Study On Extraction And Structure Of Polysaccharides From Plantago Asiatica L. And Its Husk And Their Modification

Plantago asiatica L. is a species of Plantago family, widely distributed in China, especially in Jiangxi Province, such as in Ji’an, Ji’shui and Tai’he. The annual production of it is thousands of tons, and every year exports amounted to hundreds of tons. The seed of Plantago asiatica L. have been used for centuried in China with the activities of promoting diuretic, while the seed-coat(husk) containing substantial mucopolysaccharides were discarded as waste. Nowdays, In western countries the seed-coat has been used as health food supplyment which are well-known for its laxation effect, hypoglycemic effect, hypolipidemic effect, anti-inflammatory and immunological activity. In this research, for polysaccharides were extracted from the seeds of Ji’an Plantago asiatica L. and its husk with water and akali respectively. Their extraction, isolation, purification and primary structure elucidation were systematicly, Sulfuric acid modification was finally made on polysaccharides based on the research above. The main results were concluded as follows:1. The water extraction process of polysaccharides in Plantago asiatica L. was studied. By optimization with orthogonal design, the optimum extraction conditions were:5.45h at99℃, the ration of material to solvent is1:30(w/v), giving the yield of polysaccharides at13.79%compared with the theoretical predictions the relative error was6.67%.2. A water soluble polysaccharides WE-PLP was extracted with water from from Plantago asiatica L. and purified by Sephacry1TMS-400HR chromatographic column(5.5×60cm). The weight-average molecular weight demtermined by HPGPC was about1762kDa. The results of the physicochemical studies showed that WE-PLP contained87.32%of total sugar,0.98%of protein and17.85%of uronic acid. Arabinose, xylose, glucose and galactose were found to be the compositional monosaccharides in WE-PLP by GC, which the raito of1.00:4.68:0.23:0.18. After uronic acid reduction, the raito of compositional monosaccharides were1.00:4.59:0.50:0.18. By UV spectrum, WE-PLP has characteristic absorption at near280nm. By IR spectrum, WE-PLP has characteristic absorption of polysaccharides and protein, containing the β-pyranoid ring. By methylation analysis, it showed that the xylose were the dominant residues in WE-PLP with the forms of1,4-linked Xylp,1,2,4-linked Xylp and1,3,4-linked Xylp. The results revealed that the main chain was composed of1,4-linked xylopyranosyl residues.3. The sulfation conditions are studied to prepare sulfated water soluble of crude polysaccharides of Plantago asiatica L.. The optimum sulfation conditions that influenced the degree of substitution of polysaccharides were dertermined as follows:3h at88℃, the ration of chlorosulfonic acid to pyridine was1:2(v/v). The sulfated polysaccharides had characteristic absorption at near1255cm-1and820cm-1by IR, which demonstrated that the modification of sulfation was successful, with decreases of esterification reagent’s proportion, the degree of substitution was smaller and smaller.4. Alkaline extraction was used for the extracting the residued seeds of Plantago asiatica L.. The physicochemical properties of AE-PLCP were concluded as follows: the content of total sugar was82.84%, the content of protein was0.68%, the content of uronic acid was20.50%. By GC arabinose, xylose, glucose and galactose were found to be the compositional monosaccharides in AE-PLCP, with a ratio of1.00:15.41:63.95:1.29:2.58. After uronic acid reduction, the raito of monosaccharides were1.00:15.50:63.54:4.02:3.94. By UV spectrum, AE-PLCP has characteristic absorption at near280nm. By IR spectrum, AE-PLCP has characteristic absorption of polysaccharides and protein. By methylation analysis, it showed that AE-PLCP contained T-linked Araf、T-linked Xy1p,1,3-linked Araf、1,3-linked Xylp、1,4-linked Xylp、1,2,4-linked Xylp and1,3,4-linked Xylp residues. The xylose were the dominant residues with the forms of1,4-linked Xylp、1,2,4-linked Xylp、1,3,4-linked Xylp in AE-PLCP. The results revealed the main chain was composed of1,4-linked xylopyranosyl residues.5. A water soluble polysaccharides WE-PLHP was extracted with water from Plantago asiatica L. Husk and purified by Sephacry1TMS-400HR chromatographic column(2.4x60cm). The weight-average molecular weight demtermined by HPGPC was619,651Da. The results of the polysaccharides studies showed that WE-PLHP contained71.42%of total sugar,6.07%of protein and20.74%of uronic acid. Rhamnose, arabinose, mannose, glucose and galactose were found to be the compositional monosaccharides in WE-PLHP by GC, the ratio of them were2.24:1.87:1.00:3.24:3.49. After uronic acid reduction, the raito of monosaccharides were2.27:1.81:1.00:3.28:10.73. By IR spectrum, WE-PLHP has characteristic absorption of polysaccharides and protein, containing the β-pyranoid ring. Methylation analysis showed that glucose was the residues in WE-PLHP with the forms of T-linked Glcp,1,3-linked Glcp,1,6-linked Glcp and1,3,6-linked Glcp. Galactose with the froms of T-linked Galp,1,3-linked Galp,1,4-linked Galp,1,6-linked Galp and1,3,6-linked Galp. Rhamnose were T-linked Rhap and1,2-linked Rhap. Arabinose were T-linked Araf,1,4-linked Araf,1,2,4-linked Araf.Xylose were1,4-linked Xylp and1,2,4-linked Xyl.6. Alkaline extraction was used for the extracting the residued of Plantago asiatica L.Husk, then purified by Sephacry1TMS-400HR chromatographic column(2.4x60cm). The weight-average molecular weight was about498,217Da by HPGPC. The physicochemical properties of AE-PLHP were concluded as follows: the content of total sugar was59.19%, the content of protein was6.04%, the content of uronic acid was10.80%. Rhamnose, arabinose., xylose, mannose, glucose and galactose were found to be the compositional monosaccharides in AE-PLHP by GC with the ratio of2.46:1.78:4.78:1.00:24.38:2.52. After uronic acid reduction, the raito of monosaccharides were2.31:1.71:4.69:1.00:23.92:3.90. By IR spectrum, AE-PLHP has characteristic absorption of polysaccharides and protein, containing the β-pyranoid ring. Methylation analysis showed that glucose were the residues in AE-PLHP with the froms of T-linked Glcp,1,2-linked Glcp,1,3-linked Glcp,1,6-linked Glcp and1,3,4,6-linked Glcp. Xylose with the froms of T-linked Xylp,1,4-linked Xylp,1,2,4-linked Xylp and1,3,4-linked Xylp. Galactose with the forms of T-linked Galp,1,6-linked Galp,1,2,3-linked Galp,1,3,6-linked Galp,1,2,3,6-linked Galp and1,3,4,6-linked Galp. Arabinose with the forms of T-linked Araf and1,3-linked Araf Rhamnose with the forms of T-linked Rhap and1,2-linked Rhap.