZHc) from Artemisia rupestris L.. The results showed the optimum conditions as follows: 1)liquid/solid ratio was 30 mL/g; 2)extraction temperature was 72℃; 3) extraction time was 2.5 h; 4)ultrasonic wave power is 350W.Under these conditions, the experimental value was 3.11%, which is almost consistent with predicted value.YZHc was deproteinated by the method of enzymatic and Sevage and decolorized by H2O2, YZHp was producted. The fraction YZH4, which get by acidic ethanol from YZHp, was dissolved in distilled water and purfied by DEAE Sephadex A-25, then the collected fractions dialyzed and freeze-dried were named as YZH4b. High performance liquid chromatography indicated that YZH4b was a homogeneity polysaccharide, and the average molecular weight of YZH4b was approximately 9333.Gas chromatography analysis demonstrated that YZH4b was composed of rhamnose (Rha), arabinose (Ara), xylose(Xyl), Mannose(Man), glucose (Glc), galactose(Gal), with a molar ratio of 1.0:14.7:2.4:7.2:19.6: 33.2.By means of IR spectroscopy, NMR spectra, the structure of YZH4b was identified. The results revealed that YZH4b was a kind of branched structure. The main chain was composed of 1â†'4 and 1â†'3 by Gal, Gal are substituted at 6-O. The side chain was composed of (1â†'4)-Rha, (1â†'3)-Ara, (1â†'3)-Xyl, (1â†'3,6)-Man,(1â†'3, 1â†'4, 1â†'6 or 1â†'3,4,6)-Glc and (1â†'3)-Gal. The terminal residue was composed of Ara and Glc.The free radical scavenging experiment illustrated that YZHc, YZH1, YZH2, YZH3, YZH4, YZH5 and YZH4b have significant scavenging potential against hydrolxyl and DPPH free radicals, and the clearance rate is correlated with the concentration of polysaccharide and degree purification of polysaccharides.When the concentration of YZH4b is 2.5mg/mL, the scavenging effect of YZH4b on hydrolxyl and DPPH are respectly 77.23% and 65.43%.