Synthesis of astaxanthin and its esters

Structure modification of astaxanthin exhibiting wide range of pharmacological properties opens the way to targeted synthesis of its peculiar semisynthetic derivatives. The selection of the optimal class of the modified astaxanthin should account for the fact that its esters with organic acids are the major bound form of its compounds in biological environment. Enzymatic catalysis with lipases of astaxanthin ester synthesis at low temperature allows to avoid the use of aggressive chemical agent. Esters of astaxanthin with benzoic, 4-methylbenzoic, nicotinic, phenylglycolic (mandelic), 2-hydroxybenzoic (salicylic) acids, and ibuprofen have been synthesized. The esterification reaction has been carried out in an anhydrous medium in the presence of a biocatalyst. Structure of the obtained compounds was confirmed by the data of 1H NMR spectroscopy and mass spectrometry. The stability of astaxanthin esters to environmental factors will solve the problems of its stabilization. The synthesis of astaxanthin esters in the presence of enzymes will reduce the amount of isomers in the target product and increase its safety and effectiveness. The main prospect of using astaxanthin esters is the targeted transport of pharmaceutical substances.