Discovery of pyrazinone based compounds that potently inhibit the drug-resistant enzyme variant R155K of the hepatitis C virus NS3 protease

N-Acylsulfonamide: a valuable moiety to design new sulfa drug analogues

Sulfonamides are the oldest class of antibiotics, discovered more than 80 years ago. They are still used today despite the appearance of drug resistance phenomena that limit their prescription. Since the discovery and use of the first sulfa drugs, many analogues have been synthesized in order to obtain new active molecules able to circumvent bacterial resistance. Structurally similar to sulfonamide, the N-acylsulfonamide group arouses interest in the field of medicinal chemistry due to specific physico-chemical properties. We report here the synthesis and antibacterial/antibiofilm activities of 18 sulfa drug analogues with an N-acylsulfonamide moiety. These derivatives were obtained efficiently by sulfo-click reactions between readily available thioacid and sulfonyl azide synthons.

Four-Component Synthesis of Polysubstituted Pyrazin-2(1H)-ones through a Ugi/Staudinger/Aza-Wittig/Isomerization Sequence

A new efficient synthesis of polysubstituted pyrazin-2(1H)-ones via the sequential Ugi/Staudinger/aza-Wittig/isomerization reaction has been developed. The four-component Ugi reactions of arylglyoxals 1, primary amines 2, α-azidovinyl acids 3, and isocyanides 4 produced the azides 5, which were treated with triphenylphosphine to give pyrazin-2(1H)-ones 6 in good yields through domino Staudinger/aza-Wittig/isomerization reactions.

HCV genotype-1 subtypes and resistance-associated substitutions in drug-naive and in direct-acting antiviral treatment failure patients

BACKGROUND

Direct-acting antiviral (DAA) treatment regimens and response rates of patients with HCV genotype-1 (GT1) are currently considered subtype-dependent. Identification of clinically relevant resistance-associated substitutions (RASs) in the NS3 and NS5A proteins at baseline and in DAA failures, may also impact clinical decisions.

METHODS

In a multicentre cohort study (n=308), NS3 or NS5B sequencing (n=248) was used to discriminate between GT1 subtypes. The correlation between baseline NS3 and NS5A RASs on the 12-week sustained virological response (SVR12) rates of 160 of the patients treated with second-generation DAAs was also assessed. Post-treatment resistance analysis was performed on samples from 58 patients exhibiting DAA virological failure.

RESULTS

GT1a, GT1b and GT1d subtypes were identified in 23.0%, 75.4% and 1.2% of tested samples. GT1b was most prevalent (97.7%, 128/131) among patients born in the former Soviet Union. The Q80K NS3 RAS was identified in 17.5% (10/57) of the GT1a carriers, most of whom were Israeli-born. NS3 and NS5A baseline RASs showed a negligible correlation with SVR12 rates. Treatment-emergent RASs were observed among 8.9% (4/45) and 76.9% (10/13) of first- and second-generation DAA failures, respectively, with D168V/E (NS3), Y93H and L31M (NS5A) being the most prevalent mutations.

CONCLUSIONS

NS3 sequencing analysis can successfully discriminate between GT1 subtypes and identify NS3 amino acid substitutions. While pre-treatment NS3 and NS5A RASs marginally affect second-generation DAA SVR12 rates, post-treatment resistance analysis should be considered prior to re-therapy.