Synthesis and molecular descriptor characterization of novel 4-hydroxy-chromene-2-one derivatives as antimicrobial agents

Comparative study of experimental and DFT calculations for 3-cinnamoyl 4-hydroxycoumarin derivatives

BACKGROUND

Computational research plays an important role in predicting the chemical and physical properties of biologically active compounds important in future structural modifications to improve or modify biological activity.

OBJECTIVE

This research focuses on quantum chemical and spectroscopic investigations properties of synthesized 4-hydroxycoumarin derivatives.

METHODS

Quantum chemical calculations were obtained using B3LYP, HF, and M06-2x level methods with the 6-31++G (d,p) basis set. Afterward, IR, 1H, 13C, UV-Visible experimentally parameters were compared with the results obtained using the B3LYP/6-31+G*(d) basis set of the molecules to be able to characterize the structures.

RESULTS

Based on the quantum chemical calculations compound with acetamido group on the phenyl ring is the most reactive, and compound with nitro substituent is the least reactive and the the strongest electrophile among tested compounds. With the exception of compounds with dimethylamino group, all other compounds have a pronounced tautomer between OH and C = O group. The calculated and experimental values are in agreement with each other.

CONCLUSION

The molecular structure in the ground state of six 3-cinnamoyl 4-hydroxycoumarin derivatives was optimized using density functional theory. The observed and computed values were compared and it can be concluded that the theoretical results were in good linear agreement with the experimental data.

Structural tuning of β-enamino diketones: exploration of solution and crystalline state photochromism

A library of β-enamino diketones was prepared via base-mediated, three-component reaction of 4-hydroxycoumarins with various aromatic/aliphatic amines and β-nitrostyrenes under microwave irradiation conditions to investigate their photochemical properties. Among the prepared compounds, a thiophene derived β-enamino diketone was found to be light-sensitive and to exhibit unique photochromic behavior, that is, positive photochromism in solution and negative photochromism in crystalline phase. In addition, this prepared photochromic compound was further covalently linked to a structure-related, piezochromic β-enamino diketone moiety to explore its potential multi-stimuli responsive properties.

Intramolecular Diels-Alder Cycloaddition of Furan-Derived β-Enamino Diketones: An Entry to Diastereoselective Synthesis of Polycyclic Pyrano[3,2-c]quinolin-5-one Derivatives

A series of 1,3-cyclodiketone- and tetrahydroepoxyisoindole-fused β-enamino dicarbonyl heterocycles were synthesized via a 1,4-diazabicyclo[2.2.2]octane-catalyzed, CH₃NO₂-mediated three-component reaction of 1,3-cyclodiketone, furfural, and allylamine in toluene. The target compounds were generated via the formation of β-enamino diketone as a key intermediate, followed by intramolecular Diels-Alder cycloaddition. The prepared molecules bearing a quinoline-2,4-dione moiety could be further brominated with N-bromosuccinimide and diastereoselectively reduced by NaBH₄ to afford pyrano[3,2-c]quinolin-5-one-derived heterocycles with six vicinal stereogenic centers.

Para toluenesulfonic acid-catalyzed one-pot, three-component synthesis of benzo[5,6]chromeno[3,2-c]quinoline compounds in aqueous medium

A new series of benzo[5,6]chromeno[3,2-c]quinoline derivatives were successfully synthesized using various arylglyoxal monohydrates, quinoline-2,4-dione, and β-naphthol in H2O:EtOH (2:1) as a green solvent in the presence of catalytic amounts p-toluenesulfonic acid as a mild catalyst under reflux conditions with high yields (83–92%). The reaction conditions were optimized in different solvents at variable thermal conditions, and the optimized reaction condition for this synthesis has been reported. The structures of all new products were defined by 1H-NMR, 13C-NMR, FT-IR, mass spectral data, and HRMS.

Preliminary Study on Antifungal Mechanism of Aqueous Extract of Cnidium monnieri Against Trichophyton rubrum

