| Flavonoids is a class of natural products which distributed widely in plants and has been used in producing natural sweetener, antioxidants, pigments, pharmaceuticals, pesticides and other products. It plays an important role in the health of human and plant growth, development, blossom and bearing fruit, etc. With the deepening research of the flavonoids, the medicinal value of flavonoids was receiving people’s attention greatly, thus the study of flavonoids has been the research hot this years. Modern research had proved that the leaf, flower, fruit, and root bark of Salvinia natans contained a variety of flavones and isoflavones, such as quercetin, kaempferol, isorhamnetin. Commonly, the effective components in the flower, leaf, fruit of Salvinia natans were existed in the form of glycoside, while in relatively hard tissues such as root and skin, the effective components of Salvinia natans were existed in the form of aglycone. At present, the flower、fruit of Salvinia natans and their extractives were mostly used as drugs, but the report on reasonable using of the leaves of Salvinia natans was rare, the method of handling the leaves of salvinia natans was simple, usually by centralized burning, which lead to a greater degree of environment pollution and resource wasting. Therefore, how to make full uwe of the leaves of salvinia natans, was the outstanding problem to the scientific researchers.This work focused on the extraction of flavonoids from the leaves of salvinia natans by using ethanol immersion extraction method, both single factor experiment and the response surface method were adopted to optimize the extraction conditions. On this basis, the separation and purification of flavonoids in Salvinia natans could be carried out by MAR mixed bed technology. With the ultraviolet spectrophotometer as detection means, adsorption quantity and rate, the desorption quantity and rate as the indexes, the static adsorption/desorption experiments were performed on flavonoids of Salvinia natans by MAR mixed bed. At the same time, the flavonoids of Salvinia natans in different periods were studied. The results are as follows:(1) The flavonoids in salvinia natans were extracted by using ethanol immersion extraction method, and the material liquid ratio, extraction temperature, pH value, the influence of ethanol volume fraction and other conditions on the extraction yield were systematically studied. The results showed that the optimum conditions were:the mesh of salvinia natans was60, the ratio of material to solvent was1:30, the pH value of the solvent was7, the extraction temperature was40℃, the extraction time was20h and the extraction times was3. Under the optimum conditions, the extraction rate and purity of the flavonoids were75.87%and17.67%, respectively.(2) The adsorption/desorption experiments were carried out by using26sorts of MARs on the extracted flavonoids and the flavonoids content in adsorption residual liquor and desorption solution was determined by using the ultraviolet spectrophotometer. On the basis of single MAR experiments, two, three and four kinds of MAR mixed bed were screened and the optimal combination of MAR mixed bed LS-10+LS-17+LS-5was obtained. Its mass ratio wasmLs-10: mLs-17: mLS-5=3:2:1. The adsorption mechanism was studied by the different models and the adsorption/desorption process conditions, such as adsorption volume, temperature, pH, desorption temperature, pH value of desorption solutions were optimized. Under the optimum process conditions, the adsorption rate of MAR mixed bed LS-809-K+LS-600+LX-38to the flavonoids was63.65%, the desorption rate was87.31%, the adsorbing capacity was9.113mg/g, the desorption capacity was7.956mg/g and the purity was58.17%.(3) On the basis of previous work, with rutin as the standard, the content of total flavonoids in different growth periods was studied by using the ultraviolet spectrophotometric. The relations between the content of flavonoids in salvinia natans and growth time were discussed. The results showed that the content of flavonoids in May was relatively higher than other months, and the content of flavonoids in the sunny slope was higher than the nightside under the same harvest time. The rule of the content of flavonoids in salvinia natans with the season variety was preliminary studied and the theoretical basis of picking salvinia natans at the best time was found. At the same time, the research also provided a basis for the effective utilization salvinia natans. |
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