Characterisation of esterified secondary carotenoids and of their isomers in green algae: a HPLC approach

Under certain environmental conditions, green algae can produce a variety ofsecondary, non-photosynthetic carotenoids which are predominantly esterified with fattyacids. Our HPLC method is designed to characterise such carotenoid ester patterns with-out the need of saponification, what may cause artefacts or losses. The individual chro-matogram of a species can help to typify a green alga on a chemotaxonomical level. Ademonstration of the performance is given with two species whose cyst stages are knownfor a large production of secondary carotenoids, Chlamydomonas nivalis and Haemato-coccus pluvialis . The separation of carotenoid isomers is shown with the example of as-taxanthin. Both algae accumulate, besides the standard type all- trans astaxanthin, alsosignificant amounts of a cis-isomer (13 Z -astaxanthin). The latter has an additional spec-tral absorption in the near UV-region (about 375 nm) and thus may play a role in avoid-ance of UV-irradiance stress which frequently occurs in the natural habitats of these al-gae. Atechnique to ensure an optimum-yield, artefact-free opening of algal cysts is alsopresented.