Synthesis and antimicrobial studies of furyl based new bispyrazolines linked via aliphatic chains

Antibacterial potential of chalcones and its derivatives against Staphylococcus aureus

Chalcones are natural substances found in the metabolism of several botanical families. Their structure consists of 1,3-diphenyl-2-propen-1-one and they are characterized by having in their chains an α, β-unsaturated carbonyl system, two phenol rings and a three-carbon chain that unites them. In plants, Chalcones are mainly involved in the biosynthesis of flavonoids and isoflavonoids through the phenylalanine derivation. This group of substances has been shown to be a viable alternative for the investigation of its antibacterial potential, considering the numerous biological activities reported and the increase of the microbial resistance that concern global health agencies. Staphylococcus aureus is a bacterium that has stood out for its ability to adapt and develop resistance to a wide variety of drugs. This literature review aimed to highlight recent advances in the use of Chalcones and derivatives as antibacterial agents against S. aureus, focusing on research articles available on the Science Direct, Pub Med and Scopus data platforms in the period 2015-2021. It was constructed informative tables that provided an overview of which types of Chalcones are being studied more (Natural or Synthetic); its chemical name and main Synthesis Methodology. From the analysis of the data, it was observed that the compounds based on Chalcones have great potential in medicinal chemistry as antibacterial agents and that the molecular skeletons of these compounds as well as their derivatives can be easily obtained through substitutions in the A and B rings of Chalcones, in order to obtain the desired bioactivity. It was verified that Chalcones and derivatives are promising agents for combating the multidrug resistance of S. aureus to drugs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03398-7.

A Compendium of the Most Promising Synthesized Organic Compounds against Several Fusarium oxysporum Species: Synthesis, Antifungal Activity, and Perspectives

Vascular wilt caused by F. oxysporum (FOX) is one of the main limitations of producing several agricultural products worldwide, causing economic losses between 40% and 100%. Various methods have been developed to control this phytopathogen, such as the cultural, biological, and chemical controls, the latter being the most widely used in the agricultural sector. The treatment of this fungus through systemic fungicides, although practical, brings problems because the agrochemical agents used have shown mutagenic effects on the fungus, increasing the pathogen's resistance. The design and the synthesis of novel synthetic antifungal agents used against FOX have been broadly studied in recent years. This review article presents a compendium of the synthetic methodologies during the last ten years as promissory, which can be used to afford novel and potential agrochemical agents. The revision is addressed from the structural core of the most active synthetic compounds against FOX. The synthetic methodologies implemented strategies based on cyclo condensation reactions, radical cyclization, electrocyclic closures, and carbon-carbon couplings by metal-organic catalysis. This revision contributes significantly to the organic chemistry, supplying novel alternatives for the use of more effective agrochemical agents against F. oxysporum.

Recent Highlights on the Synthesis of Pyrazoles with Antimicrobial Activity

Background:

Heterocyclic compounds containing nitrogen atoms such as pyrazoles have a long history and applicability in the field of medicinal chemistry. Many compounds containing pyrazole moiety have been reported in the available literature for their prominent biological activities, including antimicrobial activity against different microorganisms. Over the years, there has been a concern with the many health problems associated with the dramatic increase of microbial infections and resistance to standard drugs, so there is a need for the development of more effective antimicrobial agents. Pyrazoles and their derivatives are promising candidates to bypass these problems with good safety profiles, and there is a wide range of synthetic methodologies for their obtainment. This review aims to compact a literature survey (2012-2017) very informative and helpful for researchers who wish to study or continue the development of new, potent and broad-spectrum antimicrobial compounds.

Methods:

This review encompasses reports on the synthesis and antimicrobial evaluation of synthetic pyrazoles from the year 2012 to 2017, which were extracted from bibliographic databases such as PubMed, scielo, sciencedirect, scifinder, and scopus. The main keywords in our search were “pyrazole” and “antimicrobial activity”, in which we made efforts to include synthetic and biological methodologies that can be useful for laboratories of different levels of infrastructure. Moreover, inclusion/ exclusion criteria was applied to select quality reports which could demonstrate different tools of antimicrobial evaluation, focusing on the advances made in the area, such as evaluation in silico and exploration of the possible mechanism of action for active compounds.

Results:

Thirty-four papers were included in this work, which was displayed chronologically from the year 2012 to 2017 in order to enhance the advances made in the area, with at least five reports from each year. We found that the most commonly tested bacterial strains are Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and from the year 2016 onwards Mycobacterium tuberculosis. The most common tested fungal strains are Candida albicans, Aspergillus flavus, and Aspergillus niger. The majority of articles expressed the antimicrobial results as a zone of inhibition, leading to the determination of the Minimum Inhibitory Concentration (MIC) and a probable mechanism of action for the most prominent compounds, considering cytotoxicity. Aromatic aldehydes and ketones are key reactants to obtain important precursors for the synthesis of pyrazoles, such as chalcones, together with alkyl or phenylhydrazines and thiosemicarbazide. A great variation in the reported MICs was found as there is no standard maximum limit, but many compounds exhibited antimicrobial activity comparable or better than standard drugs, from which 10 reports active compounds with MIC lower than 5 μg mL-1.

Conclusion:

The findings of this work support the importance of pyrazole moiety in the structure of antimicrobial compounds and the versatility of synthetic methodologies to obtain the target products. Results clearly indicate that they are attractive target compounds for new antimicrobial drugs development. We hope that this information will guide further studies on continuing the search for more effective, highly active antimicrobial agents.