Synthesis and biological evaluation of novel saccharin derivatives containing 1,2,3-triazole moiety

Synthesis, Anticancer, Antioxidant, Anti-Inflammatory, Antimicrobial Activities, Molecular Docking, and DFT Studies of Sultams Derived from Saccharin

A series of N-substituted saccharins namely 2-(1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl) acetonitrile (2) and (alkyl 1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl) acetate (3a-g) were synthesized, in moderate to excellent yields, from commercially available starting materials by two different approaches and their chemical structures were characterized by spectroscopic techniques (1H-NMR, 13C-NMR, IR, and MS). All the synthesized compounds were evaluated for their anti-inflammatory toward IL-6 and TNF-α, antioxidant, as well as their anticancer activities against hepatic cancer cells. In addition, their anti-fungal and antibacterial activities against both Gram-positive and Gram-negative bacteria were tested. All the tested compounds have exhibited excellent (3a, d, e) to moderate anti-inflammatory activity. Additionally, esters (3b, f) and nitrile (2) showed excellent antioxidant activity. Furthermore, ester 3f, with isopropyl ester, exhibited the highest cytotoxic activity compared to the other esters. Moreover, all compounds were evaluated as selective inhibitors of the human COX-1 enzyme using molecular docking by calculating the free energy of binding, inhibition constant, and other parameters to find out the binding affinity. The molecular study showed that esters (3d, f) and nitrile (2) revealed the highest binding affinities, hence enhancing the inhibition activity with the active site of the COX-1 enzyme. All the tested compounds have more negative Gibbs free, electrostatic, and total intermolecular energies than the standard inhibitor ASA. These results indicate that, all the tested sultams are potent anti-inflammatory drugs as compared to standard inhibitors. Finally, the chemical properties and the quantum factors of synthesized sultams were calculated based on density functional theory (DFT) to predict reactivity, and then correlated with the experimental data. Ester 3f showed the lowest ionization potential and lowest energy gap (Egap = 7.5691 eV), which was correlated with its cytotoxic activity. Furthermore, the spatial electron distribution of HOMO, LUMO were computed and it clearly indicates the electron donation ability of all the tested compounds.

Design, synthesis, and structure-activity relationships of novel imidazo[4,5-c]pyridine derivatives as potent non-nucleoside inhibitors of hepatitis C virus NS5B

The hepatitis C virus (HCV) NS5B polymerase is an attractive target for the development of novel and selective inhibitors of HCV replication. In this paper, the design, synthesis, and preliminary SAR studies of novel inhibitors of HCV NS5B polymerase based on the structure of tegobuvir have been described. The efforts to optimize the antiviral potency and reduce the treatment side effects with respect to genotype 1b resulted in the discovery of compound 3, which exhibited an EC₅₀ of 1.163 nM and a CC₅₀ >200 nM in a cell-based HCV replicon system assay. Additionally, testing for inhibition of the hERG channel showed a marked improvement over tegobuvir and the pharmacokinetic properties of compound 3 indicated that it was worthy of further investigation as a non-nucleoside inhibitor of HCV NS5B polymerase.

Exploring the Photophysical and Photochemical Properties of N-(Thioalkyl)-saccharins as an Alternative Route to the Synthesis of Tricyclic Sultams

Photocyclization of N-(thioalkyl)-saccharin was carried out to obtain different polycyclic sultams in good yields. These photoreactions were efficient under inert atmosphere and acetone triplet-sensitized conditions indicating that the triplet excited state is directly involved in the formation of annulated products. The presence of molecular oxygen changes product distribution, and only photo-oxygenation products (sulfoxides and sulfones) were found. This result is especially valuable since, by simple changing from nitrogen- to oxygen-saturated solvent conditions, the reaction outcome can be tuned from cyclized to sulfur oxidation products. Additionally, steady-state photolysis, electrochemistry, and laser time-resolved spectroscopic studies confirmed that these reactions mainly proceeded by intramolecular electron transfer (ET) between the triplet excited saccharin moiety and sulfur atom.