2 PROLYCOPENE 125 



2. PROLYCOPENE C4oH5e 



In 1941, Zechmeister and collaborators^^ discovered a new polyene 

 pigment in the "tangerine tomato", a variety of lycopersicum escuUntum. They 

 proposed the name prolycopene for this new pigment which has also been 

 found in several other plants including Butia capitata^'^, Butia eriospatha 

 Becc.^^, Pyrocantha angustifoUa^^ , Evonymus fortunei^^ and Mimulus longiflorus 

 Grant^^. 



According to Zechmeister and collaborators^^'^^ prolycopene is to be 

 regarded as a naturally occurring stereoisomer of lycopene. The chromophoric 

 system of this pigment is assumed to contain 5 to 7 czs-double bonds in contrast 

 to lycopene which is believed to have an exclusively ^raws-arrangement of 

 double bonds. Under the catalytic influence of iodine, prolycopene is converted 

 into a complicated mixture of stereoisomers which includes the natural [trans)- 

 lycopene. 



Prolycopene crystallises from petroleum ether or ethanol in plates, m.p. 

 111°. In other solvents, this pigment is more easily soluble than lycopene. On 

 chromatography on calcium hydroxide it gives rise to a zone below that of 

 lycopene. 



Solvent: Absoyption maxima: 



Carbon disulphide 500.5 469.5 m^ 



Benzene 485 455.5 m[x 



Chloroform 484 453.5 m/t 



Ethanol (471) (445) m^ 



Petroleum ether 470 443.5 m^ 



Zechmeister and Pinckard^' discovered 6 new lycopene isomers, believed to 

 contain 4 to 7 cis-double bonds, in ripe berries oipyracantha angnstifolia (Schneid). 

 They were designated according to decreasing strength of adsorption as poly-cfs- 

 lycopenes I-VI. Three of these compounds could be crystallised. 



M.p. Absorption nia.xim,a 

 in hexane solution 

 Poly-cis-h'-copene I . . . . 93-95° 444-445 m/i 



Poly-cis-lycopene II . . . 85-87° 441-442 m/z 



Poly-cis-lycopene III . . . 105-106° 443-446 m^ 



Poly-cis-lycopene IV 426 m/^ 



Poly-cis-lycopene V 431-432 m/z 



Poly-cis-lycopene VI 433 m^ 



References p. 16^-iyo. 



