52. New antioxidants

PRESERVATIVES flavonoids while largely degraded in the body appear to the extent of 3-10~o in the urine. Demole, V. (1962). Toxicit6, r6sorption, 61imination de la flavone synth6tique. Helv. physiol, acta 20, 93. 52. NEW ANTIOXIDANTS Oats have been shown to contain an antioxidant which contains a 3,4-dihydroxycinnamoyl (caffeoyl) group esterified with an aliphatic alcohol (Daniels & Martin, Nature, Lond. 1961, 191, 1302). The following caffeoyl esters have now been prepared: l-caffeoyl glycerol (I), l-palmitoyl-2,3-dicaffeoyl glycerol (II) and 1,2,3-tricaffeoyl glycerol (III) and their antioxidant activities examined. I is soluble in water and alcohol but only sparingly soluble in ether; II and III are insoluble in water but dissolve in methanol and ether; all 3 compounds are soluble in acetone. The antioxidant activities of I, 1I and III in oat oil are similar to that of propyl gallate or butylated hydroxytoluene. [In view of the doubt that has been cast upon the safety of one of the most frequently used antioxidants, investigation of the value of these new compounds would seem to be a top priority task.] King, H. G. C. (1962). New antioxidant glycerides. Chem. & Ind. 1468. 53. ANTIOXIDANTS AS VITAMIN E SUBSTITUTES The ability of antioxidants to act as substitutes for vitamin E, has been studied extensively but the dietary experiments have not always taken into account whether the antioxidant is absorbed into the body or stored in the tissues, properties which greatly influence the outcome of such tests. In the present work, the presence of each antioxidant in the liver was checked by means of in vitro tests involving lipid peroxidation. At the same time the efficiency of the same antioxidant in vivo was measured by its ability to prevent exudative diathesis in chicks given a diet deficient in vitamin E and biologically active selenium. The results clearly indicate that the ability of antioxidant to substitute for vitamin E is primarily dependent on its availability to the body and subsequent deposition in the tissues. From this point of view ethoxyquin and N,N'diphenylphenylenediamine (DPPD) were most effective, while butylated hydroxytoluene (BHT) and di-tert-butyl-4-methylphenol were active. Nordihydroguaiaretic acid and 2,5-di-tert-amylhydroquinone were inactive. [Tissue storage of the type which makes an antioxidant a useful substitute for vitamin E renders it less suitable a s a direct food additive. Francois & Pihet (Ann. inst. natl. recherche agron. Sdr. D 1960, 9, 195) fed a number of antioxidants to pigs and chicks in a concentration of 0.1 ~ of the diet for 2-4 months. All they could find was DPPD in depot fat and kidneys of pigs; and DPPD and BHT in depot fat of chicks.] Krishnamurthy, S. & Bieri, J. G. (1962). Dietary

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antioxidants as related to vitamin E function. J. Nutr. 77, 245. 54. A F U R T H E R REPORT " It is known that diets with a high linoleic" acid content lead to softening of the brain in chicks, and an increased requirement for vitamin E or other antioxidants (Machlin & Gordon, Proc. Soc. exp. Biol., N . Y . 1960, 103, 659). Feeding vitamin E-deficient diets to cockerels for 2 yr causes testicular degeneration, but there is no evidence that such diets affect egg production or fertility in hens. In the present study, the effects of diets having high linoleic acid contents, on egg production and fertility in hens were investigated together with their requirements for vitamin E or other antioxidants. Hens were fed a basal ration in which 7 0 ~ of the fat was in the form of linoleic acid. After 8 weeks, egg production had fallen from 7 8 ~ - 2 5 ~ ; only 3 7 ~ of the eggs were fertile and none of these hatched. Addition of 20 or 100 I.U. vitamin E/lb of the basal diet however eliminated these toxic effects. The antioxidant ethoxyquin (I) at a level of 0.075 of the diet prevented the drop in egg production and fertility, but only 4 ~ of the eggs hatched; 0.3 ~ of dietary I restored hatchability to normal. Reducing the linoleic acid content of the diet a,lso restored normal laying and hatchability characteristics. The authors concluded that food containing a high proportion of linoleic acid produce a dietary stress to which chicks respond by developing brain softening, and hens respond by a lowering of egg production and a reduction in the fertility and hatchability of the eggs produced. This stress may be abolished in hens, by feeding increased amounts of vitamin E or I or by decreasing the proportion o f linoleic acid in the diet. Machlin, L. J., Gordon, R. S., Marr, J. E. & Pope, C. W. (1962). Effect of antioxidants and unsaturated fatty acids on reproduction in the hen. J. Nutr. 76, 284. Preservatives 55. SULPHITE AND S U L P H U R DIOXIDE TOXICOLOGY A good review which also covers the toxicity of sulphites. In particular it mentions the work of Fitzhugh et al. (J. Pharmacol. 1957, 86, 37) who found that chronic feeding of sodium bisulphite caused harmful results, thought to be due to destruction of thiamine by the sulphur dioxide. Against this is quoted the study of Lockett & Natoff (J. Pharm. Pharmacol. 1961, 12, 48), who fed sodium bisulphite at 700 ppm in drinking water, when no toxic symptoms were seen. The harmful effects observed in the previous study might well have been caused by reaction products of SOs with components of the diet. Schroeter, L. C. (1961). Sulfurous acid salts as pharmaceutical antioxidants. J. pharm. Sci. 50, 891,