出版社：American Society for Biochemistry and Molecular Biology
摘要：Some oxidized forms of cholesterol (oxysterols) are thought to be atherogenic and cytotoxic. Because plant sterols are structurally related to cholesterol, we examined whether oxidized plant sterols (oxyphytosterols) could be identified in human serum and soy-based lipid emulsions. We first prepared both deuterated and nondeuterated reference compounds. We then analyzed by gas-liquid chromatography-mass spectrometry the oxyphytosterol concentrations in serum from patients with phytosterolemia or cerebrotendinous xanthomatosis, in a pool serum and in two lipid emulsions. 7-Ketositosterol, 7β-hydroxysitosterol, 5α, 6α-epoxysitosterol, 3β,5α,6β-sitostanetriol, and probably also 7α-hydroxysitosterol were present in markedly elevated concentrations in serum from phytosterolemic patients only. Also, campesterol oxidation products such as 7α-hydroxycampesterol and 7β-hydroxycampesterol were found. Interestingly, sitosterol was oxidized for approximately 1.4% in phytosterolemic serum, which is rather high compared with the approximate 0.01% oxidatively modified cholesterol normally seen in human serum. The same oxyphytosterols were also found in two lipid emulsions in which the ratio of oxidized sitosterol to sitosterol varied between 0.038 and 0.041. In conclusion, we have shown that oxidized forms of plant sterols are present in serum from phytosterolemic patients and two frequently used soy-based lipid emulsions. Currently, it is unknown whether oxyphytosterols affect health, as has been suggested for oxysterols. However, 7β-hydroxycholesterol may be one of the more harmful oxysterols, and both sitosterol and campesterol were oxidized into 7β-hydroxysitosterol and 7β-hydroxycampesterol. The relevance of these findings therefore deserves further exploration. —Plat, J., H. Brzezinka, D. Lütjohann, R. P. Mensink, and K. von Bergmann. Oxidized plant sterols in human serum and lipid infusions as measured by combined gas-liquid chromatography-mass spectrometry. J. Lipid Res. 2001. 42: 2030–2038.
