Synthesis and Antibacterial evaluation of Rhodanine and Its related heterocyclic compounds against S. aureus and A. baumannii

Antimicrobial resistance is a serious challenge to modern medicine. Besides imposing high financial burden, multidrug resistant infections are directly responsible for high morbidity and mortality. Even though a number of antibiotics are currently available to treat infections caused by ESKAPE organisms, more and more bacterial strains are becoming resistant to these drugs. In these circumstances, there is an urgent unmet need for development of newer antimicrobials to treat the infections caused due to MDR organisms. Rhodanine and structurally related 5-membered heterocycles possess wide range of pharmacological activities. A number of these derivatives have shown good to potent inhibition against the various microorganisms. They are reported to alter the functions of DNA gyrase B, metallo-β-lactamases, pencilline binding protein (PBP), Mur ligases, RNA polymerase, Enoyl ACP reductases, 1-deoxy-d-xylulose-5-phosphate reductoisomerase. etc which are vital molecular targets involved in bacterial growth, survival and replication. In this study, we have generated a library of Rhodanine and related 5 membered heterocyclic derivatives and screened them against a panel of pathogens. Among all the compounds, 2a-i, 3a-b, 3g, 4, 6b-c, 6e, 6g, 12a-b and 14b-c have demonstrated good to moderate inhibition against S. aureus (MIC 0.125-8 µ g/mL). Further, compound 17b demonstrated moderate activity against A. baumannii (MIC 8 µ g/mL). In addition, compounds 2a, 2e, 4, 6c, 6g and 14b have shown good to mild inhibition against MDR S. aureus including VRSA (MIC 0.5-16 µ g/mL) with good selectivity index 20-1600. In addition, compound 2e has inhibited growth gradually after 6 h in time kill kinetic studies and not antagonized with the tested FDA approved drugs.

DFT calculation, molecular docking, and molecular dynamics simulation study on substituted phenylacetamide and benzohydrazide derivatives

The atomic and molecular properties of the title compounds were calculated by Jaguar using a basis set B3LYP/6-31G**⁺⁺ with hybrid DFT in the gas phase, to determine the chemical reactivity. Analysis of quantum chemical features such as HOMO and LUMO explained that the electronic charge transfer occurred within the system through conjugated paths of the selected compounds. The nucleophilic and electrophilic reactive sites are recognized from the molecular electrostatic potential plot. Electrophilic and nucleophilic attack-prone molecular sites were predicted by mapping ALIE value to the molecular surface. The bond dissociation energy of the high active compound 15 (2-chloro-N-(2-(2-(2-(2-chlorobenzoyl)hydrazineyl)-2-oxoethoxy)phenyl)acetamide) was calculated to assess the probability of compound autoxidation or degradation. Further, molecular docking, binding free energy calculations, and ADMET profile of the degradation products (DPs) of compound 15 was carried out to determine the binding affinity and toxicity profile of the formed DPs compared with the parent compound. A 150-ns molecular dynamics (MD) simulation was performed to evaluate the binding stability of the compound 15/4URL complex using Desmond. Binding free energy and binding affinity of the complex were computed for 100 trajectory frames using the MM-GBSA approach.

Synthesis, Molecular Docking and Biological Evaluation of 2-Aryloxy-N-Phenylacetamide and N'-(2-Aryloxyoxyacetyl) Benzohydrazide Derivatives as Potential Antibacterial Agents

A new class of 2-aryloxy-N-phenylacetamide and N'-(2-aryloxyoxyacetyl) benzohydrazide derivatives with different active moieties were synthesized and screened for their antibacterial activity. Structural characterization of synthesized compounds was performed using HR-MS, ¹ H-NMR, and ¹³ C-NMR spectral data. Amongst the synthesized compounds, 4-{2-[2-(2-chloroacetamido)phenoxy]acetamido}-3-nitrobenzoic acid (3h) and 2-chloro-N-(2-{2-[2-(2-chlorobenzoyl)hydrazinyl]-2-oxoethoxy}phenyl)acetamide (3o) have shown good antibacterial activity against a selected panel of bacteria. Besides, compounds also exhibited bactericidal activity against P. aeruginosa (3h, 0.69 μg/mL) and S. aureus (3o, 0.62 μg/mL) as evident by MBC and time-kill kinetics studies. In silico molecular docking and ADMET properties of newly synthesized compounds revealed that compounds could be considered as promising antibacterial agents.

