Recent developments of chalcones as potential antibacterial agents in medicinal chemistry

Control of Bacterial Canker caused by Pseudomonas syringae pv. actinidiae (Psa) in kiwifruit plants by resinous exudates and extracts of Adesmia balsamica

BACKGROUND

Pseudomonas syringae pv. actinidiae (Psa) is the pathogen responsible for kiwifruit's bacterial canker, which produces significant economic losses. Effective treatments and measures to control this disease have not yet been found; it is currently controlled with many products containing heavy metals (especially copper) or antibiotics (especially streptomycin), which can cause serious phytotoxicity and antibacterial resistance problems. Therefore, it is essential to develop new strategies to control this disease by obtaining a product of natural origin of sustainable use, which is biodegradable and nontoxic to the environment, that could be used as biopesticide.

RESULTS

The ethyl acetate extract of Adesmia balsamica and the compound 2',4'-dihydroxychalcone (2,4-DHCH; 4) exhibited the same or similar antibacterial activity, respectively, as the positive control (commercial pesticide) at an effective concentration of 500 μg mL-1, on kiwifruit plants (Soreli variety) in vivo. Fluorescence microscopy revealed that one of the main modes-of-action by which it inhibits bacterial growth of Psa is by increasing membrane permeation, causing its disruption and intracellular alteration. Additionally, the application of the extract and 4 manages to control Psa bacterial canker disease by reducing gene expression related to the hrp W gene; Psa concentratiosn were specifically detected through real-time quantitative polymerase chain reaction (qPCR).

CONCLUSION

The ethyl acetate extract of A. balsamica effectively controls Psa in vitro and in vivo applied on kiwifruits plants, and therefore is a potential biopesticide for the control of bacterial canker in kiwifruit and potentially other crops. © 2025 Society of Chemical Industry.

Ultrafast excited-state dynamics of 4-hydroxychalcone: role of intramolecular charge transfer and photoacidity

Diarylketones such as benzophenones, oxybenzones, chalcones and their derivatives exhibit promising applications as UV filters/sunscreen agents due to their effective absorption in the UV region and dissipation through non-radiative pathways. However, elucidation of the underlying photoreactive mechanism is non-trivial due to the ultrafast lifetimes of transient species, involvement of non-adiabatic curve crossings among the potential surfaces, etc. In this context, we investigate the excited-state photoreaction dynamics of 4-hydroxychalcone (4-HC) under various environments through femtosecond-transient absorption (fs-TA), nanosecond-transient absorption (ns-TA), and femtosecond-fluorescence upconversion (fs-FL) measurements. Steady-state fluorescence measurements of 4-HC in the presence of 1-methylimidazole (MI)/tert-butylamine (TBA) exhibit dual band emission. The fs-TA measurements of 4-HC in the presence of MI/TBA exhibit distinct spectral and associated lifetimes as compared to 4-HC alone indicating a significant interaction of the hydroxyl proton with bases and influencing the reaction dynamics. The 4-HC:MI/TBA adduct undergoes excited-state intermolecular proton transfer within a time scale of ∼500 fs and subsequently relaxes back to the ground state through a long-lived triplet state. The experimental observations of excited-state reaction dynamics of 4-HC in the presence of MI/TBA bases have been well corroborated with the computational analysis.

Development of 1,2,3-triazole hybrids as multi-faced anticancer agents co-targeting EGFR/mTOR pathway and tubulin depolymerization

Novel 1,2,3-triazole hybrids bearing various substituents have been synthesized as potential anticancer agents. Ligand-based approach has been adopted to design these compounds relying on the hybridization of 1,2,3-triazole with α,β-unsaturated carbonyl, 5- and 6-membered heterocyclic scaffolds. All synthesized members were investigated for their cytotoxic potency against nine types comprising 60 panels of human cancerous cells by the US National Cancer Institute: Development Therapeutic Program (US_NCI_DTP). Among the tested members, 4b, 4e, and 4h showed prominent cytotoxic effects (> 80 % growth inhibition: GI) on a wide panel of tested cancer cell lines, mainly melanoma and colorectal cancer redeeming their selection for five dose testing. Presenting low nanomolar GI50 concentrations, two representative potent anticancer compounds 4b and 4e were subjected to cytotoxicity testing on colon normal cell (FHC) to investigate their safety window and they showed less toxicity to normal cells at the concentration required to produce anticancer effect. Furthermore, 4b and 4e were exposed to additional mechanistic studies in colorectal cancer cell HCT-116 suggesting multifaceted mechanisms of action. A study into the effects of cytotoxic chemicals 4b and 4e on cell cycle progression regulation showed triggered the arrest of cell cycles during the G1 and S phases. Moreover, 4b and 4e caused cell death mainly through apoptosis the thing that has been reinforced by the elevated Bax: Bcl2 ratio, as well as concentrations of caspases 3 and 9 within HCT-116. Further, both compounds showed prominent inhibition profiles against tubulin polymerization as well as EGFR catalytic activity reaching down to low-digit micromolar and sub-micromolar concentrations, respectively, as compared to positive reference controls. Compounds' impacts on gene expression of cancer-associated and EGFR-downstream signaling markers including TNFα, IL-6, and mTOR, were explored in HCT-116 highlighted significant downregulations versus the untreated cells. Docking studies demonstrated the specific fit of 4b and 4e into EGFR and the colchicine binding site of tubulin.

