Chromatographic Separation and Purification of trans-Astaxanthin from the Extracts of Haematococcus pluvialis

A gradient reversed-phase HPLC method was developed for the separation of astaxanthin esters and the isomers of astaxanthin from the unsaponified and saponified pigment extracts of the microalga Haematococcus pluvialis . Four kinds of isomers of astaxanthin and astaxanthin esters, (3 S,3‘ S )- trans -astaxanthin, (3 S,3‘ S )-9- cis -astaxanthin, (3 S,3‘ S )-13- cis -astaxanthin, (3 R,3‘ R )- trans -astaxanthin, and their esters, were separated and identified. A small amount of (3 S,3‘ S )-15- cis -astaxanthin was also detected from the saponified extract. In addition, a chromatographic purification method was established for the preparation of natural trans -astaxanthin from the saponified extract of H. pluvialis . With this method, 3.7 mg of astaxanthin was isolated from 1 g of dry biomass of H. pluvialis . The purified astaxanthin contained approximately 97.7% trans -astaxanthin, 1.1% cis -astaxanthin, and 1.2% impurity. Keywords: Astaxanthin; astaxanthin esters; purification; carotenoids; Haematococcus pluvialis; HPLC