Comparative evaluation of hepatoprotective activity of carotenoids of microalgae

The present study deals with evaluation of the hepatotoprotective activity of carotenoids from two well-known microalgae, Spirulina platensis and Dunaliella salina. Carotenoids were extracted in hexane:isopropyl alcohol (1:1 vol/vol) and fed orally in olive oil to Wistar albino rats at a dose of 100 µg/kg of body weight/day (in terms of carotenoids). The degree of hepatoprotection was measured by estimation of biochemical parameters like serum transaminases serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT), serum alkaline phosphatase, total albumin, and total protein. The results were compared with those for a control group, a CCl4-induced hepatic damage group, and a group treated with synthetic β-carotene (all-trans) at the same dose. The protein content of the CCl4-treated group, which received normal diet and a dose of toxin, showed a significant decrease, i.e., 3.92 mg/mL, whereas the protein levels were higher, i.e., 6.96 and 6.32 mg/mL, in the case of the Dunaliella and Spirulina, respectively, carotenoid-treated groups. The CCl4-treated group shown higher activity of transaminases (128.68 units/mL SGPT and 171.52 units/mL SGOT). However, the activity of SGPT was 62.83 units/mL for Dunaliella and 76.83 units/mL for Spirulina, i.e., carotenoids of Dunaliella showed a higher degree of protection. For serum alkaline phosphatase, the standard β-carotene value was 81.52 units/mL, compared with 84.46 units/mL for the CCl4-treated group; however, natural algal carotenoids yielded 38.45 units/mL (D. salina) and 44.73 units/mL (Spirulina). The total albumin value diminished with CCl4 treatment (2.46 mg/mL); the effect was highest for Dunaliella, followed by the Spirulina carotenoid-treated group. The results clearly indicate that carotenoids from Dunaliella possess better hepatoprotection compared with those from Spirulina. High-performance liquid chromatography of the carotenoids indicated that Spirulina contains only β-carotene and Dunaliella contains other carotenoids and xanthophyll. The increase in protection with Dunaliella indicates that mixed carotenoids exhibit better biological activity than β-carotene alone. The results of this study indicate that carotenoids obtained from an algal source have a higher antihepatotoxic effect, compared with synthetic β-carotene and with β-carotene alone from a natural source