Direct β-C-H ketoalkylation of enaminoesters with cyclopropanols under metal-free conditions

A TEMPO-mediated β-ketoalkylation of enaminoesters with cyclopropanols under metal-free conditions is herein described. This reaction provides a straightforward and highly efficient route to β-keto alkyl substituted enaminoesters for the first time, which could be rapidly and efficiently converted into synthetically useful 2-alkoxycarbonyl functionalized 1,5-diketones. Moreover, the practicability of this protocol is successfully demonstrated by scale-up experiments and the late-stage functionalization of natural products and pharmaceutically relevant molecules.

Targeted inhibition of PqsR in Pseudomonas aeruginosa PAO1 quorum-sensing network by chalcones as promising antibacterial compounds

BACKGROUND

Pseudomonas aeruginosa's inherent and adapted resistance makes this pathogen a serious problem for antimicrobial treatments. Furthermore, its biofilm formation ability is the most critical armor against antimicrobial therapy, and the virulence factors, on the other hand, contribute to fatal infection and other recalcitrant phenotypic characteristics. These capabilities are harmonized through cell-cell communication called Quorum Sensing (QS), which results in gene expression regulation via three major interconnected circuits: las, rhl, and pqs system. Pqs circuit specificity in P. aeruginosa made this system an attractive target for antipseudomonal therapy. The current study focuses on novel chalcone derivatives that attenuate P. aeruginosa's pathogenicity by inhibiting the QS system. Chalcones are included in the flavonoid class of phenolic compounds. This family forms one of the greatest groups of bioactive natural products.

METHOD

The chalcone derivatives's potential activity against the QS system was evaluated through biofilm inhibition, decreased virulence factors production, and gene expression.

RESULTS

Among all the tested compounds, 5H and NMe2 chalcone derivatives reduced biofilm formation by 60.9% and 78.9%, respectively, and virulence factors production, including pyocyanin (decreased by 5H 30.9% and NMe2 30.7%) and pyoverdine (decreased by 5H 47.1% and NMe2 56.9%) and the QS gene expression (LasR, RhlR, and PqsR) more effectively than other derivatives.

CONCLUSION

These chalcone compounds can be used as a supplement besides antimicrobial chemotherapy to attenuate pseudomonas pathogenicity.

(E)-1-(3-(3-Hydroxy-4-Methoxyphenyl)-1-(3,4,5-Trimethoxyphenyl)allyl)-1H-1,2,4-Triazole and Related Compounds: Their Synthesis and Biological Evaluation as Novel Antimitotic Agents Targeting Breast Cancer

Background/Objectives: The synthesis of (E)-1-(1,3-diphenylallyl)-1H-1,2,4-triazoles and related compounds as anti-mitotic agents with activity in breast cancer was investigated. These compounds were designed as hybrids of the microtubule-targeting chalcones, indanones, and the aromatase inhibitor letrozole. Methods: A panel of 29 compounds was synthesized and examined by a preliminary screening in estrogen receptor (ER) and progesterone receptor (PR)-positive MCF-7 breast cancer cells together with cell cycle analysis and tubulin polymerization inhibition. Results: (E)-5-(3-(1H-1,2,4-triazol-1-yl)-3-(3,4,5-trimethoxyphenyl)prop-1-en-1-yl)-2-methoxyphenol 22b was identified as a potent antiproliferative compound with an IC50 value of 0.39 mM in MCF-7 breast cancer cells, 0.77 mM in triple-negative MDA-MB-231 breast cancer cells, and 0.37 mM in leukemia HL-60 cells. In addition, compound 22b demonstrated potent activity in the sub-micromolar range against the NCI 60 cancer cell line panel including prostate, melanoma, colon, leukemia, and non-small cell lung cancers. G2/M phase cell cycle arrest and the induction of apoptosis in MCF-7 cells together with inhibition of tubulin polymerization were demonstrated. Immunofluorescence studies confirmed that compound 22b targeted tubulin in MCF-7 cells, while computational docking studies predicted binding conformations for 22b in the colchicine binding site of tubulin. Compound 22b also selectively inhibited aromatase. Conclusions: Based on the results obtained, these novel compounds are suitable candidates for further investigation as antiproliferative microtubule-targeting agents for breast cancer.

