HYDliOCAllBON CAllOTKNOIDS OF THE Vn, .SERIES 517 



enone,^^""^" which is converted lo azulrin by means of a mild oxidation 

 reaction/' yielded further support for tlie Karrer stnictur(\ Kuiin," in 

 1935, stated that the formuhi for /S-carotene definitely agrees with that 

 suggested earlier by Karrer. ®^''*''^** 



HjC C Hj H 3C C H J 



^C CHj CMj CHj CHj c^ 



/'\ hhIhhhIhhhhIhhhIhh /''\ 

 HzCz 6C • c : c • c ; c • c : c • c : c • c : c • c : c • c : c • c : c • c : c • Cs' 2 c H 2 



I II 7 B 9 10 II 18 13 14 15 IS' 14' 13' 12' M' 10' 9' 8' 7' || 



HzCs sC Cs' JCHj 



\,/ \ / \4'/ 



C CHj HjC C 



H2 H2 



j3-Car<)tenc (Karror nuinljeriiig) 



HjC CHj H iC CHj 



f* CHj CHj CHj CHj r- 



/2\ hhIhhhIhhhhIhhhIhh /«'\ 

 HjCs iC' C :c- c: C -c: C- c: C- C:C' C: C- C: C- C: C- C: C- Ci' sCHj 



I II I 2 3 4 5 e 7 8 9 10 II 12 13 14 IS 16 17 IS 11 I 



H2C4 SC Cj' 4'CHz 



Ns/ \ y \j'/ 



CHj HjC C 



H? Hz 



^-Carotene (Kuhn numbering) 



HjC CHj HjC CHj 



^f/ CHj CHj CHj CH, c 



/^\ hhIhhhIhhhhIhhhIhhh24\ 

 H2C3 iC'C:C'C:c*c:C'C:C'C:C'C:C'C:C'C:C'C:C'Ci9 23CH 



I II I 2 3 4 S 6 7 e 9 10 II 12 13 14 IS 16 17 IS II I 



H2C4 eC 020 22GH2 



\5/ \ / \2l/ 



C CHj HjC C 



H2 H2 



7-Carotene (Heilbron numbering) 



There are several methods for designating the carbon atoms in the 

 carotenoid molecule. The most common one is that employed by Karrer, 

 which is used throughout the present monograph. Alternative systems 

 are those of Kuhn and of Heilbron, also illustrated here.*^ 



b. Occurrence. /3-Carotene is the most widely distributed of any of 

 the carotenoids. At the same time, it is the one which has the greatest 

 pro\'itamin A activity of any of the members of this group which have been 

 investigated. It occurs in plants chiefly in connection with chlorophyll, 

 which maj' effectively mask the yellow color. However, in many fruits, it 



8' R. Kuhn and H. Brockmann, Ber., 65, 894-898 (1932). 



8^ R. Kuhn and H. Brockmann, Bn\, 66, 1319-1326 (1935). 



s* R. Kuhn and II. Brockmann, Z. phiisiol. ('hem., 213, 1-7 (1932). 



8« R. Kulni and H. Brockmann, Ber., 67, 1408-1409 (1934). 



87 R. Kuhn, Ann. Rev. Biochem., .'^, 479-496 (1935). 



88 P. Karrer and A. Helfenstein, Ann. Rev. Biochem., 1, 551-580 (1932). 



8' F. Mayer and k. H. Cook, The Vhcmislrij of Xataral Coloring Matter, Rcinhold, 

 New York, 1943. 



