MUTAGENS OF POTENTIAL SIGNIFICANCE 201 



H3C-N^ ' 



C AFFE I N E HYPOX ANTH I N E 



Figure 27. Structure of caffeine and hypoxanthine. 



Caffeine = 1,3,7-trimethylxanthine; theobromine = 

 3,7-dimethylxanthine; theophylline = 1,3-dimethj'lxan- 

 thine. Hypoxanthine = 6-oxypurine; adenine = 6-amino- 

 purine; guanine = 2-amino-6-oxypurine. Uric acid = 

 2,6,8-trioxypurine. 



acid precursor, hypoxanthine. Theophylline is present in very small 

 amounts in tea but is used medicinally for its diuretic and cardio- 

 vascular effects. Theobromine is a major alkaloid of cacao; a cup of 

 chocolate contains about 250 mg. Coffee beans contain about 1 per cent 

 caffeine, and also chlorogenic acid (a steroid), furfuryl alcohol, valeric 

 acid, phenol, pyridine, and various volatile oils. An average cup of 

 coffee contains about 130 mg caffeine. Tea leaves contain 2 to 3 per 

 cent caffeine, cola seeds 1 to 3 per cent, and a glass of cola drink 

 usually contains about 30 mg. 



Atwood: Salicylates ought to be in your Category III. 



Goldstein: I don't know. It's a matter of judgment as to where you 

 put them. I think, if we asked in this room, ''What was your caffeine 

 exposiu'e within the last week?" everybody would raise his hand and 

 it would turn out to be considerable. But if we asked what the salicyl- 

 ate exposure was, I think that you would get a very small response. 

 There is an important difference in degree of exposure. 



Zamenhof: Dr. Goldstein mentioned ascorbic acid, and I want to say 

 a few words about the mutagenic action of this vitamin. It was first 

 reported by McCarthy (39) and then confirmed by us (61) that even 

 in very small doses, ascorbic acid inactivates transforming principle. 

 In our hands, a concentration of 10 ■* M was sufficient for this effect, 

 and, since agents which in very small doses inactivate transforming 

 principle are also potential mutagens, it is of interest to investigate 

 ascorbic acid from this point of view. Clark, in 1955, in the Proceedings 



