" Calculated from the data of Schopfer and Keller (1951). 



the effects of light on the inhibition may indicate some relationship. The 

 white form may be deficient in nicotinate or the pyridine nucleotides when 

 grown in the light, and thus it may be more susceptible to those quinones 

 interfering with NAD(P) synthesis (if similar relations hold as in some of 

 the fungi) and nicotinate will then be able to reverse the inhibition. Un- 

 fortunately the effects of nicotinate on the other inhibitions were not de- 

 termined. 



The screening of compounds to find useful antimalarials led to the dis- 

 covery of the activity of hydrolapachol but since much more active com- 

 pounds with longer side chains were soon found (e. g. SN-5949), the actions 

 of these naphthoquinones on Plasmodium will be discussed elsewhere 

 (Fieser, 1948). The simpler benzo- and naphthoquinones are relatively 

 inactive (Wiselogle, 1946 b). The motility of Trypanosoma equiperdiim is 

 first inhibited by 0.18 mM l,2-naphthoquinone-4-sulfonate, at which con- 

 centration glycolysis is depressed 40% and respiration 74% (Meyerhof 

 and Randall, 1948). Lower concentrations can significantly inhibit respi- 

 ration and glycolysis without affecting the motility. It is able to exert a 



