CAROTENOIDS 



way. x-Carotene, first observed in yellow maize ^** (see p. 43) is, 

 in all probability, ^-carotene as is the *' carotene I " reported from 

 the same source by Baumgarten, Bauernfeind and BorufF. ^'^^ This 

 being so, we can assume that ^[-carotene occurs in some Indian varieties 

 of orange (Citrus aurantium) (reported as x-carotene). ^ ^ ' 



(vii) Other carotenes (including colourless polyenes). Porter and 

 Lincoln ^ * * have examined in great detail the carotenoid composition 

 of many tomato crosses involving L. esculentum, L. hirsutum and L. 

 pimpinellifolium ; they have found what appear to be a series of 

 derivatives of lycopene produced either by the step-wise addition of 

 four hydrogen atoms to the parent carotenoid or (as they consider 

 more probable) the step-wise removal of four hydrogen atoms from a 

 saturated precursor (see p. 68 for a full discussion). The first in this 

 series is tetrahydrolycopene which is considered to be identical with 

 neurosporene first reported in Neurospora crassa and lately in other fungi 

 (see p. 103) ; then follows octahydrolycopene which is probably ^- 

 carotenBy already discussed. This completes the coloured members of 

 the series for the next compound is phytofluene which is colourless but 

 exhibits a characteristic bluish-green fluorescence in ultra-violet 

 light. Zechmeister i ^ s- 1 e o ^nd his colleagues first obtained phytofluene 

 from tomatoes and other plant sources not containing chlorophyll (e.g., 

 flower petals and fungi) and its quantitative occurrence in some fruit 

 is recorded in Table 3. A little later Porter and Zscheile ^ * ^ indepen- 

 dently also reported the presence of this colourless polyene in tomatoes. 

 Zechmeister and Sandoval, i « ». i « » although not able to isolate phyto- 

 fluene in crystalline form, showed that it is a C40 compound (C4oH84 4^2) 

 with the carotenoid skeleton. 



It contains seven unsaturated linkages, five of which are conjugated. 

 They did not feel justified in further defining its structure but Porter 

 and Lincoln^** consider it to be dodecahydrolycopene. 



Phytofluene does not occur in green plant leaves or in the leaves of 

 the tree Cinnamonum camphorum at any stage of development. 



Recently phytofluene has been reported in the wood of Acacia 

 acuminata. ^ ' ^a 



Zechmeister and Pinkard^'^ have lately found in ripe tomatoes a 

 compound very similar spectroscopically to phytofluene but differing 

 in chromatographic and partition behaviour ; it appears to be a 

 hydroxy phytofluene and has been named phytofluenol. 



The colourless unsaponifiable substance which precedes phytofluene 

 on an adsorption column ^ * • is now considered to be hexadecahydro- 

 lycopene ^ * • and has been named phytoene ; tomato selections have 



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