Synthesis and Evaluation of Antibacterial and Antifungal Activities In vitro and In silico of Novel Morpholinoalkoxychalcones

INTRODUCTION

Chalcone compounds exhibit diverse bioactivities, attracting significant interest. Morpholine is a heterocycle commonly used in medicinal chemistry. It could enhance the potency, pharmacokinetics, and bioactivities of its compounds.

METHODS

Adding morpholine into the chalcone scaffold could help create new compounds with favorable bioactivities. In this study, a new parallel synthesis procedure has been developed. Using this procedure, 18 novel morpholinoalkoxychalcones have been successfully synthesized. They had chains with morpholine appended on ring A or ring B. All the synthesized compounds were evaluated for the antibacterial and antifungal activities by agar diffusion method on 5 bacteria and 2 fungi strains.

RESULTS

The compounds with good inhibition were determined with respect to the MIC values by the agar dilution method. Among the tested compounds, B.21 was found to be the best against E. faecalis, with an MIC value of 0.6 mM. B.43 with an MIC value of 2.04 mM has displayed its potential in inhibiting A. niger and C. albicans the best among other compounds.

CONCLUSION

The in silico study has revealed two targets to align with the in vitro results. Longer alkyl chains have enhanced the activity, along with the presence of OH, NH2, and halogen groups on both rings A and B.

Comprehensive Insight into Green Synthesis Approaches, Structural Activity Relationship, and Therapeutic Potential of Pyrazolic Chalcone Derivative

Pyrazolic chalcone exhibits diverse therapeutic activities, including anti-inflammatory, antioxidant, antimicrobial, antitumor, and anti-diabetic properties. Structural activity relationship (SAR) studies play a crucial role in understanding the molecular aspects governing their biological effects, guiding the rational design of derivatives with enhanced efficacy and reduced side effects. This review provides an overview of pyrazolic chalcone derivatives, emphasizing their synthesis through both conventional and green methods. In comparison, conventional synthesis methods have been widely employed in the past for the production of pyrazolic chalcones, often relying on traditional chemical processes that may involve the use of hazardous reagents and generate significant waste. On the other hand, green synthesis methods, in harmony with the growing emphasis on sustainable practices in drug discovery, offer a more environmentally friendly alternative. Green synthesis typically involves the use of eco-friendly reagents, solvents, and energy-efficient processes, resulting in reduced environmental impact and improved resource efficiency. Overall, pyrazolic chalcone derivatives represent a promising class of compounds with significant potential for therapeutic applications.

Green synthesis of neuroprotective spirocyclic chalcone derivatives and their role in protecting against traumatic optic nerve injury

For clinically prevalent traumatic optic neuropathy (TON) and other retinal and optic nerve injuries lacking effective therapeutic agents, there is an urgent clinical demand for developing highly efficient and safe neuroprotective agents. Here, we have integrated naturally sourced chalcone with isatin through a catalyst-free green synthesis method, reporting a series of spirocyclic chalcone derivatives with significantly lower cytotoxicity than chalcone itself. Following in vitro cell protection assays in models of hydrogen peroxide and glutamic acid-induced damage, multiple active compounds capable of combating both forms of damage were identified. Among these, candidate compound X38 demonstrated promising neuroprotective prospects: in vitro, it attenuated glutamate-induced cell apoptosis, while in vivo, it effectively ameliorated retinal thinning and loss of optic nerve electrophysiological function induced by optic nerve injury. Preliminary mechanistic studies suggest that X38 exerts its neuroprotective effects by mitigating intracellular ROS accumulation, inhibiting JNK phosphorylation, and alleviating oxidative stress. Additionally, acute toxicity studies (intraperitoneal injection, 500 mg/kg) underscored the favorable in vivo safety profile of X38. Taken together, this study has designed a class of safe, neuroprotective spirocyclic chalcone derivatives that can be synthesized using green methods, offering an attractive candidate for treating retinal and optic nerve injuries.

