Yasugi E, Saito E, Kasama T, Kojima H, Yamakawa T
J Biochem. 1982 Apr;91(4):1121-7. doi: 10.1093/oxfordjournals.jbchem.a133794.
Four glycolipids (Fr. I, II, III, and IV) were isolated from whale brain and three (Fr. I, II, and III) of them were demonstrated to be galactosyl ceramide combined with fatty acid by ester linkage. Fr. IV was shown to be a monoalkyl monoacyl galactosyl glycerol. For determining the substituted position of the acyl group on the galactose moiety, free hydroxyl groups of ester cerebrosides were protected with dihydropyran, deacylated by mild alkali treatment, and then subjected to permethylation. Finally, the methylated galactitol acetates obtained by hydrolysis and reduction were detected by gas chromatography and identified by gas chromatography-mass spectrometry. By this procedure, Fr. I was shown to be an acyl ester of kerasine, with the ester group at the 6-position of galactose. Fr. II and III were demonstrated to be acyl esters of phrenosine, in which the acyl groups were attached to the 6- and 2-position of the galactose, respectively. While the ester-linked acyl group of Fr. I, II, and III was composed of only normal fatty acids, predominantly palmitic acid, and the amide-linked fatty acids showed a heterogeneous composition of normal and hydroxy fatty acids, C16 to C24.
从鲸脑中分离出四种糖脂（馏分I、II、III和IV），其中三种（馏分I、II和III）被证明是通过酯键与脂肪酸结合的半乳糖神经酰胺。馏分IV被证明是单烷基单酰基半乳糖甘油。为了确定酰基在半乳糖部分的取代位置，酯型脑苷脂的游离羟基用二氢吡喃保护，通过温和的碱处理脱酰，然后进行全甲基化。最后，通过气相色谱检测水解和还原后得到的甲基化半乳糖醇乙酸酯，并通过气相色谱-质谱联用进行鉴定。通过该方法，馏分I被证明是鲨肝醇的酰基酯，酯基位于半乳糖的6位。馏分II和III被证明是羟脑苷脂的酰基酯，其中酰基分别连接在半乳糖的6位和2位。虽然馏分I、II和III的酯键连接的酰基仅由正常脂肪酸组成，主要是棕榈酸，而酰胺键连接的脂肪酸显示出正常脂肪酸和羟基脂肪酸的异质组成，碳链长度为C₁₆至C₂₄。