Trichoderma rubrum (T. rubrum) is one of the important pathogens because it is the cause of most dermatomycosis. The treatment of Trichophyton rubrum infection is time-consuming and very expensive; it is easy for the infections to reoccur, leading to therapeutic failures, persistence, and chronic infection. These issues have inspired researchers to study natural alternative therapies instead. Cnidium monnieri (L.), as a kind of traditional Chinese medicine, has a variety of pharmacological activities and a wide range of applications, so it has a high potential for researching and economic value. We detected the effect of aqueous extract of C. monnieri (L.) on the activity of T. rubrum by Cell Count Kit-8 assay (CCK-8), and we found that 128 and 256 μg/ml of aqueous extracts of C. monnieri (L.) co-cultured with T. rubrum for 24 h showed the inhibitory effect on T. rubrum. The results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that aqueous extract of C. monnieri (L.) damaged the T. rubrum. At the same time, mass spectrometry screening with T. rubrum before and after the treatment of 256 μg/ml of aqueous extracts of C. monnieri (L.) showed that 966 differentially expressed proteins were detected, including 524 upregulated differentially expressed genes (DEGs) and 442 downregulated DEGs. The most significantly downregulated protein was chitin synthase (CHS); and the results of qRT-PCR and Western blotting demonstrated that the expression level of CHS was downregulated in the 256 μg/ml group compared with the control group. The study showed that the aqueous extract of C. monnieri (L.) could destroy the morphology of mycelia and the internal structure of T. rubrum, and it could inhibit the growth of T. rubrum. The antifungal effect of aqueous extract of C. monnieri (L.) may be related to the downregulation of the expression of CHS in T. rubrum, and CHS may be one of the potential targets of its antifungal mechanism. We concluded that aqueous extract from C. monnieri (L.) may be a potential candidate for antifungal agents.

δ-Lactones-A New Class of Compounds That Are Toxic to E. coli K12 and R2-R4 Strains

Lactones are among the well-known organic substances with a specific taste and smell. They are characterized by antibacterial, antiviral, anti-inflammatory, and anti-cancer properties. In recent years, among this group of compounds, new biologically active substances have been searched by modifying the main (leading) structure with new analogs with stronger or different responses that may have a toxic effect on the cells of pathogenic bacteria and constitute an alternative to commonly used antibiotics. A preliminary study of δ-lactone derivatives as new potential candidates for antibacterial drugs was conducted. Particular emphasis was placed on the selection of the structure of lactones with the highest biological activity, especially those with fluorine in their structure as a substituent in terms of action on bacterial lipopolysaccharide (LPS) in the model strains of Escherichia coli K12 (without LPS in its structure) and R2–R4 (LPS of different lengths in its structure). In the presented studies, on the basis of the conducted MIC and MBC tests, it was shown that the antibacterial (toxic) activity of lactones depends on their structure and the length of the bacterial LPS in the membrane of specific strains. Moreover, oxidative damage of bacterial DNA isolated from bacteria after modification with newly synthesized compounds after application of the repair enzyme Fpg glycosylase was analyzed. The analyzed damage values were compared with the modification with appropriate antibiotics: ciprofloxacin, bleomycin, and cloxacillin. The presented research clearly shows that lactone derivatives can be potential candidates as substitutes for drugs, e.g., the analyzed antibiotics. Their chemical and biological activity is related to coumarin derivatives and the corresponding δ-lactone groups in the structure of the substituent. The observed results are of particular importance in the case of increasing bacterial resistance to various drugs and antibiotics, especially in nosocomial infections and neoplasms, and in the era of a microbial pandemic.

8-Hy-droxy-6-meth-oxy-7-(3-methyl-but-2-en-yloxy)coumarin (capensine)

The title coumarin derivative, C15H16O5, was isolated from the roots of Sophora japonica. The coumarin (2H-chromen-2-one) fragment is almost planar, with an r.m.s. deviation of 0.0356 Å. The carbon atom of the meth-oxy substituent is coplanar with the benzo-pyran oxa-heterocycle. The 3-methyl-but-2-en-yloxy group is disordered over two sets of sites with occupation factors of 0.920 (3) and 0.080 (3). In the crystal, mol-ecules are linked by O-H⋯O and C-H⋯O hydrogen bonds into chains propagating along the [101] direction.

Crystal structure of 3-acetyl-6-bromo-4-hydroxy-2H-chromen-2-one, C11H7BrO4

C11H7BrO4, triclinic, P1̄ (no. 2), a = 4.3164(5) Å, b = 10.7922(12) Å, c = 11.1521(11) Å, α = 98.075(4)°, β = 100.741(4)°, γ = 95.325(5)°, V = 501.55(9) Å3, Z = 2, Rgt(F) = 0.0203, wRref(F2) = 0.0544, T = 200(2) K.

Structural tuning enables piezochromic and photochemical properties in N-aryl-β-enaminones

An efficient synthesis of N-aryl-β-enaminones via Et₃N-mediated, one-pot three-component reaction of 4-hydroxycoumarin/dimedone, β-nitrostyrene/2-(2-nitrovinyl)thiophene, and arylamine in toluene under refluxed conditions is herein presented. Some prepared compounds were found to exhibit piezochromic properties. The XRD and SEM measurements of the piezochromic compound showed substantial crystal packing and morphology changes before and after grinding. Further, one prepared compound was found to be light-sensitive and can be converted to a furo[3,2-b]pyridin-2(4H)-one derivative upon UV irradiation. A plausible mechanism for this photochemical reaction was proposed.

