Synthesis and Biochemical Evaluation of 5-Tethered Boron-Containing Pyrimidine Nucleosides for BNCT
In order for BNCT to be successful, a major need is the development of boron compounds, which penetrate the blood-brain barrier (BBB), target tumor cells selectively, and maintain a relatively high concentration of boron-10 in the tumor, ca. 30 ug/g of tumor tissue, vis-à-vis surrounding normal tissues. Boron-containing nucleosides that use a carrier-mediated transport process for penetrating the CNS and have the potential for becoming incorporated into proliferating cells may be useful agents for BNCT.1 This fact led to the attempts to synthesize carborane-containing nucleoside derivatives. Yamamoto2 and Schinazi3 have attached the carborane moiety to the 5-position on the pyrimidine nucleosides, either directly or through a bulky substituent. Unfortunately, these compounds are very poor substrates for nucleoside kinases, and are unlikely to demontrate the requisite biological activity. This may be due to the fact that having a bulky substituent, like the carborane moiety, attached directly on the 5-position may inhibit enzymatic conversion of the 5-carboranyl-2′-deoxyuridine to their corresponding nucleotides. The formation of the latter is a necessary precondition for the incorporation of such nucleotides into DNA.
KeywordsThymidine Kinase Bulky Substituent Boron Compound Pyrimidine Nucleoside Amine Hydrochloride
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- 1.I. M. Wyzlic, W. Tjarks, A. H. Soloway, A. K. M. Anisuzzaman, F.-G. Rong and R. F. Barth, Strategies for the design and synthesis of boronated nucleic acid and protein components as potential delivery agents for neutron capture therapy, Int. J. Radiation Oncology Biol. Phys., 28: 1203–1213, 1994.CrossRefGoogle Scholar
- 2.Y. Yamamoto, T. Seko, F.-G. Rong and H. Nemoto, A new synthetic method via condensation with aldehydes having boronic moiety,Tetra. Lett., 30: 7191–7194, 1989.Google Scholar
- 4.C. R. Lowe and P. D. G. Dean, Spacer molecules and steric considerations, in “Affinity Chromatography”, Wiley-Interscience, John Wiley & Sons: London, 1974, pp 23–32.Google Scholar