536 VI. CAROTENOIDS AND RELATED COMPOUNDS 



berries of the mountain ash^^ and chestnut/* from the mango, ^^ and from 

 spinach and nettles. ^^-^^ A Hst of other sources of a-carotene in which the 

 pigment has been definitely identified is given in Table 3. 



c. Related Compounds. Only a relatively few of the comparable 

 derivatives described for /3-carotene have been reported in the case of a- 

 carotene. 



(a) a-Carotene Mono-epoxide, C40H56O. a-Carotene mono-epoxide origi- 

 nates on oxidation of a-carotene with perphthalic acid.^®'^ It separates in 

 golden-yellow crystals (m.p., 175°C.) from a benzene-methanol mixture. 

 On treatment of an ether solution of the epoxide with aqueous concentrated 

 hydrochloric acid, the acid layer assumes a weak ephemeral blue color. 

 Only the mono-epoxide is formed in the case of a-carotene^®-; this oxygen 

 bridge occurs on the ^S-ionone portion of the molecule. The fact that the 

 formation of the furanoid structure is related to epoxide synthesis and can 

 occur only with the /3-ionone residue explains the failure to form an a-caro- 

 tene di-epoxide. According to Karrer et al.,^^^ a-carotene mono-epoxide is 

 found naturally in such different flowers as Tragopogon pratensis (goat's 



" Data adapted from P. Karrer and E. Jucker, Carotinoide, Birkhauser, Basle, 1948. 

 Translated and revised by E. A. Braude, Elsevier, New York, 1950. 



'' K. Schon, Biochem. J., 29, 1779-1785 (1935). 



<= H. Willstaedt, Chem. Zentr., 1938, II, 2272; Srensk Kern. Tid., 49, 318-323 (1937); 

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'^ L. Zechmeister and L. v. Cholnoky, Ann., 509, 269-287 (1934). 



' L. Zechmei.ster and A. Polgdr, J. Biol Chem., 139, 193-198 (1941). 



/ E. Lederer, Compt. rend. soc. biol., 117, 1083-1085 (1934); Bull. soc. chitn. bioL, 20, 

 611-634 (1938). 



" A. Winterstein and U. Ehrenberg, Z. physiol. Chem., 207, 25-34 (1932). 



* R. Kuhn and A. Winterstein, Ber., 67, 344-357 (1934). 



' L. Zechmeister and P. Tuzson, Ber., 67, 824-829 (1934). 

 '■ J. Tischer, Z. physiol. Chem., 259, 163-170 (1939). 



* K. Schon and G. Mesquita, Biochem. J., 30, 1966-1969 (1936). 

 ' A. Winterstein, Z. physiol. Chem., 215, 51-58 (1933). 



"• J. Tischer, Z. physiol. Chem., 252, 225-233 (1938). 



" J. C. Lanzing and A. G. van Veen, Geneeskund. Tijdschr. Nederland. Indie, 77, 2074- 

 2094 (1937); Chem. Abst., 31, 8625 (1937). 



* I. M. Heilbron, E. G. Parrv and R. F. Phipers, Biochem. ./., 29, 1376-1381 (1935). 

 " P. Karrer and E. Jucker, Helv. Chim. Acta, 27, 1585-1588 (1944). 



" H. A. Schuette and R. C. Palmer, Oil & Soap, I4, 295-297 (1937); Chem. AbsL, 32, 

 377 (1938). 



■■ W. C. Sherman, Food Research, 5, 13-22 (1940). 



' R. Kuhn and E. Lederer, Ber., 64, 1349-1357 (1931). 



' R. Yamamoto and T. Muraoka, Sci. Papers Inst. Phys. Chem. Research Tokyo, 19, 

 127—133 (1932) 



" K. Schon, Biochem. J., 30, 1960-1965 (1936). 



" G. S. Fraps and A. R. Kemmerer, Ind. Enq. Chem., Anal. Ed., 13, 806-809 (1941). 



"■> L. Zechmeister and P. Tuzson, Ber., 67, 154-155 (1934). 



^ N. A. S0rensen, Chem. Zentr., 1934, I, 3817. Cited by P. Karrer and E. Jucker, 

 Carotinoide, Birkhauser, Basle, 1948. Translated and revised by E. A. Braude, Elsevier, 

 New York, 1950. 



y E. Lederer, Compt. rend. soc. biol., 117, 1086-1088 (1934). 

 ' E. Lederer, Compt. rend., 201, 300-302 (1935). 



"" P. J. Drumm and W. F. O'Connor, Nature, I45, 425 (1940). 



"'' D. L. Fox, Proc. Natl. Acad. Sci., 23, 295-301 (1937). 



" N. A. S0rensen, Kgl. Norske Videnskab. Selskabs Forh., 6, No. 40, 154-157 (1933); 

 Chem. Abst., 28, 4758 (1934). 



