Takaichi Shinichi, Matsui Kumi, Nakamura Masahisa, Muramatsu Mizuho, Hanada Satoshi
Biological Laboratory, Nippon Medical School, Kosugi-cho, Nakahara, Kawasaki 211-0063, Japan.
Comp Biochem Physiol B Biochem Mol Biol. 2003 Oct;136(2):317-22. doi: 10.1016/s1096-4959(03)00209-4.
Krill is a major source of astaxanthin, which has strong antioxidant activity. Fractions with astaxanthin monoesters and diesters of Antarctic krill Euphausia superba were isolated. Astaxanthin esters were separated by C18-HPLC depending on the number of carbons and double bonds of esterified fatty acid(s). Small amounts of other lipids remained in the samples, but relative molecular masses of carotenoid esters could be measured by field desorption mass spectrometry without fragmentation and interference from contaminant lipids. The fatty acids were determined by calculation of difference between astaxanthin and astaxanthin esters. Only five kinds of fatty acids, dodecanoate, tetradecanoate, hexadecanoate, hexadecenoate and octadecenoate, were detected. Fast atom bombardment mass spectrometry and secondary ion mass spectrometry showed similar spectra. The fatty acid composition in astaxanthin esters was different from those in krill lipids. Therefore, determination of fatty acids in carotenoid esters by a combination of HPLC elution profile and mild mass spectrometry is found to be a useful tool.
磷虾是虾青素的主要来源，虾青素具有很强的抗氧化活性。分离出了南极磷虾（Euphausia superba）中虾青素单酯和二酯的组分。根据酯化脂肪酸的碳数和双键数量，通过C18-HPLC分离虾青素酯。样品中残留少量其他脂质，但通过场解吸质谱法可测量类胡萝卜素酯的相对分子质量，而不会受到污染物脂质的碎片化和干扰。通过计算虾青素和虾青素酯之间的差异来测定脂肪酸。仅检测到五种脂肪酸，即十二烷酸、十四烷酸、十六烷酸、十六碳烯酸和十八碳烯酸。快原子轰击质谱法和二次离子质谱法显示出相似的光谱。虾青素酯中的脂肪酸组成与磷虾脂质中的不同。因此，发现通过HPLC洗脱曲线和温和质谱法相结合来测定类胡萝卜素酯中的脂肪酸是一种有用的工具。
