Diastereoselective synthesis of potent antimalarial cis-β-lactam agents through a [2 + 2] cycloaddition of chiral imines with a chiral ketene

Novel (±)-trans-β-lactam ureas: Synthesis, in silico and in vitro biological profiling

A diastereomeric mixture of racemic 3-phthalimido-b-lactam 2a/2b was synthesized by the Staudinger reaction of carboxylic acid activated with 2-chloro-1-methylpyridinium iodide and imine 1. The amino group at the C3 position of the b-lactam ring was used for further structural upgrade. trans-b-lactam ureas 4a-t were prepared by the condensation reaction of the amino group of b-lactam ring with various aromatic and aliphatic isocyanates. Antimicrobial activity of compounds 4a-t was evaluated in vitro and neither antibacterial nor antifungal activity were observed. Several of the newly synthesized trans-b-lactam ureas 4a-c, 4f, 4h, 4n, 4o, 4p, and 4s were evaluated for in vitro antiproliferative activity against liver hepatocellular carcinoma (HepG2), ovarian carcinoma (A2780), breast adenocarcinoma (MCF7) and untransformed human fibroblasts (HFF1). The b-lactam urea 4o showed the most potent antiproliferative activity against the ovarian carcinoma (A2780) cell line. Compounds 4o and 4p exhibited strong cytotoxic effects against human non-tumor cell line HFF1. The b-lactam ureas 4a-t were estimated to be soluble and membrane permeable, moderately lipophilic molecules (logP 4.6) with a predisposition to be CYP3A4 and P-glycoprotein substrates. The tools PASS and SwissTargetPrediction could not predict biological targets for compounds 4a-t with high probability, pointing to the novelty of their structure. Considering low toxicity risk, molecules 4a and 4f can be selected as the most promising candidates for further structure modifications.

Anticancer activity and evaluation of apoptotic genes expression of 2-azetidinones containing anthraquinone moiety

Nowadays, one of the principal causes of death in the world is cancer. A series of 2-azetidinones containing anthraquinone moiety with various substituents were synthesized using [2 + 2] ketene-imine cycloaddition (Staudinger ketene-imine cycloaddition), and their cytotoxicity against some human cancer and normal cell lines was evaluated. Some of these hybrid compounds showed moderate to significant cytotoxicity against breast carcinoma (MCF7), colon carcinoma (HCT116), prostate carcinoma (PC3), and neuroblastoma (SKNMC) cell lines via MTT assay. Surprisingly, hybrid 4gh with the best anticancer activity demonstrated very good antibacterial and antifungal activities. This compound was selected to study to test on human fibroblast (Hu02) normal cell and comparison with doxorubicin. While 2-azetidinone 4gh represented similar cytotoxicity against cancer cell lines compared to doxorubicin, the 2-azetidinone demonstrated lower cytotoxicity against human fibroblast (Hu02) than doxorubicin. Further real-time PCR investigation displayed the expression of Bcl-xl, KI-67, TPX2 and BAX genes were significantly increased or decreased as desired in the cancer cell lines studied by treatment with doxorubicin or 2-azetidinone-anthraquinone 4gh. Molecular docking studies represented that hybrid 4gh strongly fitted the active site of topoisomerase II (PDB 4G0V) with hydrogen bond and hydrophobic interactions.

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.

Exploring multi-target inhibitors using in silico approach targeting cell cycle dysregulator-CDK proteins

Cyclin-dependent kinases (CDKs) belong to a family of multifunctional enzymes that control cell cycle modifications, transcription, and cell proliferation. Their dysfunctions result in different diseases like cancer making them an important drug target in oncology and beyond. The present study aims at identifying the selective inhibitors for ATP binding site in CDK proteins (CDK1, CDK2, CDK4, and CDK5) following a multi-target drug designing approach. Significant challenges lie in identifying the selective inhibitor for the ATP binding site as this region is highly conserved in all protein kinases. Molecular docking coupled with molecular dynamics simulation and free energy of binding calculations (MMPBSA/MMGBSA) were used to identify the potent competitive ATP binding site inhibitors. All the four proteins were docked against the library of drug-like compounds and the outcomes of the docking study were further analyzed by Molecular dynamics (total of 6μs) and MMPB/GBSA techniques. Five different inhibitors for structurally distant protein kinases, i.e. CDK1, CDK2, CDK4, and CDK5 are identified with the binding energy (ΔG_bind-PB) in the range -18.24 to -28.43Kcal/mol. Mechanistic complexities associated with the binding of the inhibitor are unraveled by carefully analyzing the MD trajectories. It is observed that certain residues (Lys33, Asp127, Asp145, Tyr15, Gly16, Asn144) and regions are critical for the retention of inhibitors in active pocket, and significant conformational changes take place in the active site region as well as its neighbor following the entry of the ligand inside active pocket as inferred by RMSD and RMSF. It is observed that LIG3 and LIG4 are the best possible inhibitors as reflected from their high binding energy, interaction pattern, and their retention inside the active pocket. This study will facilitate the process of multi-target drug designing against CDK proteins and can be used in the development of potential therapeutics against different diseases.

