Aryl nucleoside H-phosphonates. Part 15: Synthesis, properties and, anti-HIV activity of aryl nucleoside 5′-α-hydroxyphosphonates

Aryl nucleoside 5'-H-phosphonates 4 bearing AZT or 2',3'-dideoxyuridine moieties were subjected to reaction with various aromatic aldehydes to produce nucleoside 5'-alpha-hydroxyphosphonate derivatives 2 as potential anti-HIV agents. Stability of the title compounds in cell culture media was investigated and three distinct decomposition pathways were identified. The anti-HIV activity of hydroxyphosphonates 2 correlates well with the type and extent of their chemical or enzymatic degradation in culture medium (RPMI 1640 containing 10% FBS), suggesting that aryl nucleoside 5'-hydroxyphosphonates 2 act as depot forms of the parent antiviral nucleosides.

Synthesis and anticancer activities of amphiphilic 5-fluoro-2'-deoxyuridylic acid prodrugs

Amphiphilic anticancer prodrugs of 5'-fluoro-2'-deoxyuridine-5'-monophosphate (5-FdUMP) were synthesized according to the hydrogen phosphonate method by coupling lipophilic cytosine derivatives or a phospholipid with 5-fluoro-2'-deoxyuridine (5-FdU). Studies within the in vitro Anticancer Screen Program of the National Cancer Institute have demonstrated high anticancer activities of the heterodinucleoside phosphates: N4-palmitoyl-2'-deoxycytidylyl-(3' --> 5')-3'-O-acetyl-5-fluoro-2'-deoxyuridine (dC(pam)-5-FdU(Ac), N4-palmitoyl-2',3'-dideoxycytidylyl-(5' --> 5')-3'-O-acetyl-5-fluoro-2'-deoxyuridine (ddC(pam)-(5' --> 5')-5-FdU(Ac), 5-fluoro-2'-deoxyuridylyl-(3' --> 5')-5-fluoro-N4-hexadecyl-2'-deoxycytidine (5-FdU-5-FdC(hex)), and of the new liponucleotide 1-O-octadecyl-rac-glycerylyl-(3 --> 5')-5-fluoro-2'-deoxyuridine (Oct1Gro-(3 --> 5')-5-FdU). The anticancer activities of these prodrugs are comparable to those of 5-FdU and the tumor specificities are modulated by their structures. The highest cytotoxic activity being even superior to 5-FdU was expressed by the dimer 5-FdU-5-FdC(hex).

Synthesis, in vitro anti-HIV and anti-hepatitis B activities and pharmacokinetic properties of amphiphilic heterodinucleoside phosphates containing ddC and AZT

Amphiphilic heterodinucleoside phosphates containing AZT and ddC as antiviral monomer were synthesized according to the hydrogenphosphonate method and evaluated in vitro against HIV. dT-N4-pamddC was the most active (IC50 = 40 microM, EC50 = 80 nM) and least toxic (TI = 524) dimer and it exhibited also strong antiviral effects against eight AZT-resistant HIV strains. The ddC-containing heterodimers additionally inhibited HBV replication by 50-80% at 50 microM in Hep G2 2.2.15 cells.

Liposomes as drug delivery system: a strategic approach for the treatment of HIV infection

As the number of individuals infected with human immunodeficiency virus (HIV) is growing dramatically throughout the world, it is important to develop strategies to improve the treatment of this deadly disease. It is now well established that macrophages play a central role in HIV pathogenesis, acting as reservoirs for dissemination of virus throughout the immune system. As liposomes are naturally taken up by cells of the mononuclear phagocytic system, liposome-based therapy represents a convenient approach to improve the delivery of anti-HIV agents into infected cells improving thereby the efficacy of drugs and reducing their adverse side-effects. A more specific targeting of HIV-infected cells could also be obtained by using liposomes bearing surface attached-antibodies. This review details the applications of liposomes as drug carriers for the treatment of AIDS. It also gives an overlook of the different strategies that could be explored to control the progression of the disease in infected individuals.

In vitro anti-human immunodeficiency virus and anti-hepatitis B virus activities and pharmacokinetic properties of heterodinucleoside phosphates containing AZT or ddC

In vitro activities, against human immunodeficiency virus (HIV)- and hepatitis B virus (HBV)-infected cells, of four amphiphilic heterodinucleoside phosphates containing 3'-azido-2',3'-dideoxythymidine (AZT) or 2',3'-dideoxycytidine (ddC) as antiviral monomers were evaluated. The four compounds were N4-hexadecyl-2'-deoxyribocytidylyl-(3'-->5')-3'-azido-2',3'-deoxyt hymidine (N4-hxddC-AZT), N4-palmitoyl-2'-deoxyribocytidylyl-(3'-->5')-3'-azido-2',3'-deoxyt hymidine (N4-pamdC-AZT), N4-hexadecyl-2'-deoxycytidylyl-(3'-->5')-2',3'-dideoxycytidine (N4-hxddC-ddC) and 2'-deoxythymidylyl-(3'-->5')-N4-palmitoyl-2',3'-dideoxycytidine (dT-N4-pamddC). All four dimers were active against HIV, dT-N4-pamddC being the most active and least toxic. dT-N4-pamddC also exhibited strong antiviral effects against a panel of eight AZT-resistant HIV strains. The ddC-containing heterodimers incorporated in liposomes additionally inhibited HBV replication by 50-80% in HepG2 2.2.15 cells. AZT and the AZT-containing dimers were ineffective. Differences in pharmacokinetic properties between the antiviral monomers and the heterodimers were evaluated using liposomal formulations of 3H-labelled AZT heterodimers as model compounds. The cellular distribution of AZT in H9 cells was predominantly cytoplasmic, whereas the amphiphilic dimers were distributed more evenly throughout the cytoplasm, nuclear membranes and microsomes. Blood levels of the heterodimers decreased at a rate two- to threefold slower than AZT and the areas-under-the-curves were five- to sevenfold higher for N4-pamdC-AZT and N4-hxddC-AZT, respectively. Compared to AZT, the peak levels of the dimers were three to four times higher in blood and five to six times higher in the liver. Analysis of blood samples showed that 34% of N4-pamdC-AZT was metabolized to AZT, whereas only 9% of N4-hxddC-AZT released AZT. Considering the antiviral potency and the favourable pharmacokinetic properties of the heterodimers, these compounds merit further exploration as antiviral drugs.

Anti-human immunodeficiency virus type 1 activities of dideoxynucleoside phosphotriester derivatives in primary monocytes/macrophages

Mononucleoside phosphotriester derivatives of dideoxynucleosides, following intracellular enzymatic activation, are likely to liberate their parent 5'-nucleoside monophosphate. Prodrugs of 3'-azido-2',3'-dideoxythymidine (AZT), 2',3'-didehydro-2',3'- dideoxythymidine (d4T), 2',3'-dideoxyinosine (ddl) and 2',3'-dideoxyadenosine (ddA) were evaluated for their anti-HIV1 activities in monocyte-derived macrophages, cells which are known to have low levels of nucleoside kinases. Prodrugs were found to be much more active, or just as active, as the corresponding dideoxynucleoside. Furthermore, their selectivity index was enhanced by a factor of 2 to 200.