Synthesis and anti-HCMV activity of 1-acyl-beta-lactams and 1-acylazetidines derived from phenylalanine

Synthesis and antimicrobial activities of some novel diastereoselective monocyclic cis-β-lactams using 2-ethoxy carbonyl DCPN as a carboxylic acid activator

A series of novel monocyclic cis-β-lactams were prepared from phenoxyacetic acid as ketene source and imines derived from 1-chloro-3,4-dihydronaphthalene-2-carbaldehyde and respective amine using ethyl 4,5-dichloro-6-oxopyridazine-1(6H)-carboxylate (or 2-ethoxy carbonyl DCPN) as a carboxylic acid activator. This is the first time 2-ethoxy carbonyl DCPN has been used as an acid activator in synthesis of β-lactams. The reaction was entirely diastereoselective leading to the formation cis-β-lactam derivatives. These newly synthesized cis-β-lactam were fully characterized by FT-IR, 1H NMR, 13C NMR, HRMS, CHNS and X-ray crystallography study. All this novel compound was also evaluated for their antibacterial and antifungal activities against certain strains of Gram-positive bacteria, Gram-negative bacteria and fungi. These compounds displayed moderate activity against using bacterial and fungal strains.

Novel N-Substituted 3-Aryl-4-(diethoxyphosphoryl)azetidin-2-ones as Antibiotic Enhancers and Antiviral Agents in Search for a Successful Treatment of Complex Infections

A novel series of N-substituted cis- and trans-3-aryl-4-(diethoxyphosphoryl)azetidin-2-ones were synthesized by the Kinugasa reaction of N-methyl- or N-benzyl-(diethyoxyphosphoryl)nitrone and selected aryl alkynes. Stereochemistry of diastereoisomeric adducts was established based on vicinal H3-H4 coupling constants in azetidin-2-one ring. All the obtained azetidin-2-ones were evaluated for the antiviral activity against a broad range of DNA and RNA viruses. Azetidin-2-one trans-11f showed moderate inhibitory activity against human coronavirus (229E) with EC50 = 45 µM. The other isomer cis-11f was active against influenza A virus H1N1 subtype (EC50 = 12 µM by visual CPE score; EC50 = 8.3 µM by TMS score; MCC > 100 µM, CC50 = 39.9 µM). Several azetidin-2-ones 10 and 11 were tested for their cytostatic activity toward nine cancerous cell lines and several of them appeared slightly active for Capan-1, Hap1 and HCT-116 cells values of IC50 in the range 14.5-97.9 µM. Compound trans-11f was identified as adjuvant of oxacillin with significant ability to enhance the efficacy of this antibiotic toward the highly resistant S. aureus strain HEMSA 5. Docking and molecular dynamics simulations showed that enantiomer (3R,4S)-11f can be responsible for the promising activity due to the potency in displacing oxacillin at β-lactamase, thus protecting the antibiotic from undesirable biotransformation.

Monocyclic β-Lactam: A Review on Synthesis and Potential Biological Activities of a Multitarget Core

A monocyclic ring in their structure characterizes monobactams, a subclass of β-lactam antibiotics. Many of these compounds have a bactericidal mechanism of action and acts as penicillin and cephalosporins, interfering with bacterial cell wall biosynthesis. The synthesis of novel β-lactams is an emerging area of organic synthesis research due to the problem of increasing bacterial resistance to existing β -lactam antibiotics, and, in this way, new compounds have been presented with several structural modifications, aiming to improve biological activities. Among the biological activities studied, the most outstanding are antibacterial, antitubercular, anticholesterolemic, anticancer, antiinflammatory, antiviral, and anti-enzymatic, among others. This review explores the vast number of works related to monocyclic β-lactams, compounds of great importance in scientific research.