The facile and efficient synthesis of novel monocyclic cis-β-lactam conjugates with a 1-methyl-1H-imidazole-2-thiol nucleus

We developed a facile and efficient synthesis of novel monocyclic cis-β-lactam conjugates with a 1-methyl-1H-imidazole-2-thiol nucleus through a ketene-imine [2+2] cycloaddition reaction of acyl chloride and different Schiff bases.

Synthesis and In Vitro Antiprotozoan Evaluation of 4-/8-Aminoquinoline-based Lactams and Tetrazoles

A second generation of 4-aminoquinoline- and 8-aminoquinoline-based tetrazoles and lactams were synthesized via the Staudinger and Ugi multicomponent reactions. These compounds were subsequently evaluated in vitro for their potential antiplasmodium activity against a multidrug-resistant K1 strain and for their antitrypanosomal activity against a cultured T. b. rhodesiense STIB900 strain. Several of these compounds (4a-g) displayed good antiplasmodium activities (IC50 = 0.20-0.62 µM) that were comparable to the reference drugs, while their antitrypanosomal activity was moderate (<20 µM). Compound 4e was 2-fold more active than primaquine and was also the most active (IC50 = 7.01 µM) against T. b. rhodesiense and also exhibited excellent aqueous solubility (>200 µM) at pH 7.

Targeting protein tyrosine phosphatase to unravel possible inhibitors for Streptococcus pneumoniae using molecular docking, molecular dynamics simulations coupled with free energy calculations

AIMS

Protein tyrosine phosphatase (PTP-CPS4B) is a signaling enzyme that is essential for a wide range of cellular processes, like metabolism, proliferation, survival and motility. Studies suggest that PTPs are vital for the production of Wzy-dependent capsule in bacteria, making it a valuable target for the discovery of pneumonia associated anti-virulence antibacterial agents. Present study aims at identifying the potential drug candidates to be exploited in inhibiting the growth of Streptococcus pneumonia targeting PTP-CPS4B.

MATERIALS AND METHODS

The present study exploits the molecular docking potential coupled with molecular dynamic simulation as well as free energy calculations to identify potential inhibitors of PTP-CPS4B. Libraries of known and unknown compounds were docked into the active site of PTP-CPS4B using MOE. The compounds with best binding affinity and orientation were subjected to MD simulations and free energy calculations.

FINDINGS

Top three compounds based on their binding energy and well composed interaction pattern obtained from molecular docking study were subjected to MD simulations and were compared to reported antibiotic drugs. MD Simulation studies have shown that the presence of an inhibitor inside the active site reduces protein flexibility as evident from RMSD, RMSF and Principal component analyses. MD simulations identified a transition from extended to bended motional shift in loop α6 of the PTP-CPS4B in ligand bound state. This flexibility was reported in the RMSF analysis and verified by the visual investigation of the loop α6 at different time intervals during the simulation. Free energy of binding affinity (computed using MMPBSA &MMGBSA approach) and the interaction patterns obtained from MD trajectory indicate that compound ZN1 (-31.50 Kcal/mol), ZN2 (-33.14 Kcal/mol) and ZN3 (-26.60 Kcal/mol) are potential drug candidates against PTP-CPS4B. Residue wise decomposition study helped in identifying the role of individual amino acid towards the overall inhibition behavior of the compounds. PCA analysis has led to the conclusion that the behavior of PTP-CPS4B inhibitors causes conformational dynamics that can be used to describe the protein inhibition mechanism.

SIGNIFICANCE

The outcome reveals that this study provide enough evidences for the consideration of ZN1, ZN2, ZN3 as potential PTP-CPS4B inhibitors and further in vitro and in vivo studies may prove their therapeutic potential.

Synthesis, in vitro biological evaluation and in silico molecular docking studies of novel β-lactam-anthraquinone hybrids

Schiff bases from 2-aminoanthraquinone have been prepared by reaction with aldehydes and used to prepare novel β-lactam-anthraquinone hybrids via [2+2] ketene-imine cycloaddition (Staudinger reaction) reaction. In vitro antibacterial studies of all synthesized compound were carried out against three gram-positive strains Staphylococcus aureus (Methicillin-resistant strain), Enterococcus faecium (Vancomycin-resistant strain) and Bacillus subtilis, and two gram-negative strains Escherichia coli and Pseudomonas aeruginosa. These compounds were further evaluated for their in vitro antifungal activity against Candida albicans, Aspergillus niger and Trichophyton mentagrophytes. Hybrid compounds showed moderate to excellent antibacterial and antifungal activities. Surprisingly, among the tested compounds, some of them revealed equal antibacterial and antifungal properties and even better than standards. In addition, results demonstrated that the new hybrids are very promising antibacterial agents against resistant strains. Also molecular docking studies were carried out by Autodoc software. Penicillin-binding protein 2a (PDB ID: 1VQQ) from methicillin-resistant Staphylococcus aureus strain used as a target which good binding interactions were observed.

Recent advances in β-lactam synthesis

During the past century, β-lactams have been identified as the core of penicillin and since then several strategies have been developed for their synthesis.