N-Aryl-β-enaminones are synthesized via Et₃N-mediated, one-pot three-component reaction of 4-hydroxycoumarin/dimedone, β-nitrostyrene/2-(2-nitrovinyl)thiophene and arylamine, and their piezochromic behavior and photosensitivity explored.

Fluorescence solvatochromism and modulated anticholinergic activity of novel coumarin compounds sequestered in human serum albumin nanocavities

The antagonistic effect of the HSA matrix towards the acetylcholinesterase inhibition potencies of novel coumarin compounds is probed by multi-spectroscopic techniques.

Drugs currently under investigation for the treatment of invasive candidiasis

INTRODUCTION

The widespread implementation of immunosuppressants, immunomodulators, hematopoietic stem cell transplantation and solid organ transplantation in clinical practice has led to an expanding population of patients who are at risk for invasive candidiasis, which is the most common form of fungal disease among hospitalized patients in the developed world. The emergence of drug-resistant Candida spp. has added to the morbidity associated with invasive candidiasis and novel therapeutic strategies are urgently needed. Areas covered: In this paper, we explore investigational agents for the treatment of invasive candidiasis, with particular attention paid to compounds that have recently entered phase I or phase II clinical trials. Expert opinion: The antifungal drug development pipeline has been severely limited due to regulatory hurdles and a systemic lack of investment in novel compounds. However, several promising drug development strategies have recently emerged, including chemical screens involving Pathogen Box compounds, combination antifungal therapy, and repurposing of existing agents that were initially developed to treat other conditions, all of which have the potential to redefine the treatment of invasive candidiasis.

Highly enantioselective synthesis of dihydrocoumarin-fused dihydropyrans via the phosphine-catalyzed [4 + 2] annulation of allenones with 3-aroylcoumarins

Phosphine-catalyzed [4 + 2] annulation between 3-aroylcoumarins and allenones has been developed. In the presence of a dipeptide phosphine catalyst 7, dihydrocoumarin-fused dihydropyrans were prepared in high yields and with excellent enantioselectivities.

Hydrogen Peroxide Scavenging Activity of Novel Coumarins Synthesized Using Different Approaches

New derivatives of 7-hydroxy-4-methylcoumarin were synthesized using a chemical method and a microwave-assisted method to compare the feasibility, reaction times, and yields of the product. The newly synthesized coumarins were characterized by different spectroscopic techniques (FT-IR and NMR) and micro-elemental analysis (CHNS). In vitro antioxidant activities of these compounds were evaluated against hydrogen peroxide and were compared with standard natural antioxidant, vitamin C. Our results reveal that these compounds exhibit excellent radical scavenging activities.

ANTIOXIDANT ACTIVITY OF AMINOTHIAZOL HYDROXYCOUMARIN DERIVATIVES

In this work, the antioxidant properties of the series of 10 aminothiazol hydroxyl coumarin derivatives have been investigated with DFT/B3LYP method. For these antioxidants all reaction enthalpies related to HAT, SPLET, SET-PT mechanisms were calculated in the gas phase and polar solvents. Based on calculated reaction enthalpies (BDE, IP and PA values) the derivations 2, 3 and 4 have the highest antioxidant activity among the studied compounds. Calculated results show that derivations 7, 5 and 6 have the lowest antioxidant activity. The observed theoretical trends for antioxidant activities of studied compounds were similar to trends of previous experimental studies that OH50, TAC50, IC50, CE50 values have been used as a benchmark for measuring the antioxidant properties of these compounds. These results can be useful in synthesis of novel aminothiazol hydroxycoumarin derivatives with high antioxidant activity. Calculated results show that BDE, PA and IP values of studied derivations have linear dependence with structure parameters such as R( O – H ), q( O ) and E HOMO . These observed linear dependences can be useful in synthesis of novel aminothiazol hydroxyl coumarin derivatives with high antioxidant activity. For studied compounds, results indicated that the SPLET and HAT mechanisms represent the thermodynamically preferred mechanism both, in solvent and the gas phase.