Computational investigation of naturally occurring anticancer agents in regulating Hedgehog pathway proteins

Embryonic development in humans is controlled by the Hedgehog pathway, which becomes inactive in mature tissues. Except for tissue maintenance and healing, activation of this pathway results in tumorigenesis with only a few exceptions. The drugs currently in use have shown no effectiveness in blocking the key proteins responsible for tumorigenesis. Therefore, it is crucial to find new inhibitors that can stop the abnormal activation of the pathway. A preliminary Insilco screening of naturally occurring compounds was carried out to identify potential inhibitors of the pathway. Docking of seventeen naturally occurring antitumorigenic compounds against the four key proteins of the regulatory proteins of the Hedgehog pathway using AutoDock v4.2.6 software was carried out. Liriodenine exhibited the strongest binding affinity towards three out of the four regulatory proteins (-7.61 kcal/mol with Smoothened, -8.14 kcal/mol with Patched-I, and -6.15 kcal/mol with Gli-II) of the Hedgehog pathway, whereas 2',4-dihydroxy-3-methoxychalcone displayed the highest binding affinity of -7.04 kcal/mol with the Sonic Hedgehog protein. Additional molecular dynamic simulation was conducted using Gromacs with Liriodenine and 2',4-dihydroxy-3-methoxy chalcone. Every protein-ligand complex underwent simulation using v5.1.4 software for a duration of 100 nanoseconds. The findings from the simulation indicate that Liriodenine and 2',4-dihydroxy-3-methoxy chalcone form a strong bond with their corresponding protein. Our findings show that the two aforementioned molecules have potential as new inhibitors of the pathway and should be further investigated in both invitro and in vivo experiments.

Recent Progress in Terrestrial Biota Derived Antibacterial Agents for Medical Applications

Conventional antibiotic and multidrug treatments are becoming less and less effective and the discovery of new effective and safe antibacterial agents is becoming a global priority. Returning to a natural antibacterial product is a relatively new current trend. Terrestrial biota is a rich source of biologically active substances whose antibacterial potential has not been fully utilized. The aim of this review is to present the current state-of-the-art terrestrial biota-derived antibacterial agents inspired by natural treatments. It summarizes the most important sources and newly identified or modified antibacterial agents and treatments from the last five years. It focuses on the significance of plant- animal- and bacteria-derived biologically active agents as powerful alternatives to antibiotics, as well as the advantages of utilizing natural antibacterial molecules alone or in combination with antibiotics. The main conclusion is that terrestrial biota-derived antibacterial products and substances open a variety of new ways for modern improved therapeutic strategies. New terrestrial sources of known antibacterial agents and new antibacterial agents from terrestrial biota were discovered during the last 5 years, which are under investigation together with some long-ago known but now experiencing their renaissance for the development of new medical treatments. The use of natural antibacterial peptides as well as combinational therapy by commercial antibiotics and natural products is outlined as the most promising method for treating bacterial infections. In vivo testing and clinical trials are necessary to reach clinical application.

Synthesis and antibacterial activities of heterocyclic ring-fused 20(S)-protopanaxadiol derivatives

Multidrug-resistant (MDR) bacterial infections are becoming a life-threatening issue in public health; therefore, it is urgent to develop novel antibacterial agents for treating infections caused by MDR bacteria. The 20(S)-protopanaxadiol (PPD) derivative 9 was identified as a novel antibacterial hit compound in screening of our small synthetic natural product-like (NPL) library. A series of novel PPD derivatives with heterocyclic rings fused at the C-2 and C-3 positions of the A-ring were synthesized and their antibacterial activities against Staphylococcus aureus (S. aureus) Newman strain and MDR S. aureus strains (USA300, NRS-1, NRS-70, NRS-100, NRS-108, NRS-271, XJ017, and XJ036) were evaluated. Among these compounds, quinoxaline derivative 56 (SH617) exhibited the highest activity with MICs of 0.5-4 μg/mL against the S. aureus Newman strain and the eight MDR S. aureus strains. Its antibacterial activity was comparable to that of the positive control, vancomycin. In the zebrafish, 56 revealed no obvious toxicity even at a high administered dose. In vivo, following a lethal infection induced by USA300 strains in zebrafish, 56 exhibited significantly increased survival rates in a dose-dependent manner.

