CAROTENOIDS IN LAND PLANTS 



Modern investigators have been stimulated by Zechmeister's work 

 to search for m-isomers in Hving tissues. Beadle and Zscheile ^ ® claim 

 to have isolated a w^o-^-carotene from spinach, asparagus, and broccoli 

 leaves, but Griffith and Jeffrey ^ ^ could find no trace of neo-[3-carotenes 

 in fresh extracts of tobacco leaves. A long and critical examination of 

 a large number of fresh grasses has, however, convinced Kemmerer, 

 Fudge and Fraps ^ 2 that the carotene fraction of a grass contains, on 

 the average, 77-7 per cent, of p-carotene, 12-9 per cent, of neo-^- 

 carotene u, and 9-4 per cent, of n^o-p-carotene B. Both these isomers 

 have also recently been observed in the leaves of cauliflower, carrot, 

 lettuce, spinach, fenugreek and rape ^ 3. Zechmeister, ^ « from spectro- 

 photometric considerations, is inclined to believe that weo- [3 -carotene 

 u is J-mono-m-p-carotene, and w£o-p- carotene b is .? : 6-di-cts-^' 

 carotene, where the italicized numerals indicate double bonds and not 

 carbon atoms. 



25-0 



20-0 





15-0 



10-0 



5-0 



320 



360 



400 440 



Wavelength (mfx) 



480 500 



Fig. 3. — Absorption spectrum in Iso-octane of Neo- p-carotene B, Neo-^-carotene 

 U. (From Bickoff, £. M., White, L M., Bevenue, A. and Williams, K. T. 

 {1948) J. Ass. Off. Agric. Chem., p. 633.) 



11 