Development of Simplified Heterocyclic Acetogenin Analogues as Potent and Selective Trypanosoma brucei Inhibitors

Neglected tropical diseases caused by parasitic infections are an ongoing and increasing concern. They are a burden to human and animal health, having the most devastating effect on the world's poorest countries. Building upon our previously reported triazole analogues, in this study we describe the synthesis and biological testing of other novel heterocyclic acetogenin-inspired derivatives, namely 3,5-isoxazoles, furoxans, and furazans. Several of these compounds maintain low-micromolar levels of inhibition against Trypanosoma brucei, whilst having no observable inhibitory effect on mammalian cells, leading to the possibility of novel lead compounds for selective treatment.

Benzofuroxan derivatives N-Br and N-I induce intrinsic apoptosis in melanoma cells by regulating AKT/BIM signaling and display anti metastatic activity in vivo

Background

Malignant melanoma is an aggressive type of skin cancer, and despite recent advances in treatment, the survival rate of the metastatic form remains low. Nifuroxazide analogues are drugs based on the substitution of the nitrofuran group by benzofuroxan, in view of the pharmacophore similarity of the nitro group, improving bioavailability, with higher intrinsic activity and less toxicity. Benzofuroxan activity involves the intracellular production of free-radical species. In the present work, we evaluated the antitumor effects of different benzofuroxan derivatives in a murine melanoma model.

Methods

B16F10-Nex2 melanoma cells were used to investigate the antitumor effects of Benzofuroxan derivatives in vitro and in a syngeneic melanoma model in C57Bl/6 mice. Cytotoxicity, morphological changes and reactive oxygen species (ROS) were assessed by a diphenyltetrasolium reagent, optical and fluorescence microscopy, respectively. Annexin-V binding and mitochondrial integrity were analyzed by flow cytometry. Western blotting and colorimetry identified cell signaling proteins.

Results

Benzofuroxan N-Br and N-I derivatives were active against murine and human tumor cell lines, exerting significant protection against metastatic melanoma in a syngeneic model. N-Br and N-I induce apoptosis in melanoma cells, evidenced by specific morphological changes, DNA condensation and degradation, and phosphatidylserine translocation in the plasma membrane. The intrinsic mitochondrial pathway in B16F10-Nex2 cells is suggested owing to reduced outer membrane potential in mitochondria, followed by caspase −9, −3 activation and cleavage of PARP. The cytotoxicity of N-Br and N-I in B16F10-Nex2 cells is mediated by the generation of ROS, inhibited by pre-incubation of the cells with N-acetylcysteine (NAC). The induction of ROS by N-Br and N-I resulted in the inhibition of AKT activation, an important molecule related to tumor cell survival, followed by upregulation of BIM.

Conclusion

We conclude that N-Br and N-I are promising agents aiming at cancer treatment. They may be useful in melanoma therapy as inducers of intrinsic apoptosis and by exerting significant antitumor activity against metastatic melanoma, as presently shown in syngeneic mice.

Ligand-based design, synthesis, and experimental evaluation of novel benzofuroxan derivatives as anti-Trypanosoma cruzi agents

A set of substituted-[N'-(benzofuroxan-5-yl)methylene]benzohydrazides (4a-t), previously designed and synthesized, was experimentally assayed against Trypanosoma cruzi, the etiological agent of Chagas' disease, one of the most neglected tropical diseases. Exploratory data analysis, Hansch approach and VolSurf formalism were applied to aid the ligand-based design of novel anti-T. cruzi agents. The best 2D-QSAR model showed suitable statistical measures [n = 18; s = 0.11; F = 42.19; R(2) = 0.90 and Q(2) = 0.77 (SDEP = 0.15)], and according to the optimum 3D-QSAR model [R(2) = 0.98, Q(2) = 0.93 (SDEP = 0.08)], three latent variables explained 62% of the total variance from original data. Steric and hydrophobic properties were pointed out as the key for biological activity. Based upon the findings, six novel benzofuroxan derivatives (4u-z) were designed, synthesized, and in vitro assayed to perform the QSAR external prediction. Then, the predictability for the both models, 2D-QSAR (Rpred(2) = 0.91) and 3D-QSAR (Rpred(2) = 0.77), was experimentally validated, and compound 4u was identified as the most active anti-T. cruzi hit (IC50 = 3.04 μM).