葉黃素已被發現於眼睛水晶體中，其結構中含有多個共軛雙鍵，於人類視網膜裡有過濾藍光之作用，以保護眼睛免受到光之傷害。葉黃素亦具抗氧化作用，可以抑制光化學作用後所產生的活性氧類（Reactive oxygen species, ROS），可有效預防白內障以及降低黃斑部病變發生，近年來已被大量地推廣使用。相對於目前商業化葉黃素之主要來源-金盞花(marigold flower)，利用微藻(microalga)生產葉黃素有許多優點，如微藻有較高之生長速率亦無季節性之限制，且其養殖之人力需求較低等。
本研究致力於利用微藻(Chlorella Sorokiniana)萃取與純化葉黃素，並利用高效液相層析儀(HPLC, high performance liquid chromatography）分析其不同萃取階段及不同條件之葉黃素含量，發展兩種萃取純化方法，將二氯甲烷粗萃物經過管柱層析純化(方法A)，得到的葉黃素純度極高(90%以上)，但是其產率非常低(0.577%)，而未經過管柱層析，以85%乙醇溶液萃取純化(方法B)，其產率較高(50.4%)，但是葉黃素純度較低(76.85%)。由DPPH自由基清除能力實驗中顯示方法A萃取純化之葉黃素有較佳的抗氧化能力，故以純度90%以上之葉黃素(方法A)添加入水晶體蛋白中，分別進行: (1)利用ascorbate-FeCl3-EDTA-H2O2的氧化系統氧化水晶體蛋白，利用紫外光/可見光光譜儀 (UV-Vis Spectrophotomer)檢測蛋白質氧化集結的混濁程度以及葉黃素捕捉過氧化氫之能力 (2)利用UVA照射水晶體蛋白使其產生光氧化反應，並利用Trp螢光光譜及ANS螢光光譜，探討蛋白質Trp微環境變化與表面疏水性暴露的改變。
實驗結果顯示未添加葉黃素的水晶體蛋白經氧化系統氧化後，隨著氧化時間增加，其混濁度有增加的趨勢，而添加葉黃素的水晶體蛋白隨著葉黃素的濃度增加，其混濁度明顯下降且捕捉過氧化氫的能力也有增強的現象；Trp螢光光譜及ANS螢光光譜皆顯示隨著照光時間增加，未添加葉黃素的水晶體蛋白結構產生了明顯的變化甚至遭受破壞而變性，而添加葉黃素的水晶體蛋白結構變化有明顯趨緩的現象。本研究更進一步支持對於保護水晶體蛋白免受氧化壓力的破壞以及抑制紫外線照射所造成的影響，葉黃素扮演了非常重要的角色。

A method for the extraction and purification of lutein from lyophilized microalgae (Chlorella Sorokiniana) powder was employed. Sponification using 10 M KOH solution containing 2.5% ascorbic acid and extraction using DCM, followed by removing the fat-soluble ingredients with hexane, and finally using flash column chromatography eluted with hexane/ethyl acetate (20:1~1:1; v/v) to obtain lutein with 92.77% purity and 0.577% yield. Another method using recrystallization in 85% ethanol aqueous solution to purify the lutein instead of using flash column chromatography was employed. This was a quick and easy way, however, the purity was 76.85% and 5.04% yield.
Lutein plays a protective role in quenching of reactive oxygen species during oxidative stress conditions in lens. H2O2 is one of the physiologically relevant oxidants in the lens and aqueous humor, UVA also cause the phototoxic damage of lens through photo-oxidation to produce active species. Oxidative stress is an initiating factor for the development of cataract and describes the events leading to lens opacification and the conformational change of lens crystalline residues. Therefore, in this study, we focus on the effects of lutein from microalgae C. Sorokiniana on the inhibition of oxidative stress under oxidation with ascorbate–FeCl3–EDTA–H2O2 by antioxidant activity assay and the prevention of lens crystallins from UV damage employing by tryptophan and ANS fluorescence to investigate the UV induced structural change of lens α-/γ-crystallin and the hydrophobic exposure. According to the results from the present study, lutein from microalgae C. Sorokiniana was found to be an effective antioxidant to protect lens crystallins from damage in in vitro assay.

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