Crystal structure of 1-(4-meth-oxy-phen-yl)-4-(4-nitro-phen-yl)-3-phen-oxy-azetidin-2-one

In the title compound, C22H18N2O5, the central β-lactam ring (r.m.s. deviation = 0.002 Å) makes dihedral angles of 64.21 (14), 82.35 (12) and 20.66 (13)° with the phenyl ring and the nitro- and meth-oxy-benzene rings, respectively. The mol-ecular structure is stabilized by an intra-molecular C-H⋯O hydrogen bond. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, forming slabs lying parallel to (111). The slabs are linked via C-H⋯π inter-actions, forming a three-dimensional network.

Anti-herpesvirus agents: a patent and literature review (2003 to present)

INTRODUCTION

The standard therapy used to treat herpesvirus infections is based on the application of DNA polymerase inhibitors such as ganciclovir or aciclovir. Unfortunately, all of these compounds exhibit relatively high toxicity and the mutation of herpesviruses results in the appearance of new drug-resistant strains. Consequently, there is a great need for the development of new, effective and safe anti-herpesvirus agents that employ different patterns of therapeutic action at various stages of the virus life cycle.

AREAS COVERED

Patents and patent applications concerning the development of anti-herpesvirus agents displaying different mechanisms of action that have been published since 2003 are reviewed. In addition, major discoveries in this field that have been published in academic papers have also been included.

EXPERT OPINION

Among all the anti-herpesvirus agents described in this article, the inhibitors of viral serine protease seem to present one of the most effective/promising therapeutics. Unfortunately, the practical application of these antiviral agents has not yet been proven in any clinical trials. Nevertheless, the dynamic and extensive work on this subject gives hope that a new class of anti-herpesvirus agents aimed at the enzymatic activity of herpesvirus serine protease may be developed.

The chemistry and biological potential of azetidin-2-ones

Azetidin-2-ones, commonly referred as β-lactams, represent a unique ring system, with interesting chemistry and great biological potential. Besides its well known antibiotic activity, this ring system exhibits a wide range of activities, attracting the attention of researchers. The biological and pharmacological profile of azetidin-2-ones is reviewed here comprehensively with several examples under fourteen different activity heads. The chemistry and methods of synthesis have also been discussed.

(S)-1-(Pent-4'-enoyl)-4-(hydroxymethyl)-azetidin-2-one derivatives as inhibitors of human fatty acid amide hydrolase (hFAAH): synthesis, biological evaluation and molecular modelling

A series of lipophilic ester derivatives (2a-g) of (S)-1-(pent-4'-enoyl)-4-(hydroxymethyl)-azetidin-2-one has been synthesised in three steps from (S)-4-(benzyloxycarbonyl)-azetidin-2-one and evaluated as novel, reversible, β-lactamic inhibitors of endocannabinoid-degrading enzymes (human fatty acid amide hydrolase (hFAAH) and monoacylglycerol lipase (hMAGL)). The compounds showed IC50 values in the micromolar range and selectivity for hFAAH versus hMAGL. The unexpected 1000-fold decrease in activity of 2a comparatively to the known regioisomeric structure 1a (i.e. lipophilic chains placed on N1 and C3 positions of the β-lactam core) could be explained on the basis of docking studies into a revisited model of hFAAH active site, considering one or two water molecules in interaction with the catalytic triad.

Recent developments in antiviral drugs for cytomegalovirus

Human cytomegalovirus continues to impact adversely on the outcome of solid organ and stem cell transplantation and remains a major cause of congenital abnormalities. In the absence of a vaccine, antiviral drugs have been the mainstay of therapy. Although very few anticytomegalovirus drugs are currently licensed, there are multiple opportunities within the viral life cycle for drug development. In this article we summarize some of the key new antiviral agents undergoing preclinical and clinical development against a range of targets in the viral life cycle, highlighting those where further development is warranted or being undertaken.

Synthesis and SAR studies on azetidine-containing dipeptides as HCMV inhibitors

SAR studies on an azetidine-containing dipeptide prototype inhibitor of HCMV are described. Three series of structurally modified analogues, involving substitutions at the N- and C-terminus, and at the C-terminal side-chain were synthesized and evaluated for antiviral activity. Aliphatic or no substituents at the C-carboxamide group, an aliphatic C-terminal side-chain, as well as a benzyloxycarbonyl moiety at the N-terminus were absolute requirements for anti-HCMV activity. The conformational restriction induced by the 2-azetidine residue into the dipeptide derivatives, identified by ¹H NMR as a γ-type reverse turn, seems to have influence on the activity of these molecules.

