Extraction And Characterization Of Anti-ultraviolet Substances From Porphyra Yezoensis

Mycosporine-like amino acids (MAAs) is a kind of specific compound which exists in algae and bacteria. It is naturally high-efficient ultra-violet absorber. Because of the depletion of the ozone layer, the amount of the ultraviolet radiation that reaches the earth's surface is increasing. The excessive amount of ultraviolet radiation may cause great harm to animals and plants in the earth. The long-term use of artificially synthesized ultra-violet absorber has some risk. Therefore, the study on natural high-efficient ultra-violet absorber is becoming a hotspot currently. China has a vast territory and a long coastline. The annual output of the algae is millions of tons, providing raw materials for the research of ultra-violet absorber.In this paper with Fujian Porphyra yezoensis as material, (1)confirmed the classes of the MAAs compounds in Fujian Porphyra yezoensis by analyzing the extracting solution of Porphyra yezoensis, using liquid chromatogram and mass spectrometry; (2)optimized the extraction process of the MAAs compounds by single factor and orthogonal experiments; (3)improved the purity of MAAs compounds in the samples by resin separation technology;(4)determined the anti-oxidation of the MAAs compounds in vitro systems to study the relations between the absorbing ultra-violet function and anti-oxidation in MAAs compounds.The results were listed as below:1. Ultraviolet spectrum and mass spectrometry determination of maximum ultraviolet absorption peak (334nm) of the MAAs compounds in Fujian Porphyra yezoensis, and the molecular weight of Porphyra-334 and shinorine are 346 and 332,respectively.2. By single factor and orthogonal experiments, the optimum extraction process is determined as:the initial pH value of water extracts is 2.0, the extraction time period is 1.5h, the extraction temperature is 45℃and the ratio of material and liquid is 1 to 8. Under the optimum extraction process, the extraction ratio of porphyra-334 and shinorine are 5.124mg/g and 3.941mg/g, respectively.3.The purification process of MAAs compounds includes the following steps. SA-2 resin, PH 7 adsorption solution, and the HPLC system consisted of flow rate:1.0 mL/min,25℃. Gradient elution with pH values 4 and 2 HC1,50℃, and the volume of eluent to 3BV to carry out elution with the flow rate 1.5ml/min by D296 resin, removing excess the HCl solution. Liquid was collected under vacuum freeze drying, the purity and yield of the samples were 82.4% and 94.1%.4. The reducing power of MAAs compounds and their power of eliminating DPPH free redical is are in linear relationship with their concentration. Their reducing power and power of eliminating DPPH free redical are relatively weak, which are not as great as those of Vc and sodium erythorbate. MAAS compounds'ability of eliminating superoxide anion is in linear relationship with their concentration. It's IC50 is 24.87μg/ml, which is lower than the IC50 of Vc 37.15μg/ml and the IC50 of sodium erythorbate 47.64μg/ml. This shows the excellent ability of eliminating superoxide anion of the MAAs compounds. In the extent of low concentration, MAAs compounds'ability of eliminating hydroxyl radical is in linear relationship with their concentration. And their elimination ability is between that of Vc and sodium erythorbate. In the extent of high concentration, MAAs compounds'ability of eliminating hydroxyl radical is in dose-response relationship with their concentration and better than Vc and sodium erythorbate. This proves MAAs compounds'better ability of eliminating hydroxyl radical. MAAs compounds'ability of inhibiting lipid oxidation has positive correlation with their concentration. In the extent of low concentration, the ability increases linearly with concentration falling and the ability of inhibiting lipid oxidation is better in the extent of low concentration. MAAs compounds' ability of inhibiting lipid oxidation is close to that of Propyl p-Hydroxybenzoate and worse than that of PG.The current researches on MAAs compounds are mainly from the aspects of their physiological function, biosynthetic mechanisms, environmental factors'influence on MAAs, the induction of ultraviolet rays to MAAs and the distribution of MAAs. The research on the application of these kinds of materials which can absorb ultraviolet rays is still at the first stage and the research is limited in scale and depth. This paper is aimed at enriching the research fields of MAAs compounds and providing scientific evidences for the industrialized application of MAAs compounds.