Synthesis, in-vitro antibacterial, antifungal, and molecular modeling of potent anti-microbial agents with a combined pyrazole and thiophene pharmacophore

A Structural and In Silico Investigation of Potential CDC7 Kinase Enzyme Inhibitors

A crucial role in the regulation of DNA replication is played by the highly conserved CDC kinase. The CDC7 kinase could serve as a target for therapeutic intervention in cancer. The primary heterocyclic substance is pyrazole, and its derivatives offer great potential as treatments for cancer cell lines. Here, we synthesized the two pyrazole derivatives: 4-(2-(4-chlorophenyl)hydrazinyl)-5-methyl-2-tosyl-1H-pyrazol-3(2H)-one (PYRA-1) and 4-(2-(2,4-difluorophenyl)hydrazinyl)-5-methyl-2-tosyl-1H-pyrazol-3(2H)-one (PYRA-2). The structural confirmation of both the compounds at the three-dimensional level is characterized using single crystal X-ray diffraction and density functional theory. Furthermore, the in silico chemical biological properties were derived using molecular docking and molecular dynamics (MD) simulations. PYRA-1 and PYRA-2 crystallize in the P-1 (a = 8.184(9), b = 14.251(13), c = 15.601(15), α = 91.57(8), β = 97.48(9), 92.67(9), V = 1801.1(3) 3, and Z = 2) and P21/n (a = 14.8648(8), b = 8.5998(4), c = 15.5586(8), β = 116.47(7), V = 1780.4(19) 3, and Z = 4), space groups, respectively. In both PYRA-1 and PYRA-2 compounds, C-H···O intermolecular connections are common to stabilize the crystal structure. In addition, short intermolecular interactions stabilizes with C-H···π and π-π stacking. Crystal packing analysis was quantified using Hirshfeld surface analysis resulting in C···H, O···H, and H···H contacts in PYRA-1 exhibiting more contribution than in PYRA-2. The conformational stabilities of the molecules are same in the gas and liquid phases (water and DMSO). The docking scores measured for PYRA-1 and PYRA-2 with CDC7 kinase complexes are -5.421 and -5.884 kcal/mol, respectively. The MD simulations show that PYRA-2 is a more potential inhibitor than PYRA-1 against CDC7 kinase.

2D QSAR, Design, and in Silico Analysis of Thiophene-Tethered Lactam Derivatives as Antimicrobial Agents

BACKGROUND

A very high rate of resistance causes health-care-associated and community-acquired infections. E. coli is one of the nine pathogens of highest concern to most of the antibiotics and other class of antimicrobials.

OBJECTIVE

The objective of the present study is to develop novel thiophene derivatives using 2D QSAR and in silico approach for E. coli resistance.

METHODS

Substituted thiophene series reported by Nishu Singla et al., were taken for QSAR analysis. From the results, a set of 15 new compounds were designed. A complete in silico analysis has been done using PADEL, Autodock vina, Swiss ADME, Protox II software.

RESULTS

The designed compounds obey the Lipinski's rule of five and were known to have excellent inhibitory action (pIC50 values -0.87 to -1.46) which is similar to the most active compound of the data set (pIC50 -0.69) taken for the study. The bioavailability score (0.65) with no toxicity representing that the designed compounds are suitable for oral administration.

CONCLUSION

The designed compounds are inactive for mutagenicity and cytotoxicity and ADMET studies states that these molecules are likely to be orally bioavailable and could be easily transported, diffused, and absorbed. So, the designed compounds will definitely serve as a lead antibacterial agent for E. coli resistance.

