Synthesis of thiophene-pyrazole conjugates as potent antimicrobial and radical scavengers

The current study presents the synthesis of thiophene-appended pyrazoles through 3+2 annulations of chalcones 3(a-g)with aryl hydrazine hydrochlorides 4(a-d) in acetic acid (30%) under reflux conditions produced the thiophene-pyrazole hybrids 5(a-g) in good yields. Structures of synthesized new pyrazoles were confirmed by spectral studies, and elemental analysis. Further, preliminary biological evaluation studies show that compounds 5b and 5f having chloro substitution only in the thiophene ring exhibited excellent inhibition (12.5-25.0 µg/mL) against all the tested organisms in comparison with that of the standard. Compounds, 5a, 5c and 5g having electronegative chloro substitutions each in the aromatic and thiophene rings showed excellent (12.423-31.213 µg mL-1) DPPH radical scavenging potencies. The synthesis of pyrazoline derivatives and the efficacy of some of the synthesized molecules as antimicrobial and antioxidant agents validate the significance of this study

Synthesis and biological evaluation of novel formyl-pyrazoles bearing coumarin moiety as potent antimicrobial and antioxidant agents

A series of coumarin appended formyl-pyrazoles 14–18 were synthesized by a simple and accessible approach. The reaction of 8-acetyl-4-methyl-7-hydroxy coumarin 3 and phenyl hydrazine hydrochlorides 4–8 produces the intermediate compounds 8-acetyl-4-methyl-7-hydroxy coumarin hydrazones 9–13. The reaction of compounds 9–13 and DMF in the presence of POCl3 yielded formyl-pyrazoles bearing coumarin moiety 14–18 in good yield. The synthesized new compounds 14–18 and the intermediates 8-acetyl-4-methyl-7-hydroxy coumarin hydrazones 9–13 prepared were screened in vitro for their antibacterial, antifungal antioxidant activities. The compounds 12 and 17 having chloro substitution exhibited promising antifungal and antibacterial activity against the different organisms tested. The compound 17 showed remarkable DPPH radical scavenging ability

SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF NOVEL FUSED PYRAZOLES

Objective: The aim of the present work was to synthesize fused pyrazoles and examine them for their in vitro antimicrobial activity.Methods: The formyl pyrazoles were synthesized by Vilsmeier–Haack reaction from o-hydroxy acetophenone hydrazones. The pyrazoles on oxidative cyclisation in the presence of ethanol and catalytic amount of H2SO4 yielded pyrano [4,3-c] pyrazoles. The structures of the synthesized derivatives were confirmed by Mass, 1H NMR and elemental analysis. The synthesized new pyranopyrazoles were screened for their antimicrobial activity by broth dilution technique.Results: The results of the antimicrobial assay revealed that the compound 4b having chloro substitution showed good activity against different microorganisms tested.Conclusion: It is noteworthy that the compounds synthesized by a simple and accessible procedure leads to a molecules of promising antimicrobial activity. Â

Synthesis of novel coumarin appended bis(formylpyrazole) derivatives: Studies on their antimicrobial and antioxidant activities

A series of novel coumarin pyrazole hybrids of biological interest were synthesized from the hydrazones, carbazones and thiocarbazones via Vilsmeier Haack formylation reaction. These intermediates and formyl pyrazoles were evaluated for antimicrobial and antioxidant activities. Among the series, compounds 6g and 6h showed excellent antimicrobial activity against different bacterial and fungal strains and compounds 7g, 7h were found to be potent antioxidant agents in both DPPH and hydroxyl radical scavenging assays. Further, detailed quantitative structure–activity relationship (QSAR) analysis indicated the molecular parameters that contribute to increased potency of inhibition. The above findings would further encourage our understanding in employing coumarin pyrazole hybrids as potential antibiotic agents for treating infections caused by pathogenic microbes and fungi. Further, it also paves the way for exploration of these compounds as potential therapeutic agents to treat conditions arising because of excessive oxidative damage

Environmentally benign synthesis of substituted pyrazoles as potent antioxidant agents, characterization and docking studies

Oxidative stress is an important cause of neurogenerative diseases; treatment with a reliable antioxidant with no side effects is a potential tool to overcome with such diseases. The aim of this study is to explore new and effective antioxidants and their mechanism; in this context, the manuscript demonstrates the greener approach for the synthesis of series of novel thiophene-pyrazole hybrids,5(a-m) through 3 + 2] annulation of chalcones,3(a-g) and phenylhydrazine hydrochloride,4(a-b) in citrus extract medium in the presence of tetrabutylammonium bromide. The structures were confirmed by spectroscopic and crystallographic studies and further screened in vitro for their free radical scavenging activities. Preliminary assessment results show that, among the synthesized series, compounds5c,5d,5f,5i,5j,5l, and5mhave potent antioxidant activities. Docking studies reveal that the ligands5e,5f,5m, and5qbind to superoxide dismutase at the Cu-Zn domain and thereby increase its activity and reduce reactive oxygen species; therefore, these ligands might be better antioxidant molecules which could down and regulate the oxidation stress within the body

Synthesis of lignan conjugates via cyclopropanation: Antimicrobial and antioxidant studies

Ethyl 2-(4-methoxyphenyl)-3-(thiophene-2-carbonyl)cyclopropanecarboxylates 2(a–f) and ethyl 4-aryl-7-oxo-4,5,6,7-tetrahydrobenzobthiophene-5-carboxylates 4(a–f) were synthesized by simple procedure. The synthesized new compounds were screened in vitro for their antimicrobial and antioxidant activities. The compounds 2b and 4f showed excellent antibacterial activity; while 2b and 4f showed remarkable antifungal properties. The results of antioxidant activity studies revealed that compounds 4b and 4f manifested profound antioxidant potential. The docking studies were done for the final compounds. The ADME result indicates that all these molecules possess pharmaceutical properties in the range of 95% of drugs