The effect of 4-aminopyrazolo(3,4- d)pyrimidine and guanine on ehrlich ascites cells in culture

Abstract

APP (5 × 10 −6 M) exerts slight inhibitory effects (10–20 per cent) for ca 20 hr on cell multiplication, DNA, RNA, and protein synthesis by Ehrlich ascites cells in culture. Combinations of APP and non-inhibitory concentrations of guanine (2.5 × 10 −5–4 × 10 −4 M) result in marked enhancement of these inhibitory effects; DNA synthesis being most affected. In this respect, guanine is the most effective agent; guanosine and deoxyguanosine were less effective, and xanthine and xanthosine were ineffective. These inhibitory effects are prevented completely by adenine (5 × 10 −5 M) or 5-amino-4-imidazole carbox-amide (5 × 10 −4 M). Since other natural purine or pyrimidine bases, nucleosides or deoxynucleosides were either less effective or ineffective in this respect, inhibition appears to result from an “adenine deficiency”.