The ketocarotenoid astaxanthin can be found in the microalgae Haematococcus pluvialis, Chlorella zofingiensis, and Chlorococcum sp., and the red yeast Phaffia rhodozyma. The microalga H. pluvialis has the highest capacity to accumulate astaxanthin up to 4-5% of cell dry weight. Astaxanthin has been attributed with extraordinary potential for protecting the organism against a wide range of diseases, and has considerable potential and promising applications in human health. Numerous studies have shown that astaxanthin has potential health-promoting effects in the prevention and treatment of various diseases, such as cancers, chronic inflammatory diseases, metabolic syndrome, diabetes, diabetic nephropathy, cardiovascular diseases, gastrointestinal diseases, liver diseases, neurodegenerative diseases, eye diseases, skin diseases, exercise-induced fatigue, male infertility, and HgCl₂-induced acute renal failure. In this article, the currently available scientific literature regarding the most significant activities of astaxanthin is reviewed.

An oil-producing microalga SP-01 belonging to the genus Scenedesmus was shown to be able to grow on a media containing 5 to 30 g L -1 NaCl. Under mixotrophic condition, the maximum cell dry weight of 3.1 g L -1 and specific growth rate of 0.034 h -1 were obtained at 0.5 g L -1 NaNO 3 and 6 g L -1 acetate. The effects of salinity on the biomass, lipid, and carotenoid productions of the alga SP-01 in mixotrophic mode were investigated. The biomass productivity increased with increasing NaNO 3 concentrations, and addition of NaCl resulted in a higher biomass while NaNO 3 was present. The maximum lipid content was obtained while no NaNO 3 and NaCl was added, and the lipid content decreased with increasing NaNO 3 concentrations or addition of NaCl. The maximum lipid productivities of 67.44 to 68.44 mg L -1 day -1 were obtained while NaNO 3 and NaCl were not added or while 20 g L -1 NaCl and 0.13 g L -1 NaNO 3 were added. The algal lipid was mainly composed of C16 and C18 fatty acids accounting for more than 90% of total fatty acids. Furthermore, lutein and astaxanthin were the main carotenoids.