VOL. 32 (1959) PRELIMINARY NOTES 295 Synthesis and biological activities of iododeoxyuridine, an analog of thymidine Iodinated derivatives of uracil and of uracil-containing compounds have been synthesized previously and some of their biological activities investigated z, 2. Whereas 5-iodouracil has been shown to be an effective inhibitor of microbial growth S and to be readily incorporated into the deoxyribonucleic acids of several microbial species s, 4, 5-iodouridine and 5-iodoorotic acid were biologically inert in the systems which were investigated 1. These studies have been extended by the present report to the corre- sponding iodinated deoxyribonucleoside. 5-Iododeoxyuridine was synthesized by a modification of the method described previously for the synthesis of 5-iodouridine 1. Uracildeoxyriboside (400 mg), iodine (40o rag), chloroform (2 ml) and HNO s (I N, 4 ml) were refluxed gently for 2 h during which time white needle crystals of iododeoxyuridine formed. The reaction mixture was decanted into a sintered-glass funnel and the product was washed with ether until the unreacted iodine had been extracted. After recrystallization from hot water the yield was 350 mg or 56 % of theory. Analysis. Found: C, 30.46; H, 2.95; N, 8.05; I, 35,45; Calc. for CgHnOsN2I: C, 3o.5I; H, 3.11; N, 7.91; I, 35.88. Decomposition occurred at 16o ° and fumes of iodine appeared at 18o ° . The u.v.-absorption characteristics of several iodinated pyrimidines and their parent compounds are shown in Table I. TABLE I ULTRAVIOLET ABSORPTION MAXIMA AND MINIMA OF SOME DERIVATIVES OF URACIL AND IODOURACIL Compound NaOH (o.o1 N) HCl(o.o2 N) max. rain. max. rain. m/* ml* m~ m~ Iodouracil 304 256 283 245 Uracil 284 241 259 227 Iodouridine 278 253 289 249 Uridine 262 236 262 230 Iododeoxyuridine 278 253 288 248 Deoxyuridine 262 242 262 231 The u.v.-absorption spectrum of the synthetic iododeoxyuridine agrees with that of material isolated from microbial DNA by ZAMENHOF et al. 3 and by DUNN AND SMITH 4. FRIEDKIN AND ROBERTS 5 presented evidence for the formation of iododeoxy- uridine by a mammalian enzyme, but no characterisation was given. The insertion of the iodine atom into each pyrimidine derivative results in a bathochromic effect; however, in alkaline solution the u.v. maximum for iodouracil shifts to a longer wave- length, whereas the corresponding riboside and deoxyriboside shift to a lower wave- length. The non-iodinated nucleosides in alkali show no shift in their absorption maxima. The iodinated derivatives are readily separated from the parent compound and Abbreviations: DNA, deoxyribonucleic acid; RNA, ribonucleic acid,
`
`IPR2018-00120
`
`Page 1 of 2
`
`I-MAK 1011
`
`

`

`296 PRELIMINARY NOTES VOL. 32 (1959) from each other by paper chromatography employing the ethyl acetate-phosphate buffer system 6 (Table II). Insertion of the iodine atom into the molecule results in a marked increase in the mobility of each of the pyrimidine derivatives; however, there is no alteration in the order of migration. Iododeoxyuridine may also be synthesized by a modification of the method of JOHNSON AND JOHNS 7 for iodouracil. Deoxyuridine (228 mg), iodine (250 mg), and NaOH (3 N, 2 ml) were heated on a steam bath for 15 min; after dilution with water (50 ml) the solution was passed through a Dowex-I-formate column. After washing the column with NaOH (o.oi N) until no iodide appeared in the effluent, as indicated by reaction with AgN08, elution was continued with formic acid (o.I N). Immediately after the elution of unreacted deoxyuridine, iododeoxyuridine appeared. TABLE Ii RF VALUES OF SOME DERIVATIVES OF URACIL AND IODOURACIL Solvent: Ethyl acetate saturated with phosphate buffer (o.o5 M, pH 6.0). Compound R F Iodouracil o. 75 Uracil o. 21 Iododeoxyuridine 0.67 Deoxyuridine o. i 2 Iodouridine 0.44 Uridine 0.06 In contrast to iodouridine, iododeoxyuridine is almost as effective as iodouracil as an inhibitor of the growth of Streptococcus [aecalis (ATCC 8o43), when grown in media supplemented with thymine, thymidine or pteroylglutamic acid. With mouse Ehrlich ascites carcinoma cells in vitro, iododeoxyufidine but not iodouracil or iodouridine reversibly inhibited the utilization of 14C-labeled thymidine for the bio- synthesis of DNA-thymine. Iododeoxyuridine inhibited markedly the utilization of [14C]orotic acid or [a4C]forrnate for the biosynthesis of DNA-thymine, but not of [a4C] orotic acid for the biosynthesis of DNA-cytosine or RNA pyrimidines. Hence the mechanism of action of iododeoxyuridine would appear to be an inhibition of the utilization of a thymine-containing precursor of DNA-thymine. Details of the bio- logical studies will appear elsewhere. This investigation was supported by a grant (CY-3o76) from the National Institutes of Health, U.S. Public Health Service. Department o~ Pharmacology Yale University, School o/ Medicine, New Haven, Conn. (U.S.A.) WILLIAM H. PRUSOFF 1 w. H. PRUSOFF, W. L. HOLMES AND A. D. WELCH, Cancer Research, 13 (1953) 22i. 2 G. H. HITCHINGS, E. A. FALCO AND M. B. SHI~RWOOD, Science, lO2 (1945) 251. 8 S. ZAMENHOF, B. RlglNER, R. DEGIOVANNI AND K. RICH, J. Biol. Chem., 219 (1956) 165. 4 D. B, DUNN AND J. D. SMITH, Biochem. J., 67 (1957) 494; Nature, 174 (1954) 305. 5 M. FRIEDKIN AND D. ROBERTS, J. Biol. Chem., 2o 7 (1954) 257. * W. H. PRUSOFF, J. Biol. Chem., 215 (1955) 809. 7 T. B. JohNsoN AND C. O. JOHNS, J. Biol. Chem., I (I905-O6) 305 . Received November 2oth, 1958
`
`IPR2018-00120
`
`Page 2 of 2
`
`I-MAK 1011
`
`