Studies on the effect of 5,5'-diphenylhydantoin on in vitro protein synthesis in rat brain

Previous investigators have reported binding of the drug 5,5'-diphenylhydantoin (DPH) to RNA and DNA and an effect of this compound on protein synthesis. We have studied the effect of DPH on in vitro protein synthesis by investigating the possible role of this drug on poly-Uracil-directed polyphenylalanine synthesis and natural mRNA-directed amino acid incorporation into polypeptides. There was no demonstrable effect of DPH on either of these reactions. It was also found the DPH did not alter the rate of aminoacylation of purified rat liver tRNAs. The in vivo daily administration of DPH to animals for a period of 2 weeks did not appear to affect the in vitro poly-Uracil-directed polyphenylalanine synthesis (chain elongation aspects of protein synthesis) in adult rat brain. It was also found that DPH did not inhibit DNA-dependent RNA synthesis as catalyzed by RNA polymerase. These studies do not support the hypothesis that DPH plays a role in protein synthesis in adult brain cells.