New pyrazolylpyrazoline derivatives as dual acting antimalarial-antileishamanial agents: synthesis, biological evaluation and molecular modelling simulations

Promising inhibitory activities of the parasite multiplication were obtained upon evaluation of in vivo antimalarial activities of new pyrazolylpyrazoline derivatives against Plasmodium berghei infected mice. Further evaluation of 5b and 6a against chloroquine-resistant strain (RKL9) of P. falciparum showed higher potency than chloroquine. In vitro antileishmanial activity testing against Leishmania aethiopica promastigote and amastigote forms indicated that 5b, 6a and 7b possessed promising activity compared to miltefosine and amphotericin B deoxycholate. Moreover, antileishmanial activity reversal of the active compounds via folic and folinic acids showed comparable results to the positive control trimethoprim, indicating an antifolate mechanism via targeting leishmanial DHFR and PTR1. The compounds were non-toxic at 125, 250 and 500 mg/kg. In addition, docking of the most active compound against putative malarial target Pf-DHFR-TS and leishmanial PTR1 rationalised the observed activities. Molecular dynamics simulations confirmed a stable and high potential binding of 7a against leishmanial PTR1.

Thiophene-containing compounds with antimicrobial activity

Thiophene, as a member of the group of five-membered heterocycles containing one heteroatom, is one of the simplest heterocyclic systems. Many synthetic strategies allow the accurate positioning of various functionalities onto the thiophene ring. This review provides a comprehensive, systematic and detailed account of the developments in the field of antimicrobial compounds featuring at least one thiophene ring in their structure, over the last decade.

Design, synthesis and antimicrobial activity of novel 2-aminothiophene containing cyclic and heterocyclic moieties

One of the major challenges in the community and healthcare was an impedance of pathogenic bacteria to antibiotics. This work developed 2-aminothiophene derivatives as novel antimicrobial agents. Various 2-aminothiophene derivatives (3a-f, 5a-c, 6a, b, 7, 8a, b and 9) with cyclic and heterocyclic moieties at 5-position were synthesized, and characterized using NMR, IR, and mass spectroscopic techniques. The newly synthesized compounds were evaluated for their antimicrobial activity against bacteria S. pneumoniae, B. subtilis, P. aeruginosa, E. coli, and fungi A. fumigatus, S. mracemosum, G. candidum, C. albicans. Compound 3a with OH group at para position of phenyl ring exhibited significant antibacterial activity stronger than that of the drug standards Ampicillin and Gentamicin. Compound 6b possess pyrazole ring and compound 9 bearing pyridine ring showed promising antifungal activity compare to the standard drug Amphotericin B. The remaining compounds exhibited good to moderate inhibitory activities. In summary, the results suggest that the compounds from 2-aminothiophene derivatives can be used as antimicrobial agents.

Design, Synthesis and Antimicrobial Evaluation of 1,3,4‐Oxadiazole/1,2,4‐Triazole‐Substituted Thiophenes

The increasing level of antimicrobial resistance in pathogenic bacteria, together with the lack of new potential drug scaffolds in the pipeline, make the problem of infectious diseases a major public health concern. Thus, in this context, a novel series of 1,3,4‐oxadiazole‐substituted thiophenes (4 a–m) and 1,2,4‐triazole (6 a–m) substituted thiophene derivatives were synthesized. Characterization of all the synthesized derivatives was done by various spectroscopic techniques such as 1H NMR, 13C NMR spectroscopy and mass spectrometry, and evaluated for antimicrobial activity against various pathological strains using broth dilution and disc diffusion method. In particular, compound 6 e and 4 e exhibited significant inhibitory potential with MIC ranging from 2–7 μg mL−1 against S. aureus, B. subtilis, P. aeruginosa and E. coli. Additionally, compound 6 e was found to be highly potent against methicillin resistant S. aureus (MRSA; MIC=2 μg mL−1). Molecular docking studies were also performed to confer the possible mode of action and association studies indicate the binding of potent active compound with DHFR enzyme (Ka=2.10×103 M−1). Further, the mechanism of action has also been explored by atomic force microscopy (AFM), which reveals the bacterial cell wall deformity and cell wall rupturing that may lead to bacteria cell death. Additionally, in silico ADME prediction study suggested the drug like properties of active compounds.

