Study On Isolation, Purification, Biochemical Identification And Function Of Polysaccharide From Semen Raphani

Semen Raphani that is known as a traditional Chinese medicinal plant,has the age-old history and broad source. It possesses lots of physiological functions such as antibacterial, antihypertensive, facilitating expectoration, suppressing cough and relieving dyspnea, strengthening gastrointestinal movement and anti-adrenergic. At present,most researchs of Semen Raphani were focused on SFN and alkaloid extracted from it,and few were reported on Polysaccharide.In this thesis, the extraction, isolation, purification, gradation and physical-chemical characteristics, as well as the impact of Polysaccharide from Semen Raphani on antimicrobial and preservation were studied. This research provides scientific reference for the further study and development of Semen Raphani as a Chinese medicinal plant.On the basis of single factor experiments, orthogonal design was adopted to search the optimum technological conditions for hot water extraction and microwave-assisted extraction. The result showed that optimum parameter as follows:75°C of extraction temperature,3h of extraction time,l:35 of the solid-solvent ratio for hot water extraction,and the extraction ratio of polysaccharides at 6.85%;while microwave power at 540w, 10min of the microwave extraction, material and liquid in the proportion of 1:20, and the extraction ratio of polysaccharides at 5.63%. The comparition on extracting efficiency between microwave-assisted extraction and water extraction indicated the advantages of microwave-assisted technique over traditional extraction method, that it took shorter time, consumed low energy and had high extraction ratio. And the optimum technological conditions for alcohol deposit of Polysaccharide was material and ethanol in the proportion of 1:4,100% of ethanol concentration, 4h of depositing time.For find the optimum method to remove the protein from rude Polysaccharide, optimum parameter of three methods, including Sevag, thicloroacetic acid, and thicloroacetic acid-n-butyl alcohol were studied and compared. The results revealed that the scheme of trichloroacetic acid-n- butyl alcohol were better than others. When the polysaccharides were added trichloroacetic acid-n- butyl alcohol(V/V=1:15) half as much as Polysaccharide solution, stirred for 30 minutes, and put quietly for one hours, it had higher percentage of removed protein which was 68.68% and lower percentage of lost Polysaccharide which was 14.71%.Based on the comparition between tow methods for removal of pigments,activated charcoal and H₂O₂, the result showed the H₂O₂ method was highter on decolorization rate, while the activated charcoal method was highter on the loss rate of polysaccharides.The product named SRP was graded with DEAE-cellulose column chromatography and was eluted with phosphate, solution of NaCL and NaOH respectively. It got one Polysaccharide monomers which was eluted with phosphate named SRPa. Then it was futher purified with gel filtration chromatography (Sephadex G-200), however was singular peak. The identification of purity implied that SRPa was homogeneous components. The molecular weight was identified by Sephadex G-200 column chromatography and HPLC with the results of 60228 and 59401 separately.The MIC text showed that SRP had stronger inhibitory effect on Aspergillus niger with the MIC 10g/L. When SRP used as preservation material, it could decrease the nutrition-lost and weight-lost rate of fruit, while delayed the senescent course during the storage period.