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COMMUNICATIONS TO THE EDITOR
Vol. 63
our first paper‘ on this subject, we did not describe the formation of alcohols from esters over Raney nickeLg While we plan to continue our work with coumarin and other lactones, the investigations already mentioned4x6conclude our interest in the behavior of simple esters over Raney nickel and we now have no plans for extending this phase of the work.
able in seeds of castor bean, almond, maize, cucumber, flax or sunflower, nor in etiolated barley seedlings in which rapid oxidations of the carotenoids are also known to O C C U ~ . ~ Many factors influence the oxidation of organic substances induced by concomitant enzymatic oxidation of fats. Easily autooxidizable carotenoids (as eschscholtzxanthin) 10 were decolorized (9) The communication of Ovakimian, Kuna and Levenea indimore rapidly than stabler pigments (as zeaxancates a misunderstanding of this point. thin) .g In highly unsaturated fatty compounds DEPARTMENT OF CHEMISTRY AND CHEMICAL ENGINEERING PETERI.. DE BENNEVILLE(ethyl linolenate), the oxidatiou of carotenoids OF PENNSYLVANIA WM. R. MCCLELLAN was much slower than that of the same pigments UNIVERSITY PHILADELPHIA, PENNSYLVANIA RALPHCONNOR dissolved in olive oil, an indication of competition RECEIVED NOVEMBER 3, 1941 between the fat and the carotenoid for the oxidizing agent. UNSATURATED FAT OXIDASE: SPECIFICITY, Chlorophylls a and b were oxidized to colorless OCCURRENCE AND INDUCED OXIDATIONS substances by the system of fat, enzyme and Sir : oxygen. p-Phenylenediamine (but not the 0 or p An oxidase found in soybeans converts unsatu- isomer) was oxidized to a blue pigment, a reaction rated fats into Carotenoid pigments similar to that produced by the cytochrome conior vitamin A present in the fat are oxidized by plex. Dihydroxyphenylalanine (dopa) was oxiunstable intermediate products, not by direct dized to the black pigment melanin, a reaction enzymatic action nor by the relatively stable fat also catalyzed by the highly specific dopa oxidase. peroxides.3-8 Ascorbic acid was oxidized a t a slow rate. In the This enzyme (soy beans ground with 5 parts of absence of fats or if heated enzyme preparations water and centrifuged) has now been found to were used, none of these induced oxidations took oxidize directly only those compounds containing place. H H Polyphenols exhibited remarkable effects upon the -c=c(cH~)~c(o)group with cis configurathe enzymatic oxidation of fats and upon the intion. For example, oleic, ricinoleic, linoleic and duced oxidation of other substances. Hydrolinolenic acids and their esters absorbed oxygen quinone, pyrogallol and catechol (10 mg. per 2-3 rapidly. Under the same conditions, oleyl alcoml. of enzyme solution) prevented the absorption hol, elaidic and erucic acids (in decalin) and a of oxygen by unsaturated fats and thus prevented variety of other unsaturated compounds were not the induced oxidation of other substances. Phlooxidized (many of these compounds were genroglucinol and resorcinol, by contrast, did not erously donated by Dr. George Burr and by Dr. inhibit absorption of oxygen by the fat or decoloriC. R. Noller). zation of carotenoids. They did, however, preThe unsaturated fat oxidase has been detected vent oxidation of p-phenylenediamine to the blue in seeds of various legumes: Acacia rnelunoxyln, alfalfa, scarlet runner bean, white clover, Labur- pigment. Formation of this blue pigment renum anagyroides, Lupinus albus,2 L. Benthumii, sulted from reaction between the amine and the L. Greyi, L. nanus, garden peas (green and dry), fat peroxides. This reaction was inhibited by all purple vetch (green and dry). It was not detect- the polyphenols, most of which were oxidized at a slow rate. (1) AndrC and Hou, Compl. rend., 194, 645 (1932); 195, 172 (1932). (2) Craig, J . B i d . Chcm., 114,727 (1936). (3) Haas and B o b , Chcm. Abs., 28,4137 (1936). (4) Tauber, Teis JOURNAL, 62, 2251 (1940). (5) Sumner and Dounce, Eneymologia, I , 130 (1939). (6) Sumner and Sumner, J . Biol. Chcm., 194,531 (1940). (7) Siillmann, Hela. Chim. Acta, 24, 465, 646 (1941). (8) Fry, Schultz and Light, Ind. Eng. Chem., 28, 1254 (1936).
CARNEGIE INSTITUTION OF WASHINGTON HAROLD H. STRAIN DIVISIONOF PLANTBIOLOGY STANFORD UNIVERSITY, CALIFORNIA RECEIVED NOVEMBER 5, 1941 (9) Strain, “Leaf Xanthophylls,” Carnegie Institution of Washington Publ. No. 490 (1938). (10) Strain, J . Biol. Chem., 129, 425 (1938).
