Synthesis and biological evaluation of Ribo 7-N/O/S pyrimidine 9-deaza C-nucleoside analogs as new antiviral agents for inhibiting HCV RNA-dependent RNA polymerases.

Hepatitis C infection is caused by the bloodborne pathogen hepatitis C virus (HCV) and can lead to serious liver diseases and, ultimately, death if the treatment is ineffective. This work reports the synthesis and preclinical evaluation of 7 novel 9-O/N/S pyrimidine nucleosides, including compound 12, the triphosphate of known compound 7b. The nucleosides are 9-deaza modifications of adenosine and guanosine with ß-2'-C-methyl substituent on the ribose. Within this series of compounds, a 9-deaza furopyrimidine analog of adenosine, compound 7b, showed high anti-HCV activity in vitro, good stability, low toxicity, and low genotoxicity when administrated in low doses, and an adequate pharmacokinetics profile. An improved synthesis of compound 7b compared to a previous study is also reported. Compound 12 was synthesized as a control to verify phosphorylation of 7b occurred in vivo.

Synthesis of novel azasugar-containing 2'ß-C-Me 9-deaza nucleosides as potential anti-hepatitis C virus agents.

As a part of our ongoing discovery efforts exploring azasugar as agents for treating various unmet medical needs, we prepared analogs of azasugar as potential anti-hepatitis C virus (HCV) agents. Herein we describe the synthesis of novel 2'ß-C-Me 9-deazanucleoside azasugar analogs.

Discovery and optimization of orally bioavailable and potent plasma Kallikrein inhibitors bearing a quaternary carbon.

Hereditary angioedema (HAE) is a rare and potentially life-threatening disease that affects an estimated 1 in 50,000 individuals worldwide. Berotralstat (BCX7353) is the only small molecule approved by the US Food and Drug Administration (FDA) for the prophylactic treatment of HAE attacks in patients 12 years and older. During the discovery of BCX7353, we also identified a novel series of small molecules containing a quaternary carbon as potent and orally bioavailable Plasma Kallikrein (PKal) inhibitors. Lead compound was identified as a potent inhibitor following a detailed lead optimization process that balanced the lipophilic efficiency (LipE) and pharmacokinetic (PK) profile.

Scaffold hopping via ring opening enables identification of acyclic compounds as new complement Factor D inhibitors.

The three complement pathways comprising the early phase of the complement system (the classical, lectin, and alternative pathways) act together with the innate and adaptive immune systems to protect against foreign entities and maintain tissue homeostasis. While these systems are normally under tight regulatory control, several diseases have been reported to correlate with uncontrolled activation and amplification of the alternative pathway, including paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, C3 glomerulopathy, and age-related macular degeneration. Complement FactorD (CFD), a serine protease, is the rate-limiting enzyme for the activity of alternative pathway. CFD activates the alternative pathway by cleaving Complement Factor B complexed to C3b (C3bB) to generate alternative pathway C3 convertase (C3bBb). In our search for novel CFD inhibitors with therapeutic potential, we employed a hot-spot analysis of an ensemble of apo and holo CFD structures. This analysis identified potential pharmacophore features that aided in the design of a series of compounds based on an l-proline core. While these compounds inhibited CFD in an esterolytic assay (for example, a proline-based compound, IC50 = 161 nM), the pharmacokinetic (PK) properties were poor. A strategy of scaffold hopping via ring opening led to a novel series of acyclic compounds, with subsequent structure-based ligand design and lead optimization producing several novel CFD inhibitors. One of these inhibitors, 1-(2-((2-(3-chloro-2-fluorobenzylamino)-2-oxoethyl)(cyclopropyl)amino)-2-oxoethyl)-5-(3-methyl-3-(1-methylpiperidin-4-yl)ureido)-1H-indazole-3-carboxamide, showed good potency with IC50s of 37 nM in the esterolytic assay and 30 nM in a hemolytic assay and PK assessments following oral administration to rats revealed a Cmax of 113 ng/mL and an AUC0-24h of 257 hr.ng/mL.

Berotralstat (BCX7353): Structure-Guided Design of a Potent, Selective, and Oral Plasma Kallikrein Inhibitor to Prevent Attacks of Hereditary Angioedema (HAE).