Synthesis of novel Schiff bases using 2-Amino-5-(3-fluoro-4-methoxyphenyl)thiophene-3-carbonitrile and 1,3-Disubstituted pyrazole-4-carboxaldehydes derivatives and their antimicrobial activity

2-Amino-5-(3-fluoro-4-methoxyphenyl)thiophene-3-carbonitrile have been synthesized from 1-(3-fluoro-4-methoxyphenyl)ethanone, malononitrile, a mild base and sulfur powder using Gewald synthesis technique and the intermediate was treated with 1,3-disubstituted pyrazole-4-carboxaldehyde to obtain the novel Schiff bases. 1,3-disubstituted pyrazole-4-carboxaldehyde derivatives have been synthesized by Vilsmeier-Haack reaction in the course of a multi-step reaction. The structure of novel compounds were established on the basis of their elemental analyses IR, ¹H NMR, ¹³C NMR, and mass spectral data and then screened for their in vitro antimicrobial activity. Among them 5a, 5c, 5f and 5h showed excellent activity when compared to other derivatives. Remaining derivatives showed moderate activity.

Synthesis, molecular modeling and biological screening of some pyrazole derivatives as antileishmanial agents

Aim: Novel open chain and cyclized derivatives containing pyrazole scaffold were designed, synthesized and evaluated as antileishmanial compounds. Methodology & results: In silico reverse docking experiment suggested Leishmania major pteridine reductase (Lm-PTR1) as a putative target for the synthesized compounds. In vitro antileishmanial screening against L. major promastigotes and amastigotes using miltefosine and amphotericin B as references showed that the majority of the compounds displayed activity higher than miltefosine. Compounds 3i and 5 showed the highest antileishmanial activity with IC50 values of 1.45 ± 0.08 μM and 2.30 ± 0.09 μM, respectively, for the amastigote form. In silico drug-likeness and toxicity predictions showed acceptable profiles for most of the compounds, which were validated by experimental toxicity studies. Conclusion: This study offers promising entities for antileishmanial activity.

Novel Pyrazole-Hydrazone Derivatives Containing an Isoxazole Moiety: Design, Synthesis, and Antiviral Activity

In this study, a series of novel pyrazole-hydrazone derivatives containing an isoxazole moiety were synthesized. Antiviral bioassays indicated that some of the title compounds exhibited better in vivo antiviral activities against tobacco mosaic virus (TMV). In particular, compounds 6a, 6c and 6q exhibited the best curative activity, protection activity, and inactivation activity against TMV, respectively, which were superior to those of Ningnanmycin. This study demonstrated that this series of novel pyrazole-hydrazone derivatives containing an isoxazole amide moiety could effectively control TMV.

One-pot sequential synthesis of tetrasubstituted thiophenes via sulfur ylide-like intermediates

Herein, we describe a novel approach for the practical synthesis of tetrasubstituted thiophenes 8. The developed method was particularly used for the facile preparation of thienyl heterocycles 8. The mechanism for this reaction is based on the formation of a sulfur ylide-like intermediate. It was clearly suggested by (i) the intramolecular cyclization of ketene N,S-acetals 7 to the corresponding thiophenes 8, (ii) 1H NMR studies of Meldrum's acid-substituted aminothioacetals 9, and (iii) substitution studies of the methoxy group on Meldrum's acid containing N,S-acetals 9b. Notably, in terms of structural effects on the reactivity and stability of sulfur ylide-like intermediates, 2-pyridyl substituted compound 7a exhibited superior properties over those of others.

Antimicrobial activity of thiophene derivatives derived from ethyl (E)-5-(3-(dimethylamino)acryloyl)-4-methyl-2-(phenylamino)thiophene-3-carboxylate

Background

The thiophene nucleus has been recognized as an important entity in the synthesis of heterocyclic compounds with promising pharmacological characteristics.

Results

A number of new heterocyclic compounds incorporating thiophene species have been prepared from the titled enaminone via the reaction with different nucleophiles and electrophiles. The structure elucidation of the designed compounds was derived from their spectral information. The results of antimicrobial activity of the prepared compounds revealed that derivatives 7b and 8 exhibited activity comparable to the standard drugs ampicillin and gentamicin for all tested bacteria species. Additionally, compound 3 displayed potent activity against Aspergillus fumigates, whereas compounds 5, 6, and 7a showed good activity against Syncephalastrum racemosum.