Synthesis and In vitro evaluation of bichalcones as novel anti-toxoplasma agents

Toxoplasmosis is a zoonotic disease caused by Toxoplasma gondii, an apicomplexan parasite that infects approximately a third of the world's human population. This disease can cause serious complications during pregnancy and can be fatal in immunocompromised hosts. The current treatment options for toxoplasmosis face several limitations. Thus, to address the urgent medical need for the discovery of novel anti-toxoplasma potential drug candidates, our research focused on exploring a series of monomeric and dimeric chalcones, polyphenolic molecules belonging to the class of flavonoids. Chalcones 1aa-1bg and axially chiral A-A'-connected bichalcones 2aa-2bg were evaluated in vitro against the proliferation of the parasite in a cell-based assay. A comparison of the efficacy demonstrated that, in several cases, bichalcones exhibited increased bioactivity compared to their corresponding monomeric counterparts. Among these compounds, a bichalcone with a phenyl substituent and a methyl moiety 2ab showed the most potent and selective inhibitory activity in the nanomolar range. Both enantiomers of this bichalcone were synthesized using an axially chiral biphenol building block. The biaryl bond was forged using Suzuki cross-coupling in water under micellar catalysis conditions. Separation of the atropisomers of this biphenol building block was conducted by chiral HPLC on a preparative scale. The biological evaluation of the enantiomers revealed that the (R a)-enantiomer (R a)-2ab is the eutomer. These studies suggest that bichalcones may be important drug candidates for further in vivo evaluations for the discovery of anti-toxoplasma drugs.

Design, synthesis and biological evaluation of novel pyrazole-based compounds as potential chemotherapeutic agents

Aim: Design and synthesis of pyrazole-based chemotherapeutic agents. Materials & methods: A series of novel diphenyl pyrazole-chalcone derivatives were synthesized and assessed for their cytotoxic activities against 14 cancer cell lines and their antimicrobial activities against MRSA and Escherichia coli along with their safety using HSF normal cell line. Results & conclusion: Majority of the compounds showed moderate-to-significant anticancer activity with selective high percentage inhibition (>80%) against HNO-97 while being nontoxic toward normal cells. Compounds 6b and 6d were the most potent congeners with IC50 of 10 and 10.56 μM respectively. The synthesized compounds exhibited moderate to potent antimicrobial activities. Interestingly, compound 6d exhibited a minimum inhibitory concentration of 15.7 μg/ml against MRSA; and a minimum inhibitory concentration of 7.8 μg/ml versus E. coli.

Discovery of Loureirin analogues with colorectal cancer suppressive activity via regulating cell cycle and Fas death receptor

Chalcones and dihydrochalcones (DHCs) are important bioactive natural products (BNPs) isolated from traditional Chinese medicine. In this study, 13 chalcones were designed with the inspiration of Loureirin, a DHC extracted from Resina Draconis, and synthesized by classical Claisen-Schmidt reactions. Afterwards the reduction reactions were carried out to obtain the corresponding DHCs. Cytotoxicity assay indicated chalcones and DHCs possessed selective cytotoxicity against colorectal cancer (CRC) cells. The preliminary structure-activity relationships (SAR) of these compounds suggested the α, β-unsaturated ketone of the chalcones were crucial for the anticancer activity. Interestingly, compounds 3d and 4c exhibited selective anticancer activity against CRC cell line HCT116 with IC50s of 8.4 and 17.9 μM but not normal cell. Moreover, 4c could also inhibit the migration and invasion of CRC cells. Mechanism investigations showed 4c could induce cell cycle G2/M arrest by regulating cell cycle-associated proteins and could also up-regulate Fas cell surface death receptor. The virtual docking further pointed out that compounds 3d and 4c could nicely bind to the Fas/FADD death domain complex (ID: 3EZQ). Furthermore, silencing of Fas significantly enhanced the proliferation of CRC cells and attenuated the cytotoxicity induced by 4c. These results suggested 4c exerted its anticancer activity possibly regulating cell cycle and Fas death receptor. In summary, this study investigated the anticancer activity and mechanism of Loureirin analogues in CRC, suggesting these compounds may warrant further investigation as promising anticancer drug candidates for the treatment of CRC.

