586 VI. CAROTENOIDS AND RELATED COMPOUNDS 



some years earlier. It has been reported only in the pumpkin. Little is 

 knoAvn about the structure of petaloxanthin. The empirical formula is 

 C^nHBeOs or C4oH5g03. A number of its properties indicate that it is closely 

 related to if not identical with antheraxanthin. 



(21) Miscellaneous Plant Pigments 



During the last decade, the number of different known plant carotenoids 

 has been largely increased. This is due largely to improved methods of 

 isolation, purification, and identification, which are mainly the result of 

 the application of chromatographic adsorption methods, ^^'^^^ new absorp- 

 tion procedures, ^^^~'^^ and new microchemical methods. ^^^'^^^ 



a. Eschscholtziaxanthin, C40H54O2 ± H2. This has been separated 

 from the petals of the California poppy {Eschscholtzia calif ornica) .^^'' It 

 has 12 double bonds and contains 2 hydro xyl groups. It is very labile in 

 the presence of oxygen. The pigment occurs in the poppy as an ester. 

 Eschscholtziaxanthin melts at 185-186°C., [a]el% = 225 ± 12° (in chloro- 

 fomi). The following esters have been prepared: eschscholtziaxanthin 

 diacetate, m.p., 200-240°C., [a]em = +132° (in chloroform) ; dipalmitate, 

 m.p., 100-110°C.; dibenzoate, m.p., 133°C., [a]el's = -142°; di-p- 

 nitrobenzoate, m.p., 260°C., [a]6m = -234°. 



b. Spirilloxanthin, C48H66O3. The pigment has been prepared from 

 the purple bacteria from well-water (Spirillum rubrum Esmarch) by van 

 Niel and Smith. '^^ It appears to be related to rhodoviolascin. 



c. Euglenarhodon, C40H48O4. Euglenarhodon is a tetraketone which 

 was discovered and named by Hardtl.^^* It has been prepared from the 

 red alga "water-bloom" (Euglena helioruhescens) .'^ Tischer^"^ reported 

 the presence of euglenarhodon in the form of the dipalmitate ester in the 

 resting spores of Haematococcus pluvialis. This would leave open to ques- 

 tion whether the pigment concerned is a reduction product of euglenarhodon 

 or whether two of the oxygens in the parent compound are actually present 

 as hydroxyls rather than as ketones. 



3" J. H. C. Smith and H. W. Milner, /. Biol. Chem., IO4, 437-447 (1934). 



3^2 E. S. Miller, G. MacKinney, and F. P. Zscheile, Plant Physiol., 10, 375-381 (1935). 



393 J. H. C. Smith, J. Am. Chem. Soc, 58, 247-255 (1936). 



394 K. W. Ilausser, R. Kuhn, A. Smakula, and K. II. Kreiichen, Z. phijsik. Chem., B29, 

 303-370 (1935). 



395 K. H. Slotta and E. Blanke, J. prakt. Chem., US, 3-17 (1935). 



396 H. Jackson and R. N. Jones, /. Chem. Soc, 1936, 895-899. 



397 H. H. Strain, /. Biol. Chem., 123, 425-437 (1938). 



398 C. B. van Niel and J. H. C. Smith, Arch. Mikrobiol, 6, 219-229 (1935). 



399 H. Hardtl, Botan. Cmtr. Ah(. A., Beihefte, 53, G06-G19 (1935). 

 «" J. Tischer, Z. phi/siol. Chem., 239, 257-269 (1936). 



«i J. Tischer, Z. physiol. Chem., 252, 225-233 (1938). 



