New Auxins From 'Maryland Mammoth' Tobacco 



(■)! 



After repeated fractional crystallization from anhydrous ether, con- 

 centrate A provided a small amount of waxy white solid which melted 

 at 70 to 72° C. and contained only carbon, hydrogen, and oxygen. 

 Its infrared and ultraviolet spectra were those characteristic of a long- 

 chain unbranched fatty alcohol such as 1-docosanol (melting point 

 73° C). Color tests for the indole nucleus were negative. Figure 3 

 shows the results of bioassays of the tobacco isolate and several of 

 the common naturally occurring alcohols. All together, more than 

 60 long-chain compounds were examined, and Figure 4 shows the 

 activity of one of these, 2-heptadecanol, at several concentrations. 

 With two exceptions, activity was found to be restricted to alcohols 

 containing from 17 to 22 carbon atoms and their acidic inorganic 

 esters (5). 



Repeated precipitation of concentrate B from methanol solution 

 with absolute ether resulted in a white crystalline material which pos- 

 sessed pronounced auxin activity, but which rapidly became dark and 

 gummy, even in the cold, with complete loss of activity. The crystal- 

 line material did not melt below 300° C, and also contained no nitro- 

 gen, phosphorus, sulfur, or halogen. Chemical studies and data from 

 infrared, ultraviolet, and emission spectra revealed that the active 

 material was the sodium salt of a long-chain unsaturated fatty acid. 

 A variety of other fatty acid salts has now been bioassayed, and some 



80 



160 240 



GROWTH, PER CENT OF CONTROL 



320 



Fig. 3. Growth-promoting activity of several naturally occurring long-chain alcohols. 



