Iron compounds Tocopherols

Vitamin E compounds can be detected (about 20 /tg) as dark spots in UV light. They appear violet and detection is appreciably more sensitive (0.02 /tg) on layers that contain 0.02% Na-fluorescein. Moreover, these are visible in daylight as reddish spots (limit of detection 2 fig). The same effect is produced by spraying with fluorescein or dichlorofluorescein reagent. Nonspecific visualization procedures for tocopherols and tocotrienols are based on spraying with sulfuric acid, molybdophosphoric add, antimony(V) chloride, dipyridyl-iron reagent, nitric add, and copper(II) sulfate-phosphoric add [1-4]. 

Various carbonyl compounds and decomposition products of methyl linolenate hydroperoxides were tested for their interaction with DNA by measuring fluorescence in the presence of ferric chloride and ascorbic acid. 2,4-Alkadienals and 2,4,7-decatrienals were among the most active decomposition products of linolenate hydroperoxides (Table 5.8). To determine the type of reactive species involved in fluorescence formation with DNA, the effect of free radical antioxidants and a singlet oxygen quencher were examined. )3-Carotene, a-tocopherol and phenolic antioxidants strongly inhibited DNA fluorescence formed by decomposition of linolenate hydroperoxides in the presence of ferric chloride and ascorbic acid (Table 5.9). These results indicate that singlet oxygen and free radical species are important intermediates in the interaction of linolenate hydroperoxides with DNA in the presence of iron and ascorbic acid. 

The source of initiation has also been shown by Palozza et al. (77) to modify tocopherol s effectiveness as an antioxidant. Three types of initiation were studied on rat liver microsomes by these investigators and they included enzymic peroxidation induced by NADPH, ADP and iron the water-soluble azo compound... 

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