Synthesis and Anti-HCV Activity of 4‑Hydroxyamino α‑Pyranone Carboxamide Analogues

High genetic variability in hepatitis C virus (HCV), emergence of drug resistant viruses and side effects demand the requirement for development of new scaffolds to show an alternate mechanism. Herein, we report discovery of new scaffold <b>I</b> based on 4-hydroxyamino α-pyranone carboxamide as promising anti-HCV agents. A comprehensive structure–activity relationship (SAR) was explored with several newly synthesized compounds. In all promising compounds (<b>17</b>–<b>19</b>, <b>21</b>–<b>22</b>, <b>24</b>–<b>25</b>, and <b>49</b>) with EC₅₀ ranging 0.15 to 0.40 μM, the aryl group at C-6 position of α-pyranone were unsubstituted. In particular, <b>25</b> demonstrated potential anti-HCV activity with EC₅₀ of 0.18 μM in cell based HCV replicon system with lower cytotoxicity (CC₅₀ > 20 μM) and provided a new scaffold for anti-HCV drug development. Further investigations, including biochemical characterization, are yet to be performed to elucidate its possible mode of action

Sequential Pd(0)/Fe(III) Catalyzed Azide–Isocyanide Coupling/Cyclization Reaction: One-Pot Synthesis of Aminotetrazoles

A rapid and efficient synthesis of aminotetrazole from aryl azides, isocyanides, and TMSN₃ is developed. The reaction is promoted by sequential Pd(0)/Fe­(III) catalysis. The reaction sequence utilizes the Pd-catalyzed azide–isocyanide denitrogenative coupling reaction to generate unsymmetric carbodiimide <i>in situ</i>, which reacts with TMSN₃ in the presence of FeCl₃ in a single pot. The methodology has distinct advantages over traditional synthetic approaches where toxic Hg and Pb salts are employed at stoichiometric scale

Stable Tricyclic Antitubercular Ozonides Derived from Artemisinin

New, highly stable tricyclic antitubercular ozonides <b>9</b> and <b>10</b> derived from artemisinin are reported in 39 and 9% yields, respectively. The ozonide groups of <b>9</b> and <b>10</b> were found to be stable under strong basic and acidic conditions. The absolute configuration of ozonides <b>9</b> was confirmed by X-ray crystallography. Ozonide <b>10</b> shows promising antitubercular activity against <i>M. tuberculosis</i> H₃₇Ra and <i>M. tuberculosis</i> H₃₇Rv with MIC values of 0.39 and 3.12 μg/mL, respectively

Sequential Pd(0)/Fe(III) Catalyzed Azide–Isocyanide Coupling/Cyclization Reaction: One-Pot Synthesis of Aminotetrazoles

A rapid and efficient synthesis of aminotetrazole from aryl azides, isocyanides, and TMSN₃ is developed. The reaction is promoted by sequential Pd(0)/Fe­(III) catalysis. The reaction sequence utilizes the Pd-catalyzed azide–isocyanide denitrogenative coupling reaction to generate unsymmetric carbodiimide <i>in situ</i>, which reacts with TMSN₃ in the presence of FeCl₃ in a single pot. The methodology has distinct advantages over traditional synthetic approaches where toxic Hg and Pb salts are employed at stoichiometric scale

<i>In</i><i>vivo</i> efficacy of

<p>HM. BALB/c mice were fed with HM (0.25 or 0.5 mg/kg) or ACV (5 mg/kg) and after 8 h of drug treatment the animals were infected with HSV-2G (9 X 10⁵ pfu per animal) intravaginally. The challenged animals of test groups were fed with HM twice daily for 7 days. Development of lesions and death were observed three times daily, while brain and vaginal tissue were collected after sacrification on days 2, 4, 6 or 8 after infection, homogenized and centrifuged. The supernatant was used for the determination of virus yield by plaque assay. Mean lesion score [A], Mean±S.D. of virus yield at log₁₀ (PFU/organ) in vaginal tissue [B] and brain [C]. </p

Anti-HSV efficacy of HM.

<p>[A] <b>Plaque </b><b>Reduction </b><b>Assay</b>. Infected cells were treated with HM or ACV at 0.5-50 μg/ml, overlaid with methylcellulose and plaques developed after 2-3 days were stained. The % of plaque number reduction was calculated, and the effective concentration of drug that inhibited the number of viral plaques was interpolated from the dose-response curve. [B] <b>Time </b><b>course </b><b>analysis</b>. Inhibitory effects of HM and ACV at various time points prior to infection (-3 to -1 h), at the time of infection (0 h) and post-infection (2-24 h) with HSV-2 were evaluated by plaque reduction assay. Each bar represents the mean ± S.E.M of three independent experiments.</p

Histopathology of Genital tissue of Balb/C mice

<p>: uninfected [A], infected with HSV-2G [B], HSV-2G infected animals treated with 0.5 µg/ml of HM [C], and ACV at 5 µg/ml [D]. </p

Effect of HM on viral IE transcriptional events.

<p>[A] <b>EMSA</b>: HSV-2G infected Vero cells were treated with HM for 2 and 4 h and assayed for EMSA. Biotin-labelled oligo was present in Lanes 1-6; P, biotin labelled oligo, M, mock control. [B] <b>Supershift </b><b>assay</b>: nuclear extracts from HSV-2G infected HM treated cells for 4 h p.i. was pre-incubated with HCF-1 polyclonal antibodies, added with reaction mixture, applied to non-denaturing 4% polyacrylamide gels and visualized by autoradiography. P, free biotin labelled probe; ns, nonspecific binding. [C] HCF-1 or LSD1 were immunoprecipitated in HM treated virus infected Vero cell lysate and the association was confirmed by immunoblotting with anti-HCF-1 and anti-LSD1 antibodies. </p