Synthesis and Biological Evaluation of 5′-O-Fatty Acyl Ester Derivatives of 3′-Fluoro-2′,3′-dideoxythymidine as Potential Anti-HIV Microbicides

A number of 5′-O-fatty acyl derivatives of 3′-fluoro-2′,3′-dideoxythymidine (FLT, 1) were synthesized. These conjugates were evaluated for their potential as topical microbicides with anti-HIV activity against cell-free (X4 and R5), cell-associated, and multidrug-resistant viruses. Compared to FLT and 3′-azido-2′,3′-dideoxythymidine (AZT), 5′-O-(12-azidododecanoyl) (5), 5′-O-myristoyl (6), and 5′-O-(12-thioethyldodecanoyl) (8) derivatives of FLT were found to be more active against both cell-free viruses (lymphocytotropic and monocytotropic strains) with EC50 values of 0.4 μM, 1.1 μM, and \u3c0.2 μM, respectively, as well as cell-associated virus with EC50 values of 12.6, 6.4, and 2.3 μM, respectively. Conjugates 5, 6, and 8 exhibited \u3e4 and \u3e30 times better antiviral index than FLT and AZT, respectively. Conjugates 5 and 8 were significantly more potent than FLT against many multidrug-resistant strains. A comparison of the anti-HIV activity with the corresponding non-hydrolyzable ether conjugates suggested that ester hydrolysis to FLT and fatty acids is critical to enable anti-HIV activity. Cellular uptake studies were conducted using fluorescent derivatives of FLT attached with 5(6)-carboxyfluorescein through either β-alanine (23) or 12-aminododecanoic acid (24) spacers. The lipophilic fluorescent analog with a long chain (24) showed more than 12 times higher cellular uptake profile than the fluorescent analog with a short chain (23). These studies further confirmed that the attachment of fatty acids improved the cellular uptake of nucleoside conjugates. In addition, 5, 6, and 8 were the least cytotoxic and did not alter vaginal cell and sperm viability compared to the positive control, a commercial topical spermicide (N-9), which significantly decreased sperm and vaginal cell viability inducing the generation of proinflammatory cytokines

Preparation of E-1,3-diaminoethenyl functional groups by the reaction of enol tosylate of alpha-formylglycine with primary and secondary amines

The E-1,3-diaminoethenyl functional group is a potentially useful synthon. A number of examples of E-1,3-diaminoethenyl functional groups were prepared in good yield starting from an E-enol tosylate of a serine based diketopiperazine and 1°- or 2° amine nucleophiles. The reaction proceeds via a stereoselective nucleophilic substitution pathway

Emtricitabine Prodrugs with Improved Anti-HIV Activity and Cellular Uptake

Three fatty acyl conjugates of (−)-2′,3′-dideoxy-5-fluoro-3′-thiacytidine (FTC, emtricitabine) were synthesized and evaluated against HIV-1 cell-free and cell-associated virus and compared with the corresponding parent nucleoside and physical mixtures of FTC and fatty acids. Among all the compounds, the myristoylated conjugate of FTC (<b>5</b>, EC₅₀ = 0.07–3.7 μM) displayed the highest potency. Compound <b>5</b> exhibited 10–24 and 3–13-times higher anti-HIV activity than FTC alone (EC₅₀ = 0.7–88.6 μM) and the corresponding physical mixtures of FTC and myristic acid (<b>14</b>, EC₅₀ = 0.2–20 μM), respectively. Cellular uptake studies confirmed that compound <b>5</b> accumulated intracellularly after 1 h of incubation and underwent intracellular hydrolysis in CCRF-CEM cells. Alternative studies were conducted using the carboxyfluorescein conjugated with FTC though β-alanine (<b>12</b>) and 12-aminododecanoic acid (<b>13</b>). Acylation of FTC with a long-chain fatty acid in <b>13</b> improved its cellular uptake by 8.5–20 fold in comparison to <b>12</b> with a short-chain β-alanine. Compound <b>5</b> (IC₉₀ = 15.7–16.1 nM) showed 6.6- and 35.2 times higher activity than FTC (IC₉₀ = 103–567 nM) against multidrug resistant viruses B-NNRTI and B–K65R, indicating that FTC conjugation with myristic acid generates a more potent analogue with a better resistance profile than its parent compound

Collaborative Study to Validate Purity Determination by ¹H Quantitative NMR Spectroscopy by Using Internal Calibration Methodology

n/

A community-built calibration system: The case study of quantification of metabolites in grape juice by qNMR spectroscopy

Nuclear Magnetic Resonance (NMR) is an analytical technique extensively used in almost every chemical laboratory for structural identification. This technique provides statistically equivalent signals in spite of using spectrometer with different hardware features and is successfully used for the traceability and quantification of analytes in food samples. Nevertheless, to date only a few internationally agreed guidelines have been reported on the use of NMR for quantitative analysis. The main goal of the present study is to provide a methodological pipeline to assess the reproducibility of NMR data produced for a given matrix by spectrometers from different manufacturers, with different magnetic field strengths, age and hardware configurations. The results have been analyzed through a sequence of chemometric tests to generate a community-built calibration system which was used to verify the performance of the spectrometers and the reproducibility of the predicted sample concentrations