340 CAROTENOIDS OF UNCERTAIN STRUCTURE XIV 



be an acid or an enol, as its colour is reversibly changed on addition of alkalis. 

 This behaviour and the single-banded absorption spectrum (maximum at 

 500 vcifx in carbon disulphide) are reminiscent of astacene, but mytiloxanthin 

 has a much lower melting point (140-144°). (The melting point of astacene is 



228°). 



37. CAROTENOID FROM THE BLOSSOMS OF SATIN OAK 



[Grevillea robusta) 

 Zechmeister and Polgar^^^ found, besides j3-carotene, cryptoxanthin and 

 xanthophyll, a previously unknown hypophasic carotenoid in the blossoms of 

 satin oak {Grevillea robusta). The pigment is only present in very small amounts, 

 so that neither its physical properties nor its constitution could be determined. 

 It crystallises in long plates. 



Solvent: Absorption maxima: 



Carbon disulphide 490.5 457 m/i 



Benzene 479.5 440.5 ran 



Petrol 457.5 430 raft 



38. CAROTENOIDS FROM DIATOMS, BROWN ALGAE AND 



DINOFLAGELLATES 



According to Strain, Manning and Hardin^"^, certain species of diatoms 

 and brown algae contain, besides fucoxanthin, a number of other carotenoids 

 which were named diatoxanthin, diadinoxanthin, neofucoxanthin A and neo- 

 fucoxanthin B. The chemical nature of these carotenoids is still entirely 

 unknown. 



According to the same authors, dinofiagellates Peridinium cinctum contain 

 pigments which were named dinoxanthin, neodinoxanthin, diadinoxanthin, 

 neodiadinoxanthin and peridinin. The chemical nature of these compounds is 

 also unknown. 



39. carotenoid from neurospora 



A new carotenoid named neurosporen has been isolated by Haxo^*^* from 

 the fungus Neurospora crassa. Neurosporen occurs together with lycopene, 

 y-carotene and rhodoviolascin (spirilloxanthin) and smaller quantities of 

 j8-carotene, and of four other pigments resembling 8-carotene, rhodopurpurin, 

 lycoxanthin and rhodopin. 



Neurosporen was obtained crystalline, m.p. 124°. It is a hydrocarbon and 

 has the molecular formula C^oHgg (± 2H). 



Solvent: Absorption maxima: 



Carbon disulphide 502.5 470.5 439.5 mn 



Petroleum ether 470 441.5 myt* 



References p. 341-343. 