Green route for the heterocyclization of 2-mercaptobenzimidazole into β-lactum segment derivatives containing –CONH– bridge with benzimidazole: Screening in vitro antimicrobial activity with various microorganisms

The efficient and rapid synthesis of novel azetidin-2-ones 4a-j has been established. Thus, both microwave and conventional condensation 2-{(1H-benzimidazol)-ylthio}-N'-2-(substituted phenyl) hydrazide with chloroacetylchloride were carried out in DMF-benzene solvent in the presence of Et(3)N catalyst. The microwave synthesis route afforded better yield with short time. The novel heterocycles were characterized by elemental analysis and spectral features. Some of the produced compounds were screened for their antimicrobial activity.

Novel yeast cell-based assay to screen for inhibitors of human cytomegalovirus protease in a high-throughput format

The protease encoded by the human cytomegalovirus (HCMV) is an attractive target for antiviral drug development because of its essential function in viral replication. We describe here a cellular assay in the yeast Saccharomyces cerevisiae for the identification of small molecule inhibitors of HCMV protease by conditional growth in selective medium. In this system, the protease cleavage sequence is inserted into the N-(5'-phosphoribosyl)anthranilate isomerase (Trp1p), a yeast protein essential for cell proliferation in the absence of tryptophan. Coexpression of HCMV protease with the engineered Trp1p substrate in yeast cells results in site-specific cleavage and functional inactivation of the Trp1p enzyme, thereby leading to an arrest of cell proliferation. This growth arrest can be suppressed by the addition of validated HCMV protease inhibitors. The growth selection system presented here provides the basis for a high-throughput screen to identify HCMV protease inhibitors that are active in eukaryotic cells.

Synthesis of novel N-sulfonyl monocyclic beta-lactams as potential antibacterial agents

New cis monocyclic beta-lactams were synthesized by [2+2] Staudinger cycloaddition reactions of the imine (3,4-dimethoxybenzylidene)-(4-methoxyphenyl)-amine and ketenes derived from different acyl chlorides and Et3N. These monocyclic beta-lactams were then cleaved by ceric ammonium nitrate (CAN) to give NH-monocyclic beta-lactams, which in turn were converted to N-sulfonyl monocyclic beta-lactams by treatment with four different sulfonyl chlorides in the presence of Et3N and 4,4-dimethyl-aminopyridine (DMAP).

Beta-lactam compounds as apparently uncompetitive inhibitors of HIV-1 protease

Compounds of a combinatorial monocyclic beta-lactam library were found to be apparently uncompetitive inhibitors of HIV-1 protease, providing lead compounds for a new class of HIV protease inhibitors.

From 1-acyl-beta-lactam human cytomegalovirus protease inhibitors to 1-benzyloxycarbonylazetidines with improved antiviral activity. A straightforward approach to convert covalent to noncovalent inhibitors

Starting from the structure of known beta-lactam covalent human cytomegalovirus (HCMV) protease inhibitors and from the knowledge of the residues implicated in the active site of this enzyme, we designed a series of phenylalanine-derived 2-azetidinones bearing a 4-carboxylate moiety that could be apt for additional interactions with the guanidine group of the Arg165/Arg166 residues of the viral protease. Some compounds within this series showed anti-HCMV activity at 10-50 muM, but rather high toxicity. The presence of aromatic 1-acyl groups and a certain hydrophobic character in the region of the 4-carboxylate were stringent requirements for anti-HCMV activity. To go a step ahead into the search for effective HCMV medicines, we then envisaged a series of noncovalent inhibitors by simple deletion of the carbonyl group in the beta-lactam derivatives to provide the corresponding azetidines. This led to low micromolar inhibitors of HCMV replication, with 17 and 27 being particularly promising lead compounds for further investigation, although their toxicity still needs to be lowered.