Indole-3-acetaldehyde in Playit Extracts 45 



Finally, a new, sensitive spray reagent for indole derivatives was 

 described by Harley-Mason and Archer in 1958 (15). This reagent is 

 p-dimethylaminocinnamaldehyde (DMCA) , a vinyl compound corre- 

 sponding to Ehrlich's reagent, p-dimethylaminobenzaldehyde 

 (DMBA) . DMCA, possessing an additional double bond, was expected 

 to give more intensely colored condensation products with the indole 

 compounds and is reported to be about ten times as sensitive as Ehr- 

 lich's reagent as a detector of indole and tryptophan. 



Basing our procedures on the work of Gray, Nitsch, and Harley- 

 Mason and Archer, we hoped to be able to clarify the situation with 

 respect to the occurrence of lAAld and IAN in ether extracts of etio- 

 lated pea epicotyls and heads of cabbage. 



MATERIAL AND METHODS 



The compound, lAAld-NaHSOs, was prepared from tryptophan 

 and NaOCl, following exactly the directions given by Gray (14) , ex- 

 cept that all quantities of material were reduced to one-half (starting 

 with 1.5 g. of tryptophan instead of 3 g., etc.) . Free lAAld, lAA, and 

 IAN were chromatographed (descending) on filter paper in the same 

 system as was used by Gray, namely 7i-butanol saturated with 2.8 per 

 cent aqueous ammonia. After 7 hrs. the paper was dried and sprayed 

 with a 1 per cent solution of dimethylaminobenzaldehyde in 1 N HCl. 

 lAAld and lAA gave practically the same Rf values as reported by 

 Gray who used the ascending technique, namely 0.92 to 0.95 and 

 0.23 to 0.25, respectively (Gray: 0.93 and 0.28 to 0.29). IAN, not tested 

 by Gray, ran at Rf 0.89. The color reaction of lAAld with DMBA is 

 bluish purple, changing to brownish. Weller, Wittwer, and Sell (29), 

 who obtained a sample of lAAld-NaHSOg from Gray, report that 

 lAAld runs at Rf 0.88 in 1-butanol saturated with 5 per cent NH4OH 

 and in 1-propanol: concentrated NH40H:HoO (60:30:10). 



The free aldehyde was obtained by adding 4 ml. water and 1 ml. 

 0.5 M NaoCOg to 5 ml. of an aqueous solution containing 0.5 or 1.0 

 mg. of lAAld-NaHSOg. The alkaline solution was shaken three times 

 with 8 ml. of peroxide-free ether; the ether, containing the aldehyde, 

 was adjusted to a volume of 25 ml. It is not yet known whether all of 

 the original lAAld is secured in the ether fraction by this procedure, 

 so quantities of lAAld are given as relative values only in the follow- 

 ing: 



IAN. This compound was purchased from the Aldrich Chemical 

 Company, 3747 N. Booth St., Milwaukee 12, Wisconsin. It was used 

 without further purification. 



p-Dimethylaminocinnamaldehyde (DMCA) (Aldrich, see above). 

 The reagent was prepared as directed by Harley-Mason and Archer 



