A. L. Khandazhinskaya

Anti-HIV therapy with AZT prodrugs: AZT phosphonate derivatives, current state and prospects

Importance of the field: AIDS, a disease caused by human immunodeficiency virus, was called ‘plague of the twentieth century’. 3′-Azido-3′-deoxythymidine (AZT), the first compound approved for the treatment of HIV, is still a mandatory component of treatment schemes. However, its toxicity stimulated a search for new agents. Areas covered in this review: This review presents the history and current state of the design of AZT prodrugs based on its phosphonate derivatives. What the reader will gain: Although every effort was made to include as many AZT structures bearing phosphonate residues and demonstrate the variety they offer, we also concentrated on the studies performed in our laboratory. Special attention was also paid to AZT 5′-H-phosphonate (phosphazide, Nikavir®) approved in the Russian Federation as a drug for the prevention and treatment of HIV infection. Take home message: The prodrug strategy applied to AZT phosphonate derivatives enriched chemistry, biology and medicine not only with new knowledge, methods and structures, but also with a new anti-HIV drug Nikavir. Currently, study of another phosphonate, AZT 5′-aminocarbonylphosphonate, is underway. Slow release of AZT following oral administration and penetration into cells, decreased toxicity and the lack of cumulative properties make the compounds of this group promising as extended-release forms of AZT.

ANTI-HIV ACTIVITY OF NOVEL PHOSPHONATE DERIVATIVES OF AZT, d4T, AND ddA

Anti-HIV activity and cytotoxicity were tested for novel phosphonate derivatives of AZT, d4T and ddA. For d4T phosphonate derivatives the most active was 2′,3′-Dideoxy-2′,3′-didehydrothymidine 5′-isopropylphosphite and among the AZT phosphonate derivatives highest activity was shown by 2′,3′-Dideoxy-3′-azidothymidine 5′-cyclohexylphosphite.

Incorporation of non-nucleoside triphosphate analogues opposite to an abasic site by human DNA polymerases β and λ

A novel class of non-nucleoside triphosphate analogues, bearing hydrophobic groups sterically similar to nucleosides linked to the α-phosphate but lacking the chemical functional groups of nucleic acids, were tested against six different DNA polymerases (polymerases). Human polymerases α, β and λ, and Saccharomyces cerevisiae polymerase IV, were inhibited with different potencies by these analogues. On the contrary, Escherichia coli polymerase I and HIV-1 reverse transcriptase were not. Polymerase β incorporated these derivatives in a strictly Mn++-dependent manner. On the other hand, polymerase λ could incorporate some alkyltriphosphate derivatives with both Mg++ and Mn++, but only opposite to an abasic site on the template strand. The active site mutant polymerase λ Y505A showed an increased ability to incorporate the analogues. These results show for the first time that neither the base nor the sugar moieties of nucleotides are required for incorporation by family X DNA polymerases.

New derivatives of alkyl-and aminocarbonylphosphonic acids containing 3′-azido-3′-deoxythymidine

New 5′-phosphonates of 3′-azido-3′-deoxythymidine were synthesized and shown to be low-toxic and markedly active in MT-4 cell cultures infected with HIV-1.

New Lipophilic Derivatives of AZT and d4T 5′-Phosphonates

Abstract 5′-Aminocarbonylphosphonyl and aminocarbonylmethylphosphonyl diesters of AZT and d4T were synthesized as potential anti-HIV agents.

New Nonnucleoside Substrates for Terminal Deoxynucleotidyl Transferase: Synthesis and Dependence of Substrate Properties on Structure

N-(9-Fluorenylmethoxycarbonyl)-ω-aminoalkyl-, N-(9-fluorenylmethoxycarbonyl)-8-amino-3,6-dioxaoctyl, and N-[(9-fluorenylmethoxycarbonyl)-6-aminohexanoyl]-2-aminoethyl triphosphates were synthesized. All of them were shown to be the substrates of the calf thymus terminal deoxynucleotidyl transferase. Their substrate properties depend on the length and structure of the linker between the 9-fluorenylmethoxycarbonyl and triphosphate moieties.

[New phosphonoformic acid derivatives of 3'-azido-3'-deoxythymidine].

New 5′-alkyl ethoxy- and aminocarbonylphosphonates of 3′-azido-3′-deoxythymidine (AZT) were synthesized, and their antiviral properties in HIV-1-infected cell cultures and stability to chemical hydrolysis were studied. The AZT 5′-aminocarbonylphosphonates were shown to be significantly more stable in phosphate buffer (pH 7.2) than the corresponding ethoxycarbonylphosphonates. The therapeutic (selectivity) index of some of the compounds exceeded that of the parent AZT due to their higher antiviral activity.

P-(alkyl)-nucleoside 5'-hydrogenphosphonates as depot forms of antiviral nucleotide analogues.

Abstract P-(Alkyl)esters of AZT 5′-hydrogenphosphonate were synthesized and their stabilities in the phosphate buffer and human serum were evaluated. The esters bearing residues of primary and secondary alcohols were degraded to give AZT, whereas those containing tertiary alkyl groups yielded AZT 5′-hydrogenphosphonate. The corresponding derivatives of d2A and d4T showed the same properties.

Aryl-Containing Esters Of Triphosphoric Acid As Substrates Of Terminal Deoxynucleotidyl Transferase

A new group of terminal deoxynucleotidyltransferase (TDT) substrates, namely, non-nucleoside triphosphates (NNTP) bearing 5-substituted 2,4-dinitrophenyl fragments instead of nucleoside residues was synthesized.

Synthesis of Novel Alkyl Triphosphates and Their Substrate Properties Toward Terminal Deoxynucleotidyltransferase

Novel triphosphate derivatives bearing bulky or small groups at α-position attached to the triphosphate residue through linkers of different structures and lengths were synthesized and studied as substrates toward terminal deoxynucleotidyltransferase. The substrate efficacy depends on the structure of substituents, linker length, and nature of metal activator. The replacement of hydrophobic groups by small substituents decreased the substrate efficacy by about 20 times in respect to hydrophobic residues. The dependence on metal activator is the following: Co2+ > Mn2+ >> Mg2+. The model of interaction of alkyl triphosphates with linkers of different lengths bearing TdT active site is presented.