764 



Hall, Miller, and Herrero 



Table 3. Distribution of radioactivity in Coleus material. 



Petroleum Ether-soluble Fraction 



When lyophilized Coleus material was extracted with 80 per cent 

 boiling ethanol, the alcoholic extract reduced in volume and ex- 

 tracted with petroleum ether, 54.5 per cent of the total activity re- 

 mained in the petroleum ether-soluble fraction (Table 3). Radio- 

 assay of the chloroplast pigment fraction (Table 4) showed that caro- 

 tene retained most of the activity. Single dimensional radiochromato- 

 grams in six solvent systems showed only one radioactive spot through- 

 out the series, tentatively identified as carotenoids (Figure 6). Radio- 

 chromatography of the pigments in 1 per cent petroleum ether in n- 

 propanol exhibited one radioactive spot superimposed on the carotene 

 spot in the paper with an Rf value of 0.87. 



A number of detailed experiments have been conducted with 

 cotton and the results confirm those obtained with Coleus. Ether ex- 

 traction of lyophilized cotton leaves, reduction in volume and ex- 

 traction with petroleum ether (Figure 7), and radiochromatographing 

 in five solvent systems have demonstrated that most of the radioactiv- 

 ity is associated with the carotene fraction. Strip counting of the 

 chromatogram illustrated in Figure 8 showed that the radioactivity 

 coincides with the carotene spot on the chromatogram. 



Tabic 4. Distril)ution of radioactivity in Coleus pigments. 



Fraction 



Pet. ether extract . 

 Chlorophyll a . . . , 

 Chloropiiyll b. . . 



Carotene 



Xantho|)iiylls . . . 

 Not Mccoiintcd f()i- 



Volume, 



Ml. 



60 

 30 

 30 

 50 

 50 



Counts/ 

 Min/Ml 



4.045 

 446 

 205 



3.138 

 767 



Total 

 Activity 



242,700 



13,400 



6 . 1 50 



156,900 

 38,350 

 27 , 920 



Per Cent 



100.0 



5.5 



2.5 



64.6 



15.8 



11.5 



