EFFECTS ON GLYCOLYSIS 487 



Menadione has similar effects on the pattern of gkicose metabolism in 

 guinea pig nonphagocytosing polymorphonuclear leucocytes (see accom- 

 panying tabulation), in that C^^Oa arising from glucose- l-C^'' is markedly 



Menadione 

 Control bisulfite 



(0.15 mM) 



1 ,4-Naphthoquinone 



(0.3 mM) 



9.4 



97 



C-l/C-6 ratio 12.9 180 



stimulated while that from glucose-6-C^* is unaffected, indicating an ac- 

 tivation of the pentose-P pathway (Iyer et al., 1961). However, here, in 

 contrast to brain, the pentose-P pathway normally is to some extent 

 active, and there is a mvich greater elevation of respiration. The effects of 

 menadione mimic those changes occurring when phagocytosis is initiated, 

 so that menadione has relatively little action on glucose metabolism in 

 phagocytosing leucocytes. 



The thorough study of the effects of 104 quinones on aerobic glycolysis 

 in Schistosoma mansoni by Bueding and Peters (1951) presents interesting 

 possibilities of correlating structure with inhibitory activity, but certain 

 factors make accurate comparison difficult. First, the degree of penetration 

 into the worms may limit the actions of some of the quinones. This may 

 be responsible for the low activities of the sulfonates of both the 1,2- 

 and 1,4-napthoquinones, but could also play a role in determining the po- 

 tencies of some of the nonionic quinones. Second, aerobic glycolysis is 

 measured and this is dependent on several pathways and many factors, so 

 that the actions of all these quinones cannot be attributed necessarily to 

 a common mechanism. Third, the metabolism of this organism is unusual; 

 e. g., glucose is transformed mainly to lactate aerobically, since the systems 

 for pyruvate oxidation are deficient, and changing to anaerobic conditions 

 does not alter the rate of glucose utilization or lactate formation. Quite 

 possibly the mechanisms of inhibition in these worms are different from 

 those in mammalian tissues. Bueding and Peters pointed out that there 

 is no correlation between the glycolytic inhibitions here and the inhibitions 

 of respiration or glycolysis in other organisms or tissues. There is certainly 

 no good evidence that the inhibition in Schistosoma is related basically to 

 reaction with SH groups. Although addition of a methyl group to menadione 

 in the 3-position markedly reduces the activity, some of the most potent 



