The Potential Use of Microalgal Carotenoids as Dietary Supplements and Natural Preservative Ingredients

Dunaliella salina has been selected as the most valuable microalgae for production of carotenoids as a source of natural pigment when grown under defined conditions. Compared with optimal conditions, D. salina contained higher amounts of total carotenoids (TCAR, 12.6%, dw)including -carotene (60.4%, of total carotenoids), astaxanthin (17.7%), zeaxanthin (13.4%), lutein (4.6%), and cryptoxanthin (3.9%)when grown under stress conditions. These TCAR showed greater in vitro antioxidant potential by inhibition of lipid peroxidation of rat liver microsomes induced by Fe++/ascorbate and Fe++/H2O2 model systems than butylated hydroxytoluene (BHT). The toxicological evaluation of D. salina functional ingredients as an antioxidant and natural food colorant was conducted, in which male albino rats were fed ad libitum for 6 weeks with one of the following diets: standard diet (S), S diets containing 0.5 g trans -carotene/kg diets (S + 0.5 C), S + 0.5 g D. salina carotenoids/kg diets (S + 0.5 DC), and S + 1.0 g D. salina carotenoids/kg diets (S + 1.0 DC). Generally, no mortality or treatment-related toxicological signs were observed in any of the rats during the 6 weeks of the experiment. The concentrations of glucose and glycogen in liver and glucose, total proteins, bilirubin, and creatinine as well as enzymes activities of aspartate (AST) and alanine aminotransferases (ALT), and alkaline phosphatase (ALP) in plasma were not significantly different from each other in all four diets. In contrast, the levels of total lipids and lipids components showed significant differences in all groups. Groups S + 0.5 C, S + 0.5 DC, and S + 1.0 DC showed a significant decrease in concentrations of total lipids, triglycerides, total cholesterol, and phospholipids in either plasma or hepatic tissues compared with S group. The results showed that D. salina carotenoids could be potentially rich sources of natural antioxidants and food colorants and have hypolipidemic and hypocholesterolemic properties.