RT Journal Article SR Electronic T1 Influence of Thiols on Inhibition of Ribonucleic Acid Synthesis in Vitro by a 1-Nitro-9-aminoalkylacridine Derivative, C-283 JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 310 OP 318 VO 11 IS 3 A1 MAREK GNIAZDOWSKI A1 LESZEK SZMIGIERO A1 KRYSTYNA ŚLASKA A1 BARBARA JAROS-KAMIŃSKA A1 EWA CIESIELSKA YR 1975 UL http://molpharm.aspetjournals.org/content/11/3/310.abstract AB 1-Nitro-9,3-N,N-dimethylaminopropylaminoacridine (C-283) is of pharmacological interest as a potent inhibitor of tumor growth and RNA synthesis in vivo. Its effect on RNA synthesis directed by Escherichia coli RNA polymerase is strongly influenced by sulfhydryl compounds. Its maximal inhibitory effect requires simultaneous mixing of a sulfhydryl compound, such as mercaptoethanol, dithiothreitol, or α-thioglycerol, with DNA and drug at pH 8.0 prior to addition of the enzyme. Very slight inhibition was observed with the nitroacridine in the absence of a thiol. The influence of sulfhydryl compounds has been ascribed to reaction of the template with the 1-nitro group of the dye. Among the DNA-interacting dyes so far investigated, only 1-nitro analogues of C-283 enhance inhibition in the presence of sulfhydryl compounds. There are indications that the metabolite rather than the nitroacridine itself is responsible for the inhibitory effect in vivo. ACKNOWLEDGMENTS We wish to thank Dr. W. Ciesielcki for his help in infrared spectra determinations and their discussion, Miss Małgorzata Affeltowicz for excellent technical assistance, and Mrs. Zofia Germarowa, Scientific Research Center of the Medical Academy, for radioactivity measurements.