| Melia azedarach, belonging to the family Meliaceae has been favored as pesticide and Chinese traditional medicine. In recent years, up to now, a great diversity of low-molecular weight constituents including hydrocarbons, terpenoids, limonoids, naphthoquinines, amine acid, etc from the plant Melia azedarach have been elaborated; however few reports have been concerned with the polysaccharide and fatty acid from the fruits of this species. In order to fully utilize the resource, the extraction, purification, structure elucidation and potential biological activities of its fruits have been studied. The chemical components of fatty acid and synthesis of conjugated linoleic acid from its oil were carried out as well in this paper. Main results achieved in this research are as follows:1. The optimum extraction technology of polysaccharide from fruits (MPS) was studied by single-factors experiments and orthogonal designs. The results showed that the condition of adding 80 percentage of ethanol concentration at the temperature of 85℃, and with the extracting time of two hours by one time when the ratio of material to water is 1:20 is recommended. The crude polysaccharide was isolated and purified by means of DEAE-52 cellulose column, Sephadex G-100 column. Three fractions were isolated from MPS, which occupies about 61.2% of MPS. Among them, MPS-1 was further identified by the methods of Sephadex G-200 and SDS-PAGE.2. Primary structure of MPS and MPS-1 were analyzed by the methods of Gel-chromatography and GC-MS, which indicated that the former contains monosaccharides of Arab, Man and gluc. Their molar ratio is 3.37:4.86:1.0; while the latter contains monosaccharides of Arab and Man, and the ratio is 1.13:1.0. Further specific glycosidic linkage in MPS-1 were investigated by IR, 1H-NMR, 13C-NMR, periodate oxidation and smith degradation. The results revealed that MPS-1 is of a higher branched structure and α -conformation. The main chain is composed of (1→4)-linked-Man. Some of them were substituted at 6-O. The side chain is composed of major (1→6) -linked-Arab. The specific structure is the foliowing:3. The characteristic of MPS-1 was continuously observed by using the techinique of Raman, CD, SEM. The conformation could be changed by the factors of concentration, pH and complex compound according to the chart of CD. The result of X-ray and SEM indicated that the state structure of MPS-1 was noncrystal. The DSC analysis of it showed that the glass temperature of it is 41℃. The thermal analysis of it with TG also demonstrated that there appeared 3 weight-losses and three higher ratioes of weight loss were 55.3℃, 273.1 ℃, 415.2℃ respectively by DTG.4. Some of anti-tumor experiments were employed in order to test its biological activities. The MPS-1 showed strong inhibition activity in vitro on BGC-823, IC100>81.68%. In terms of anti-oxidation, MPS-1 had stronger clearing effects on OH , H2O2 and poorer capacity in scavenging O2- compared with MPS. As for scavenging hydroxgen radical, the ratio could be reach to 81.0% when the amount of it was 0.6mg ; As for scavenging peroxide hydroxgen, the ratio could be reach to 86.6% when the amount of it was 10.24mg.5 The chemical components and phytochemical properties of oil from Melia azedarach seeds were conducted by GC-MS. The main compounds are palmitic acid7.17%, stearic acid 4.16%, oleic acid 25.72%, linoleic acid 62.47%, arachidic acid 0.24%, eicosenoic acid 0.23%. The anounts of linoleic acid could be highly reached 62.47% among them. The oil had been further synthesized into conjugated linoleic acids (CLA) by alkali method. Response surface method (RSM) was applied to optimize the synthesis of it.The optimum condition was recommended to this model: 183.8℃, 2.86h and 6.43% alkali concentration. Besides, the axidative stability of this produt was made by adding tea polyphenol, which led to a higher inhibition on CLA, and the proper amount was 80ppm.
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