SBIR-STTR Award

Use of nucleoside phosphates as antitumor and antiviral agents has been limited by their inability to penetrate cell membranes as well as their high susceptibility to enzymes such as phosphatases, nucleotidases, etc. Modification of the phosphate group (by replacing one of the nonbridging oxygens with a borane group) may provide both the membrane permeability to these compounds and the stability (towards phosphate-removing enzymes). The long-term objective of this project is to synthesize nucleoside mono-, di- and triphosphates in which one of the oxygens of a, B or r phosphorus has been replaced with an isoelectronic borane group. These compounds may be prepared by phosphorylation of nucleosides, nucleoside monophosphates and nucleoside diphosphates using a boronated phosphorylating agent. In our studies with related oligonucleotide boranophosphates, the P-BH3 moiety has been found to be remarkably stable and the oligonucleotide boranophosphates have high nuclease resistance. The nucleoside boranophosphates may be useful in a number of ways including1) as tools for studying mechanism of action of enzymes,2) as antiviral and antitumor agents, and3) as carriers of boron for boron neutron capture therapy.Awardee's statement of the potential commercial applications of the research:Nucleoside boranophosphates may be valuable as tools for studying enzymatic processes in basic research. They may prove to be conunercially valuable as antitumor and antiviral drugs. In addition, they may be valuable in boron neutron capture therapy.National Institute of Allergy and Infectious Diseases (NIAID)

Ribo- and deoxyribonucleoside 5'-mono-, di-, and triphosphates play key roles in the metabolism of nucleic acids. Analogues in which a non- bridging oxygen is replaced with another group can serve to not only provide fundamental information on the mechanism of important enzymatic reactions, but control such reactions for medical and pharmacological purposes. In Phase I, synthetic routes were successfully developed to prepare nucleoside phosphate analogues in which a borane group was attached to phosphorus. Replacement of a non-bridging oxygen with an isoelectronic BH3 gives a similarly charged moiety (P-~>PBH3-), but one which cannot coordinate to metal ions nor hydrogen bond and is more lipophilic. Thymidine and adenosine-5'-borano-monophosphate and a thymidine-5'-alpha-boranotriphosphate were prepared. The boronated thymidine triphosphate was found to substitute for the normal dTTP in a DNA polymerase experiment. Thymidine 5'-boranophosphate is a substrate of acid phosphatase unlike thymidine 5'-thiophosphate, indicating complementary uses to probe details of enzymic reactions. Cytotoxicity in tumor screens has been found. The Phase 11 effort involves the preparation of a variety of nucleoside 5'-mono-, di-, and triphosphates with borane substitution on phosphorus. Modified boronated nucleotides with greater lipophilicity will be prepared to produce enhanced concentrations of the free boronated nucleotide inside cells for pharmacological potency. Extensive enzymatic studies will be carried out to biochemically define these novel species. Cytotoxicity against tumor lines and antiviral activity will be determined.Awardee's statement of the potential commercial applications of the research: Nucleoside boranophosphates may serve as valuable tools for studying enzymic processes at the molecular level. T hey (especially the more lipophilic derivatives) may be commercially valuable as antitumor and antiviral agents. Additionally, the boronated nucleoside phosphates may act as carriers of boron-10 to tumor tissue for boron neutron capture therapy.National Institute of Allergy and Infectious Diseases (NIAID)