Assessment and Comparison of in vitro Immunoregulatory Activity of Three Astaxanthin Stereoisomers

In recent years,the immune-modulatory role of all-trans astaxanthin from different pigment sources has been studied.It was reported that all-trans astaxanthin might exist as three stereoisomers,and the composition of all-trans stereoisomers in natural materials differs from that of synthetic products.However,the different biological effects of various all-trans stereoisomers still remain unclear.In the present study,we evaluated the bioactivity of three astaxanthin stereoisomers,(3S,3'S)-trans-,(3R,3'R)-transand meso-trans-astaxanthin,in regulating cell-mediated immune response using mice lymphocytes and peritoneal exudates cells(PECs) systems.After the treatment with three astaxanthin stereoisomers(20 μmol L-1),the lymphocyte proliferation capacity,neutral red phagocytosis of PECs and natural killer(NK) cell cytotoxic activity were comparatively assessed.The results showed that all three astaxanthin stereoisomers significantly promoted lymphocyte proliferation,phagocytic capacity of PECs,and cytotoxic activity of NK cells.Moreover,the(3S,3'S)-trans-astaxanthin exhibited a much higher response than others.

Cell cycles and proliferation patterns in Haematococcus pluvialis

Most studies on Haematococcus pluvialis have been focused on cell growth and astaxanthin accumulation;far less attention has been paid to cell cycles and proliferation patterns.The purpose of this study was to clarify cell cycles and proliferation patterns in H.pluvialis microscopically using a camera and video recorder system.The complicated life history of H.pluvial i s can be divided into two stages:the motile stage and the non-motile stage.All the cells can be classifi ed into forms as follows:motile cell,nonmotile cell,zoospore and aplanospore.The main cell proliferation,both in the motile phase and non-motile phase in H.pluvialis,is by asexual reproduction.Under normal growth conditions,a motile cell usually produces two,sometimes four,and exceptionally eight zoospores.Under unfavorable conditions,the motile cell loses its fl agella and transforms into a non-motile cell,and the non-motile cell usually produces 2,4 or 8 aplanospores,and occasionally 20–32 aplanospores,which further develop into non-motile cells.Under suitable conditions,the non-motile cell is also able to release zoospores.The larger non-motile cells produce more than 16 zoospores,and the smaller ones produce 4 or 8 zoospores.Vegetative reproduction is by direct cell division in the motile phase and by occasional cell budding in the non-motile phase.There is,as yet,no convincing direct evidence for sexual reproduction.