DABCO and Bu3P catalyzed [4 + 2] and [3 + 2] cycloadditions of 3-acyl-2H-chromen-ones and ethyl 2,3-butadienoate

DABCO-catalyzed [4 + 2] and Bu(3)P-catalyzed [3 + 2] cycloadditions between 3-acyl-2H-chromen-ones and ethyl 2,3-butadienoate were developed for the synthesis of dihydropyran-fused and cyclopenten-fused chromen-2-ones with high regio- and stereo-selectivities, respectively. The synthetic procedures have the advantages of mild reaction conditions, convenient handling and good atom economy as well as a wide substrate scope, which make this method useful for the synthesis of potentially biologically active dihydropyran-fused and cyclopenten-fused chromen-2-ones derivatives. Possible reaction mechanisms have also been proposed on the basis of previous literature and our investigation.

FT-IR, FT-Raman and UV-Vis spectra and DFT calculations of 3-cyano-4-methylcoumarin

The vibrational and electronic spectra of 3-cyano-4-methylcoumarin (3C4MC) are reported and discussed. In this work the structural properties, vibrational frequencies and electronic spectra of 3C4MC have been investigated extensively using density functional theory (DFT) employing B3LYP exchange correlation with the normal basis level 6-31G(d,p). NBO and HOMO, LUMO analysis has been carried out. The geometries and normal modes of vibrations obtained from B3LYP calculations are in good agreement with the experimentally observed data.

Biochemical and pharmacological evaluation of 4-hydroxychromen-2-ones bearing polar C-3 substituents as anticoagulants

The objective of this study was to investigate in vitro and in vivo anticoagulant activity of sixteen 4-hydroxycoumarin derivatives bearing polar C-3 scaffolds. The activity was evaluated by measuring prothrombin time. Enhanced anticoagulant activity in vitro was observed for all tested compounds. Upon successive administration of 0.5 mg/kg of body weight to adult Wistar rats, over a period of five days, four derivatives (2b, 4c, 5c and 9c) presented anticoagulant activity in vivo. The most active compound was 2b, with PT = 30.0 s. Low or non-toxic effects in vivo were determined based on the catalytic activity of liver enzymes and the concentration of bilirubin, iron and proteins. Metabolic pathways of the most active compounds in vivo were determined after GC/MS analysis of collected rat urine samples. The excretion occurs by glucuronidation of 7-hydroxy forms of tested derivatives. In vivo results were described using PLS-based CoMFA and CoMSIA 3D-QSAR studies, which showed CoMFA-SE (q(2) = 0.738) and CoMSIA-SEA (q(2) = 0.763) to be the statistically most relevant models. Furthermore, molecular docking and DFT mechanistic studies performed on the rat VKORC1 homology model revealed interactions between the 4-OH coumarin group in the form of phenolic anion and the Cys135 catalytic site in the transition state.

In vitro antioxidant activity of selected 4-hydroxy-chromene-2-one derivatives-SAR, QSAR and DFT studies

The series of fifteen synthesized 4-hydroxycoumarin derivatives was subjected to antioxidant activity evaluation in vitro, through total antioxidant capacity, 1,1-diphenyl-2-picryl-hydrazyl (DPPH), hydroxyl radical, lipid peroxide scavenging and chelating activity. The highest activity was detected during the radicals scavenging, with 2b, 6b, 2c, and 4c noticed as the most active. The antioxidant activity was further quantified by the quantitative structure-activity relationships (QSAR) studies. For this purpose, the structures were optimized using Paramethric Method 6 (PM6) semi-empirical and Density Functional Theory (DFT) B3LYP methods. Bond dissociation enthalpies of coumarin 4-OH, Natural Bond Orbital (NBO) gained hybridization of the oxygen, acidity of the hydrogen atom and various molecular descriptors obtained, were correlated with biological activity, after which we designed 20 new antioxidant structures, using the most favorable structural motifs, with much improved predicted activity in vitro.

Design of novel 4-hydroxy-chromene-2-one derivatives as antimicrobial agents

This paper presents the design of novel 4-hydroxy-chromene-2 one derivatives, based on previously obtained minimal inhibitory concentration values (MICs), against twenty four microorganism cultures, gram positive and negative bacteria and fungi. Two of our compounds, 3b (MIC range 130-500 microg/mL) and 9c (31.25-62.5 microg/mL), presented high potential antimicrobial activity. The compound 9c had equal activity to the standard ketoconazole (31.25 microg/mL) against M. mucedo. Enlarged resistance of S. aureus, E. coli and C. albicans on the effect of potential drugs and known toxicity of coumarin antibiotics, motivated us to establish SAR and QSAR models of activity against these cultures and correlate biological activity, molecular descriptors and partial charges of functional groups to explain activity and use for the design of new compounds. The QSAR study presents essential relation of antimicrobial activity and dominant substituents, 4-hydroxy, 3-acetyl and thiazole functional groups, also confirmed through molecular docking. The result was ten new designed compounds with much improved predicted inhibition constants and average biological activity.