Biochemistry of Haematococcus

Freshwater, unicellular green microalga called Haematococcus pluvialis (Chlorophyta) has a complicated life cycle. Haematococcus is the only species that produces astaxanthin from a variety of natural sources (pink carotenoid). Due to the increased carotenoid deposition caused by stress, the manufacture of astaxanthin is typically followed by the transition of ovoid green vegetative cells into red cysts. Compared to other carotenoids and vitamin E, the antioxidant activity and efficiency of astaxanthin, a pigment derived from carotenoids, is significantly higher. Astaxanthin is produced by the enzyme astaxanthin synthase (CrtS) and the cytochrome P450, CrtR. Similar to other carotenoids, astaxanthin has a high antioxidant effect by scavenging free radicals, reducing lipid peroxidation, boosting immune system performance, and controlling gene expression. Hepatic stellate cells are inhibited from activating by astaxanthin, which inhibits them from changing. Astaxanthin inhibits transforming growth factor (TGF-1)-induced pro-fibrotic gene expression and hepatic fibrosis by preventing the activation of hepatic stellate cells. In mice fed high fat-high fructose diets, astaxanthin improves glucose metabolism, decreases expression of hepatocellular endoplasmic reticulum stress proteins, and reduces hepatocellular lipid accumulation. Astaxanthin has a weak inhibitory effect on human CYP2C19 but not on the other eight CYP activities and is not thought to be a significant cause of altered CYP activity.