CAROTENOIDS 



Goodwin and Gregory^ never detected carotene in either the sys- 

 temic blood or the portal blood of goats, after feeding them massive 

 doses of carotene in various forms. They also failed to find it in the 

 thoracic lymph of goats ; however, the lymph of goats recently 

 removed from green pasture does contain a fat soluble yellow pigment 

 which is not carotenoid ; it may be a chlorophyll degradation pro- 

 duct. Goodwin and Gregory also failed to detect carotenoids in the 

 butter, liver, ovaries and adrenals of goats. Goats' colostrum may 

 contain small amounts of carotene, ^ ^ ^ and traces have been recently 

 found in the liver of some but not all goats. ^ ^ ' 



High doses of carotene have also failed to produce accumulation in 

 either blood or body fat of rats, 2 2 2. 2 2 3 pjgg^ 1 2 e. 2 1 7. 2 2 9 qj. rabbits. ' 

 p- Carotene, however, may be present in pigs' retinas, ^ ^ * but is absent 

 from other organs. ^^o Beadle, Wilder and KraybilP^^ found that 

 the yellow fat occasionally encountered in pigs does not contain 

 carotenoids ; the colour was due to large amounts of linoleic acid 

 in the fat which arose from the feeding of excessive amounts of 

 flax seeds. 



Pease^^- and Willimott '^ ^ ^ encountered rabbits with a recessive 

 factor w^hich allowed xanthophylls but not carotenes to accumulate 

 in the subcutaneous fat. Willimott explained the phenomenon by 

 postulating the absence of a liver enzyme capable of oxidising xantho- 

 phylls. In the light of present day knowledge this cannot be accepted, 

 for in normal rabbits Goodwin and Gregory^ have never found 

 xanthophylls in the portal or systemic blood in transport to the liver, 

 nor in the liver itself. 



As was previously stated, carotene does not appear in the plasma of 

 these animals owing to the efliciency of the mechanism converting it 

 into vitamin A. Very little is known of the fate of ingested xantho- 

 phylls, but in rats Goodwin 2 3 '^ has obtained evidence that some at 

 least are absorbed, for after feeding free lutein (xanthophyll) he 

 recovered small amounts of mono- and diesterified lutein (xanthophyll) 

 from the intestinal wall ; no lutein (xanthophyll) was detected in any 

 other organ, and the fate of this absorbed pigment could not be traced. 

 It is interesting to note that Prelog and his collaborators consider that 

 the ionone derivatives which they have isolated from pregnant mares' 

 urine, may have been produced from the degradation of alimentary 

 xanthophylls. ^ 3 ^ 



The milk of the following species contain no more than minute 

 traces of carotenoids : goats, ^ » « rats, ^ » » Indian 2 3 « and Egyptian ^ ^ ^ 

 buffalo, and, by implication, elephants. ^ ^ » Ewes' and sows' colostrum 

 contain no carotenes. 2 7, 2 3 1 



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