Preparation of fatty acid cholesterol ester hydroperoxides by photosensitized oxidation

Preparation of fatty acid cholesterol ester hydroperoxides was undertaken w ith the purpose of evaluating their biological effects on cell growth. Chol esterol stearate, oleate, linoleate and alpha-linolenate were oxidized usin g methylene blue as a photosensitizer. The structures of all compounds were established by mass spectrometry and by nuclear magnetic resonance. The ph otosensitized oxidation of cholesterol oleate gave two hydroperoxide isomer s: 9-hydroperoxy-trans-10-octadecenoate, and 10-hydroperoxy-trans-8-octadec enoate. In the case of the cholesterol linoleate, hydroperoxide isomers for med were: 9-hydroperoxy-trans-10, cis-12-octadecadienoate; 10-hydroperoxy-t rans-8, cis-12-octadecadienoate; 12-hydroperoxy-cis-9, trans-13-octadecadie noate; 13-hydroperoxy-cis-9, trans-11-octadecadienoate. The oxidation of th e cholesterol alpha-linolenate gave a mixture of six hydroperoxide isomers, at positions 9, 10, 12, 13, 15 and 16 of the fatty acid chain. The photose nsitized oxidation of cholesterol stearate produced a formation of hydroper oxide at position 5 alpha of cholesterol. The same hydroperoxide isomers on the fatty acid chain were obtained as described in the literature for the fatty acid methyl esters. (C) 1999 Published by Elsevier Science ireland Lt d. All rights reserved.