Biocatalytic Synthesis Of Nitro-unsaturated Fatty Acids And Their Derivatives

Nitro-unsaturated fatty acids are a kind of unsaturated fatty acids, which have a nitro group after nitrification. They have high chemical reactivity and present a profound biological application. It has been proved that nitro fatty acids such as nitro oleic acid and nitro linoleic acid present in plasma, urine, tissues and cell membranes. Nitro oleic acid and nitro linoleic acid exist in a concentration over 1μM in healthy humans. They play an important role in the regulation of the inflammatory response and play as activator of PPAR receptors. They naturally exist in the body and no obvious side effects, with a wide range of biological activity. If you can come up a certain method to synthesis nitro-unsaturated fatty acids efficiently in vitro, they will have a broader clinical exploitation. The oleic acid and methyl oleate were treated as the main objects of the research. We have synthetised nitro oleic acid and nitro methyl ester by biological methods, which was compared with chemical methods in this paper.We choose Aspergillus oryzae which generated peroxidase preserved in the laboratory. By the way of the liquid fermentation, peroxidase was extracted from the fermentation liquor. After preliminary purification, enzyme activity was 4.50 U/mL. Then, we investigated the stability of peroxidase activity for pH and temperature, respectively. The results showed that in the conditions of pH=7 and 45 ℃, the stability of the enzyme activity was relatively good.The nitro oleic acid got by chemical synthesis method yielded 58.9%. The proportion of the primary product and by-product was 1:4. Then combined with biocatalytic synthesis, a 1:1 ratio of the two products was reached. And then we sythetised nitrated methy oleate chemically in the same, the yield was 42%, the ratio of the two products was 1:2. (Main products were 14.3% yield; the by-products were 26.9% yield.) And then nitrated methy oleate generated by biocatalytic synthesis was 3.5% yield. And the product was very pure without by-products. After separation and purification, the products were characterized as nitro-unsaturated fatty by IR, NMR, LC-MS and GC-MS techniques. And furthermore, the purity of nitro-methyl ester by biocatalytic synthesis was 98%.This experiment proved that peroxidase played a critical role in the generation of unsaturated fatty nitro process, which is possible to suppress the production of by- products. Although obviously limited in the production scop, and it was not significant to the generation of O A-NO2, the character of oleic acid and methyl ester is different, the reasons have yet to be explored.