Conclusions

We have synthesized a number of new thiophene-containing compounds. The results of antimicrobial activity of the prepared compounds revealed that changing the substituents at position-2 of thiophene ring significantly affect their biological activity. The pyridine side chain derivatives in compounds 7a, 7b and 8 showed excellent antimicrobial activity.

Synthesis, characterization, X-ray structure, computational studies, and bioassay of novel compounds combining thiophene and benzimidazole or 1,2,4-triazole moieties

BACKGROUND

Due to their interesting and versatile biological activity, thiophene-containing compounds have attracted the attention of both chemists and medicinal chemists. Some of these compounds have anticancer, antibacterial, antiviral, and antioxidant activity. In addition, the thiophene nucleus has been used in the synthesis of a variety of heterocyclic compounds.

RESULTS

In the present work, two novel thiophene-containing compounds, 4-phenyl-2-phenylamino-5-(1H-1,3-a,8-triaza-cyclopenta[α]inden-2-yl)-thiophene-3-carboxylic acid ethyl ester (3) and 5-(1H-Imidazo[1,2-b] [1,2,4] triazol-5-yl)-4-phenyl-2-phenylamino-thiophene-3-carboxylic acid ethyl ester (4), have been synthesized by reaction of 5-(2-bromo-acetyl)-4-phenyl-2-phenylaminothiophene-3-carboxylic acid ethyl ester (2) with 2-aminobenzimidazole and 3-amino-1H-1,2,4-triazole in the presence of triethylamine, respectively. Compound 2, on the other hand, was prepared by bromination of 5-acetyl-4-phenyl-2-phenylaminothiophene-3-carboxylic acid ester (1). Structures of the newly prepared compounds were confirmed by different spectroscopic methods such as ¹H-NMR, ¹³C-NMR, and mass spectrometry, as well as by elemental analysis. Furthermore, bromination of compound 1 led to the formation of two constitutional isomers (2a and 2b) that were obtained in an 80:20 ratio. Molecular structures of 2b were confirmed with the aid of X-ray crystallography. Compound 2 was crystallized in the triclinic, P-1, a = 8.8152 (8) Å, b = 10.0958 (9) Å, c = 12.6892 (10) Å, α = 68.549 (5)°, β = 81.667 (5)°, γ = 68.229 (5)°, V = 976.04 (15) Å³, Z = 2, and was found in two isomeric forms regarding the position of the bromine atom. The antibacterial and antifungal activities of the prepared compounds were evaluated.

CONCLUSIONS

Three new thiophene derivatives were synthesized in good yield. Antimicrobial screening revealed that compound 3 was a promising candidate as a potential antibacterial and antifungal agent; it exhibits remarkable activity against the studied bacterial strains, especially the gram negative bacteria E. coli in addition to some fungi. More work is needed to evaluate its safety and efficacy.

Crystal structure of 1-(5-benzoyl-4-methyl-2-(phenylamino)thiophen-3-yl)ethan-1-one, a structure with Z′ = 6, C20H17NO2S

C20H17NO2S, triclinic, P1̅ (no. 2), a = 8.2737(5) Å, b = 16.6403(9) Å, c = 17.733(1) Å, α = 86.372(3)°, β = 86.317(4)°, γ = 78.607(3)°, V = 2385.2(2) Å3, Z = 6, R gt (F) = 0.0429, wR ref (F 2 ) = 0.1086, T = 100 K.

Heterocycles 38. Biocatalytic Synthesis of New Heterocyclic Mannich Bases and Derivatives

This paper describes the biocatalytic synthesis of new Mannich bases containing various heterocyclic rings (thiazole, furane, thiophene, pyridine) by applying the lipase catalyzed trimolecular condensation of the corresponding heterocyclic aldehydes with acetone and primary aromatic amines, in mild and eco-friendly reaction conditions. The obtained Mannich bases were acylated to their corresponding N-acetyl derivatives. All compounds were characterized by ¹H-NMR, ¹³C-NMR and MS spectrometry.