Extraction And Antioxidative Activity Of Astaxanthin From Haematococcus Pluvialis

Astaxanthin, 3,3'-dihydroxy-4,4'-dione-β,β'-carotene, is a strong antioxidant, and its oxidative activity is 10 times more thanβ-carotene, and 500 times greater than vitamin E, so it is called"super vitamin E". In addition, it also has anti-tumor and immunity enhancement activities. In aquaculture, it can be used in food additives and other industries.Currently, astaxanthin are mainly produced from processing wastes of the crustaceans and chemical synthesis. In this paper, the author investigated the extraction process of astaxanthin in the Haematococcus pluvialis, and established a qualitative analysis by high performance liquid chromatography (HPLC) and quantitative determination by spectrophotometry. Pretreatment was also conducted to improve the extraction rate of free astaxanthin in the crude extracts. In addition, the paper also established a determination model of antioxidative activity which the olive oil was substrate. Antioxidative activity of free astaxanthin and astaxanthin esters of fatty acids was compared with ascorbic acid via the above model.According to the results of extracting astaxanthin, extraction rate increased as the ratio of liquid rising till it is 20:1 (v/w) when the extraction close to the highest value. Later, the extraction volume tends to balance; twice extraction with organic solvent extraction can achieve the total content of more than 90%, so the twice extraction can be used in the actual production. Different solvents have no significant difference in chemical composition of the extraction products, but the proportion of each component concentration was different with each other. Dichloromethane extracts had the highest absorbance under 480 nm and lower absorbance under 663 nm and 645 nm, indicating that the solvents was highly efficient for extraction of astaxanthin, while the ethanol had a slightly less extraction rate than dichloromethane, but its advantages of low toxicity and reduction of Pb content rendered ethanol a more appropriate solvent for extraction of astaxanthin.Meanwhile, the saponification of the ethanol extracts from Haematococcus pluvialis algae was carried on, because chlorophyll is an ester and astaxanthin in the algae exists as esters formed with fatty acids. Both of them may occur saponification reaction in the alkali. Thus saponification can eliminate chlorophyll, as well as getting free astaxanthin. Orthogonal experimental results showed that the base would undermine the structure of astaxanthin and the saponification reaction may oxidize the astaxanthin, the optimum experimental conditions obtained only 0.1% dry weight of free astaxanthin, and some oxidation products of astaxanthin also appeared. Therefore, saponification conditions can be further optimized to reduce the loss of astaxanthin.This paper also established an antioxidative activity screening model using the olive oil as substrate, and the antioxidative activity of ethanol extract of Haematococcus pluvialis and free astaxanthin was investigated based on this model. The results show that astaxanthin can slow down the oxidation of fatty acids in olive oil, and hence, it can be concluded that astaxanthin is a strong antioxidant.