皂化处理对中华管鞭虾虾青素提取物的虾青素组成和体外抗氧化性的影响

采用低温皂化中华管鞭虾的虾青素提取物，比较皂化前后虾青素总浓度、抗氧化活性、游离型和酯型虾青素相对浓度以及虾青素光学异构体组成变化。结果表明:适当皂化处理可显著提高虾青素提取物的总虾青素浓度，皂化时间对虾青素提取物的抗氧性有显著影响（P<0.05），其中皂化2 h时对DPPH自由基清除率达到25.85%，显著高于未皂化的15.16%，虾青素提取物对羟自由基和总抗氧化能力则在皂化6 h时分别达到3.17和0.62 U/μg。高效液相分析结果显示:皂化2 h时虾青素提取物中酯型虾青素已经大部分转化为游离型虾青素，而延长皂化时间会造成游离型虾青素发生不同程度的降解。未皂化的虾青素提取物光学异构体以3S, 3′S型为主，经过皂化处理后光学异构体3S, 3′S:3S, 3′R:3R, 3′R比值保持在2.4:1.5~1.7:1.0之间。此外，研究还发现皂化后虾青素提取物中三种光学异构体含量均与羟自由基清除能力呈现较好的线性相关性（R>0.784）。综上，皂化后中华管鞭虾的虾青素提取物抗氧化性变化与游离型和酯型虾青素组成变化及光学异构体组成变化有关。

Effects of Saponification on Astaxanthin Composition and in Vitro Antioxidant Activity of Astaxanthin Extract from Penaeus sinensis (Solenocera crassicornis)

In this study, the low temperature saponification treatment was used to hydrolyze the astaxanthin (Asta) extracts of Penaeus sinensis. Further, the changes of total Asta concentration, antioxidant activity, free form and ester form of Asta and its optical isomerswere compared before and after saponification. The results showed that proper saponification treatment significantly increased the total Asta concentration of the extracts. Moreover, the saponification time played crucial roles on the in vitro antioxidant activity of the Asta extracts (P<0.05). The scavenging activity of the Asta extract on DPPH free radical was 28.85% after 2 h of saponification, significantly higher than 15.16% of un-saponified. The activity of scavenging hydroxyl free radicals and total antioxidant capacitywere increased to 3.17, 0.62 U/μg, respectively, after 6 h of saponification.The results of HPLC analysis demonstrated that most of Asta esters were transferred into free Asta after 2 h of saponification. Further, the free Asta producedwas destroyed in some degree when exposed to long time saponification. The optical isomer in the un-saponified Asta extracts was mainly composed of 3S, 3′S. In the process of saponification, the relative content ratio of the relative content ratio of 3S, 3′S:3S, 3′R:3R, 3′R was maintained between 2.4:1.5~1.7:1.0. Further, the three optical Astaisomers in saponification solutions had high linear correlations with their scavenging activities on hydroxyl free radicals (R>0.784). In conclusion, the changes of antioxidant activity of astaxanthin extracts from the saponified Penaeus sinensis were related to the changes of free and ester astaxanthin composition and optical isomer composition.