Mass Spectrometry Characterization of the 5-, 7-, and 7src=

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• 作者：Renzo Bortolomeazzi ; Michela De Zan ; Lorena Pizzale ; and Lanfranco S. Conte
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：1999
• 出版时间：August 1999
• 年：1999
• 卷：47
• 期：8
• 页码：3069 - 3074
• 全文大小：80K
• 年卷期：v.47,no.8(August 1999)
• ISSN：1520-5118

文摘

The 5SRC="/images/gifchars/alpha.gif" BORDER=0>-hydroperoxides of s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-sitosterol, campesterol, stigmasterol, and brassicasterol were obtainedby photooxidation of the respective sterols in pyridine in the presence of hematoporphyrine assensitizer. The reduction of the hydroperoxides gives the corresponding 5s/gifchars/alpha.gif" BORDER=0>-hydroxy derivatives.The 7s/gifchars/alpha.gif" BORDER=0>- and 7s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-hydroperoxides of the sterols were obtained by allowing an aliquot of the5s/gifchars/alpha.gif" BORDER=0>-hydroperoxides to isomerize to 7s/gifchars/alpha.gif" BORDER=0>-hydroperoxides, which in turn epimerize to 7s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-hydroperoxides.The reduction gave the corresponding 7s/gifchars/alpha.gif" BORDER=0>- and 7s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-hydroxy derivatives. The 5s/gifchars/alpha.gif" BORDER=0>-, 7s/gifchars/alpha.gif" BORDER=0>-, and 7s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-hydroxyderivatives of s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-sitosterol, campesterol, stigmasterol, and brassicasterol were identified by comparingthin-layer chromatography mobilities, specific color reactions, and mass spectral data with those ofthe corresponding hydroxy derivatives of cholesterol, which were synthesized in the same manner.The phytosterols had the same behavior to photooxidation as cholesterol and, moreover, the differentphytosterols photooxidized at about the same rate. The mass spectra of the trimethylsilyl ethers ofthe hydroxy derivatives of the phytosterols investigated and of the corresponding hydroxy derivativesof cholesterol have the same fragmentation patterns and similar relative ion abundances.Keywords: Sterols; phytosterols; hydroxysterols; photooxidation; gas chromatography/massspectrometry; GC/MS; mass spectra; trimethylsilyl ether