Hereditary angioedema (HAE) is a rare and potentially life-threatening disease that affects an estimated 1 in 50 000 individuals worldwide. Until recently, prophylactic HAE treatment options were limited to injectables, a burdensome administration route that has driven the need for an oral treatment. A substantial body of evidence has shown that potent and selective plasma kallikrein inhibitors that block the generation of bradykinin represent a promising approach for the treatment of HAE. Berotralstat (BCX7353, discovered by BioCryst Pharmaceuticals using a structure-guided drug design strategy) is a synthetic plasma kallikrein inhibitor that is potent and highly selective over other structurally related serine proteases. This once-daily, small-molecule drug is the first orally bioavailable prophylactic treatment for HAE attacks, having successfully completed a Phase III clinical trial (meeting its primary end point) and recently receiving the U.S. Food and Drug Administration's approval for the prophylactic treatment of HAE attacks in patients 12 years and older.

An efficient synthesis of acyclic N7- and N9-adenine nucleosides via alkylation with secondary carbon electrophiles to introduce versatile functional groups at the C-1 position of acyclic moiety.

The introduction of versatile functional groups, allyl and ester, at the C-1 position of the acyclic chain in acyclic adenine nucleosides was achieved for the first time directly by alkylation of adenine and N6-potected adenine. Thus, the C-1'-substituted N9-adenine acyclic nucleoside, adenine-9-yl-pent-4-enoic acid ethyl ester (11), was prepared by direct alkylation of adenine with 2-bromopent-4-enoic acid ethyl ester (6), while the corresponding N7-regioisomer, 2-[6-(dimethylaminomethyleneamino)-purin-7-yl]-pent-4-enoic acid ethyl ester (10), was obtained in one step by the coupling of N, N-dimethyl-N'- (9H-purin-6-yl)-formamidine (9) with 2-bromopent-4-enoic acid ethyl ester (6). The functional groups, ester and allyl, were converted to the desired hydroxymethyl and hydroxyethyl groups, and subsequently to phosphonomethyl derivatives and corresponding pyrophosphorylphosphonates.

Synthesis of 9-[1-(substituted)-3-(phosphonomethoxy)propyl]adenine derivatives as possible antiviral agents.

Acyclic N9 adenine nucleosides substituted at C-1' position were prepared by the Mitsunobu reaction of 1-tert-butyldimethylsilyl-4-pivaloylbutan-1,2,4-triol (5) with adenine. Pivaloyl hydroxyl was modified to the phosphonomethoxy derivatives, and the tert-butyldimethylsilyl hydroxyl was converted to methoxy, azido, amino, fluoro, and c-hydroxyethyl and was eliminated to give vinyl. The resulting phosphonic acids were converted to prodrugs also.

Synthesis of 9-[1-(substituted)-2-(phosphonomethoxy)ethyl]adenine derivatives as possible antiviral agents.

Various C-1'-substituted acyclic N9 adenine nucleosides were prepared from 9-[(1-hydroxymethyl)(3-monomethoxytrityloxy)propyl]-N6-monomethoxytrityladenine. The hydroxymethyl was modified to the phosphonomethoxy derivative, and the 3-monomethoxytrityloxy was converted to hydroxyl, methoxy, azido, and amino. Other substituents, such as ethyl and ea-hydroxyethyl were also prepared. The resulting phosphonomethoxy derivatives were converted to prodrugs.

Synthesis of 9-[1-(1 -hydroxyethyl)-3-(phosphonomethoxy)propyl]adenine and prodrug as possible antiviral agents.

The appropriately protected C-1'-hydroxyethyl-3-hydroxypropyl-N9-adenine nucleoside was prepared from 1-pivaloyloxy-5-tert-butyldiphenylsilyloxy-3-pentanol and adenine through the Mitsunobu reaction. One of the terminal hydroxyls was converted to the phosphonomethoxy derivative and the prodrug.

Synthesis of N6-substituted 9-[3-(phosphonomethoxy)propyl]adenine derivatives as possible antiviral agents.

A number of N6-substituted 9-[3-(phosphonomethoxy)propyl]adenine derivatives having hydroxymethyl at C-1' position were prepared from the appropriate 6-chloroadenine derivative. The syntheses of the corresponding prodrugs of these compounds are also reported. These compounds showed poor activity against HCV in replicon assay.