Organotins‐promoted peroxidation of unsaturated fatty acids: A new antioxidative scavenger for promoters

The organotin compounds RnSnX4‐n are promoters of lipids peroxidation. The influence of (CH3)2SnCl2, (C2H5)2SnCl2, and SnCl2 upon the radical chain oxidation of oleic acid as model substrate R′H for lipid peroxidation in the simultaneous presence of porphyrins (free bases of meso‐tetrakis(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)porphyrin (R″4PH2) and of meso‐tetraphenylporphyrin (TPPH2)) has been studied. The monitoring of the unsaturated acid peroxidation level has been performed by the determination of the total concentration of isomeric hydroperoxides as well as of the thiobarbituric acid reactive substances, as markers of carbonyl compounds formation following the hydroperoxides decomposition. The organotin compounds demonstrate prooxidative activity. The promoting effect of these compounds decreases in the presence of TPPH2. The free‐base porphyrin R″4PH2, containing the antioxidative phenolic moieties (2,6‐di‐tert‐butylphenol), demonstrates the acute inhibitory effect upon the acid's peroxidation. The analogous results have been achieved when compared with the influence of CH3HgI and HgCl2 upon the acids peroxidation of oleic acid in the presence of porphyrins. This fact points out that meso‐tetrakis(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)porphyrin shows the activities of both the antioxidant and of the scavenger for metals and might be used as a new antioxidative scavenger preventing lipids peroxidation.