Inhibition of HIV-1 replication in macrophages by red blood cell-mediated delivery of a heterodinucleotide of azidothymidine and 9-(R)-2-(phosphono methoxypropyl)adenine.

Monocyte-derived macrophages (M/M) are considered important in vivo reservoirs for different kinds of viruses, including HIV. Hence, therapeutic strategies are urgently needed to protect these cells from virus infection or to control viral replication. In this paper, we report the synthesis, target delivery and in vitro efficacy of a new heterodinucleotide (AZTpPMPA), able to inhibit HIV-1 production in human macrophages. AZTpPMPA consists of two established anti-HIV drugs [zidovudine (AZT) and tenofovir (PMPA)] chemically coupled together by a phosphate bridge. This drug is not able to prevent p24 production when administered for 18 h to M/M experimentally infected with HIV-1 Bal (inhibition 27%), but can almost completely suppress virus production when given encapsulated into autologous erythrocytes (inhibition of p24 production 97%). AZTpPMPA is slowly converted to PMPA, AZT monophosphate and AZT (36 h half-life at 37°C) by cell-resident enzymes. Thus AZTpPMPA should be considered a new prodrug of AZT and PMPA that is able to provide stechiometric amounts of both nucleoside analogues to macrophage cells and to overcome the low phosphorylating activity of M/M for AZT and the modest permeability of PMPA

5'-C-ethyl-tetrazolyl-N 6-substituted adenosine and 2-chloro-adenosine derivatives as highly potent dual acting A1 adenosine receptor agonists and A3 adenosine receptor antagonists

A series of N(6)-substituted-5'-C-(2-ethyl-2H-tetrazol-5-yl)-adenosine and 2-chloro-adenosine derivatives was synthesized as novel, highly potent dual acting hA1AR agonists and hA3AR antagonists, potentially useful in the treatment of glaucoma and other diseases. The best affinity and selectivity profiles were achieved by N(6)-substitution with a 2-fluoro-4-chloro-phenyl- or a methyl- group. Through an in silico receptor-driven approach, the molecular bases of the hA1- and hA3AR recognition and activation of this series of 5'-C-ethyl-tetrazolyl derivatives were explained

Synthesis and potency of novel uracil nucleotides and derivatives as P2Y2 and P2Y6 receptor agonists

The phosphate, uracil, and ribose moieties of uracil nucleotides were varied structurally for evaluation of agonist activity at the human P2Y2, P2Y4, and P2Y6 receptors. The 2-thio modification, found previously to enhance P2Y2 receptor potency, could be combined with other favorable modifications to produce novel molecules that exhibit high potencies and receptor selectivities. Phosphonomethylene bridges introduced for stability in analogues of UDP, UTP and uracil dinucleotides markedly reduced potency. Truncation of dinucleotide agonists of the P2Y2 receptor, in the form of Up4-sugars, indicated that a terminal uracil ring is not essential for moderate potency at this receptor and that specific SAR patterns are observed at this distal end of the molecule. Key compounds reported in this study include: 9, α,β-methylene-UDP, a P2Y6 receptor agonist; 30, Up4-phenyl ester and 34, Up4-[1]glucose, selective P2Y2 receptor agonists; 43, the 2-thio analogue of INS37217 (P1-(uridine 5′)-P4- (2′-deoxycytidine 5′) tetraphosphate), a potent and selective P2Y2 receptor agonist

Synthesis and antitumor activity of a heterodinucleotide of BVDU and Gemcitabine

A heterodinucleotide comprising BVDU and Gemcitabine bound together by a 5',5'-pyrophospate bridge (BVDUp(2)dFdC) has been synthesized and evaluated as antitumor agent against AH13 rat sarcoma cells. BVDUp(2)dFdC showed a cytotoxicity similar to that of Gemcitabine

Dual-target dimeric molecules with antitumor properties. Synthesis and biological activity of 3’-C-methyladenosine-valproates

In recent years, together with development of new antitumor drugs, significant efforts have been directed toward the development of combination therapies in the treatment of different types of cancers. Some enzymes that play vital roles in DNA replication and transcription, such as ribonucleotide reductase (RR) and histone deacetylases (HDACs), are attractive targets for cancer chemotherapy. Many drugs exert their cytotoxic effects through inhibition of these enzymes’ activity. Moreover, several reports have suggested that HDAC inhibitors (HDACi) synergize with anticancer agents directed at other targets. Valproic acid (VPA), a short branched fatty acid used for the treatment of epilepsy, has emerged as a promising drug for cancer treatment showing antineoplastic activities against both solid and hematologic malignancies mediated by HDACs inhibition. A phase II multicenter study reported that the combination of VPA with 5-azacytidine, a DNA-methyltransferase inhibitor, is active and safe in patients with myelodysplastic syndromes (MDS) with a poor prognosis. In addition, the combination of VPA with either fludarabine or cladribine, two purine nucleoside analogues acting as RR allosteric inhibitors, greatly increased apoptosis in chronic lymphocitic leukaemia (B-CLL) cells. Even more interestingly, VPA induced apoptosis in poor prognosis patients resistant to different type of chemotherapy. In our previous work we found that 3’-C-methyl-adenosine (3’-Me-Ado),1 developed by us as a potent RR inhibitor with antitumor activity against both human leukaemia and carcinoma cell lines, has significant growth inhibitory and apoptotic synergistic effects in HL60 and NB4 promyelocytic leukaemia cells in combination with some hydroxamic acid–derived HDAC inhibitors2. On the basis of this result, we pursued the development of dual-target drugs by combining the structures of 3’-Me-Ado and VPA in a single molecule. This approach has high potential to improve therapeutic efficacy of the single drug and to reduce the probability of drug induced resistance and cross resistance. The 3’-C-methyladenosine-5’-O-valproic ester and the 2’,5’-diester analog were synthesized and evaluated for their antitumor potential against a panel of human cancer cell lines. The results of this study will be presented. References: 1-FRANCHETTI, P., et al., 2005. Antitumor activity of C-methyl-β-D-ribofuranosyladenine nucleoside ribonucleotide reductase inhibitors. Journal of Medicinal Chemistry, 48, 4983-4989. 2-GRIFANTINI, M., et al., 2009. Histone deacetylase (HDAC) inhibition modulates intracellular deoxynucleotides (DNTP) pools and potentiates the antitumor effects of the ribonucleotide reductase (RR) inhibitor 3’-methyl-adenosine (3’-Me-ADO) in promyelocitic leukaemia cell lines. 34° CONGRESSO NAZIONALE DELLA SOCIETÀ ITALIANA DI FARMACOLOGIA, P-2/4/16, Rimini, 14-17 Ottobre 2009

Stereoselective synthesis of nicotinamide β-riboside and nucleoside analogs

The beta-anomers of N-ribofuranosylnicotine-3-carboxamide (beta-NAR) and its nicotinic acid analog (beta-NaR) were obtained by stereoselective synthesis via glycosylation of the presilylated bases under Vorbruggen's protocol. A NAR analog, methylated in position 3 of the ribosylic moiety, is also reported