本文調查研究了蝦青素單酯和二酯及總類胡蘿卜素的抗癌作用以及蝦青素對紫外7,12-二甲基苯并蒽誘導的小鼠皮膚癌的抵抗作用。當蝦青素含量為200微克/千克（小鼠體重）時，蝦青素單酯和二酯能夠分別降低96% 和88%紫外7,12-二甲基苯并蒽誘導腫瘤的發生率，而蝦青素和總類胡蘿卜素可以降低66%及85%。已知紫外7,12-二甲基苯并蒽可以產生高濃度自由基及酪氨酸酶，從而導致皮膚色素沉著及腫瘤發生。令人驚奇的是蝦青素單酯和二酯可以增加7倍左右的酪氨酸酶，降低10倍抗氧化水平，與之相對的是蝦青素和總類胡蘿卜素增加1.4倍左右的酪氨酸酶，降低2.2倍抗氧化水平。這些結果以及蝦青素單酯和二酯處理可使動物血清中視黃醇達到72 ng/mL，蝦青素處理可使動物血清中視黃醇達到58 ng/mL一起表明蝦青素單酯和二酯在抗癌方面更有效。
Effective inhibition of skin cancer, tyrosinase, and antioxidative properties by astaxanthin and astaxanthin esters from the green alga Haematococcus pluvialis
Astaxanthin mono-(AXME) and diesters(AXDE) were characterized and examined for anticancer potency with total carotenoids(TC) and astaxanthin(AX) against UV-7,12-dimethylbenz(a)anthracene (DMBA)-induced skin cancer model in rat. At 200 μg/kg bw, AXDE and AXME reduced UV-DMBA-induced tumor incidences up to 96 and 88%, respectively, when compared to AX (66%) and TC (85%). UV-DMBA has been known to generate high levels of free radicals and tyrosinase enzyme, leading to characteristic symptoms of skin pigmentation and tumor initiation. Intriguingly, ~7-fold increase in tyrosinase and 10-fold decrease in antioxidant levels were normalized by AXDE and AXME as opposed to only ~1.4-2.2-fold by AX and TC, respectively. This result together with the appearance of 72 and 58 ng/mL of retinol in the serum of respective AXE-treated (AXDE + AXME) and AX-treated animals suggested that better anticancer potency of AXEs could be due to increased bioavailability.
J Agric Food Chem. 2013, 61(16):3842-3851.
Rao AR, Sindhuja HN, Dharmesh SM, Sankar KU, Sarada R, Ravishankar GA.
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