Synthesis and anti-HIV activities of bis-(cycloSaligenyl) pronucleotides derivatives of 3'-fluoro-3'-deoxythymidine and 3'-azido-3'-deoxythymidine

Design, synthesis, antiviral activity, and pre-formulation development of poly-L-arginine-fatty acyl derivatives of nucleoside reverse transcriptase inhibitors

The objective of this work was to design conjugates of anti-HIV nucleosides conjugated with fatty acids and cell-penetrating poly-L-arginine (polyArg) peptides. Three conjugates of polyArg cell-penetrating peptides with fatty acyl derivatives of alovudine (FLT), lamivudine (3TC), and emtricitabine (FTC) were synthesized. In general, the compounds exhibited anti-HIV activity against X4 and R5 cell-free virus with EC50 values of 1.5-16.6 μM. FLT-CO-(CH2)12-CO-(Arg)7 exhibited EC50 values of 2.9 μM and 3.1 μM against X4 and R5 cell-free virus, respectively. The FLT conjugate was selected for further preformulation studies by determination of solution state degradation and lipid solubility. The compound was found to be stable in neutral and oxidative conditions and moderately stable in heated conditions.

Design and synthesis of novel distamycin-modified nucleoside analogues as HIV-1 reverse transcriptase inhibitors

Design and synthesis of nucleoside analogues have persistently attracted extensive interest because of their potential application in the field of antiviral therapy, and its study also receives additional impetus for improvement in the ProTide technology. Previous studies have made great strides in the design and discovery of monophosphorylated nucleoside analogues as potential kinase-independent antiretrovirals. In this work, a series of nucleoside phosphoramidates modified by distamycin analogues was synthesized and evaluated as nucleoside reverse transcriptase inhibitors (NRTIs) in HIV-1-infected MT-4 and CEM cells, including variations in nucleoside, alkyl moiety, and the structure of distamycin analogues. These compounds exhibited modest potency with the EC50 value in the range of 1.3- to 6.5-fold lower than their corresponding parent drugs in MT-4 cells, which may be attributed to increasing intracellular availability due to the existence of distamycin analogue with favorable hydrophilic-lipophilic equilibrium. Meanwhile, the length of distamycin analogue was considered and assessed as an important factor that could affect antiviral activity and cytotoxicity. Enzymatic and metabolic stability studies have been performed in order to better understand the antiviral behavior of these compounds. The present work revealed the compounds to have a favorable and selective anti-HIV-1 activity in MT-4 and CEM cells, and helped to develop strategies for design and synthesis of effective monophosphorylated nucleoside analogues, which may be applied to antiretroviral research as NRTIs.

Synthesis and anti-HIV activities of glutamate and peptide conjugates of nucleoside reverse transcriptase inhibitors

Mono-, di-, and trinucleoside conjugates of glutamate or peptide scaffolds containing nucleoside reverse transcriptase inhibitors were synthesized. Among dinucleoside glutamate ester derivatives, N-myristoylated derivatives showed significantly higher anti-HIV activity than the corresponding N-acetylated conjugates against cell-free virus. Myristoyl-Glu(3TC)-FLT (46, EC(50) = 0.3-0.6 μM) and myristoyl-Glu(FTC)-FLT (47, EC(50) = 0.1-0.4 μM) derivatives were the most active glutamate-dinucleoside conjugates. A trinucleoside glutamate derivative containing AZT, FLT, and 3TC (34, EC(50) = 0.9-1.4 μM) exhibited higher anti-HIV activity than AZT and 3TC against cell-free virus. Compound 34 also exhibited higher anti-HIV activity against multidrug (IC(50) = 5.9 nM) and NNRTI (IC(50) = 12.9 nM) resistant viruses than parent nucleosides. The physical mixture containing FLT-succinate, AZT, 3TC, and glutamic acid exhibited 115-fold less activity against cell associated virus (EC(50) = 91.9 μM) when compared to 34 (EC(50) = 0.8 μM). Other conjugates showed less or comparable potency to that of the corresponding physical mixtures.

Synthesis and biological evaluation of fatty acyl ester derivatives of 2',3'-didehydro-2',3'-dideoxythymidine

A number of 5'-O-fatty acyl derivatives of 2',3'-didehydro-2',3'-dideoxythymidine (stavudine, d4T) were synthesized and evaluated for anti-HIV activities against cell-free and cell-associated virus, cellular cytotoxicity, and cellular uptake studies. The conjugates were found to be more potent than d4T. Among these conjugates, 5'-O-12-azidododecanoyl derivative of d4T (2), displaying EC(50) = 3.1-22.4 μM, showed 4- to 9-fold higher activities than d4T against cell-free and cell-associated virus. Cellular uptake studies were conducted on CCRF-CEM cell line using 5(6)-carboxyfluorescein derivatives of d4T attached through β-alanine (9) or 12-aminododecanoic acid (10) as linkers. The fluorescein-substituted analog of d4T with long chain length (10) showed 12- to 15-fold higher cellular uptake profile than the corresponding analog with short chain length (9). These studies reveal that conjugation of fatty acids to d4T enhances the cellular uptake and anti-HIV activity of stavudine.