Synthesis of Novel Triazine-Based Chalcones and 8,9-dihydro-7H-pyrimido[4,5-b][1,4]diazepines as Potential Leads in the Search of Anticancer, Antibacterial and Antifungal Agents

This study presents the synthesis of four series of novel hybrid chalcones (20,21)a-g and (23,24)a-g and six series of 1,3,5-triazine-based pyrimido[4,5-b][1,4]diazepines (28-33)a-g and the evaluation of their anticancer, antibacterial, antifungal, and cytotoxic properties. Chalcones 20b,d, 21a,b,d, 23a,d-g, 24a-g and the pyrimido[4,5-b][1,4]diazepines 29e,g, 30g, 31a,b,e-g, 33a,b,e-g exhibited outstanding anticancer activity against a panel of 60 cancer cell lines with GI50 values between 0.01 and 100 μM and LC50 values in the range of 4.09 μM to >100 μM, several of such derivatives showing higher activity than the standard drug 5-fluorouracil (5-FU). On the other hand, among the synthesized compounds, the best antibacterial properties against N. gonorrhoeae, S. aureus (ATCC 43300), and M. tuberculosis were exhibited by the pyrimido[4,5-b][1,4]diazepines (MICs: 0.25-62.5 µg/mL). The antifungal activity studies showed that triazinylamino-chalcone 29e and triazinyloxy-chalcone 31g were the most active compounds against T. rubrum and T. mentagrophytes and A. fumigatus, respectively (MICs = 62.5 μg/mL). Hemolytic activity studies and in silico toxicity analysis demonstrated that most of the compounds are safe.

Recent Advancement in Bioactive Chalcone Hybrids as Potential Antimicrobial Agents in Medicinal Chemistry

Chalcones are flavonoid-related aromatic ketones and enones generated from plants. The chalcones have a wide range of biological activities, such as anti-tumor, calming, and antimicrobial activities. In the present review, we have focused on the recently published original research articles on chalcones as a unique antibacterial framework in medicinal chemistry. Chalcones are structurally diverse moieties and can be split into simple and hybrid chalcones, with both having core pharmacophore 1,3-diaryl-2-propen-1-one. Chalcones are isolated from natural sources and also synthesized by using various methods. Their structure-activity relationship, mechanisms, and list of patents are also summarized in this paper. This review article outlines the currently published antimicrobial chalcone hybrids and suggests that chalcone derivatives may be potential antimicrobial agents in the future.

Substituent and solvent effects on UV-visible absorption spectra of chalcones derivatives: Experimental and computational studies

The electronic spectra of the title compounds were measured in ethanol and cyclohexane. Three band systems are distinguished in the spectra of which the first and second band systems are attributed to local excitation of PhCH and PhCO rings. The third absorption band is assigned to a charge transfer (CT) band and is associated with the CO-CH=CH moiety. The solvent plays an important role in the absorption spectra and causes the CT band to consist of two electronic transitions. The effect of substituents on the phenyl rings on the charge transfer band of chalcone derivatives was also established in the two solvents. The converged gas-phase geometries of the studied chalcones was optimized using the DFT PBE0 functional with the basis set 6-311++G**. DFT calculations has been performed for an ethanol solution (using TD-PBE0/6-311++G**) level to understand electronic transitions on terms of energies and oscillator strengths to study the substituent effect on the electronic transitions of the chalcone derivatives. To consider the solvation effect of ethanol on the absorptions, the integral equation formalism variant of the polarizable continuum model (IEFPCM) was used. The calculated energies were in good agreement with experiment results. The molecular modelling technique was followed to monitor the effect of substitutions on the HOMO/LUMO energy and total dipole moment. Transitions between natural transition orbitals are also described as part of this study.

Synthetic non-toxic anti-biofilm agents as a strategy in combating bacterial resistance

The tremendous increase in the bacterial resistance to the available antibiotics is a serious problem for the treatment of various infections. Biofilm formation in bacteria significantly contributes to the bacterial survival in host cells, and is considered as an crucial factor, responsible for bacterial resistance. The response of the bacterial cells in the biofilm to antibiotics is completely different from that of the free floating planktonic cells of the same strain. The anti-biofilm agents that could inhibit the biofilm production without affecting the bacterial growth, apply less selective pressure over the bacterial strains than the traditional antibiotics; thus the development of bacterial resistance would be of low incidence. Many attempts have been performed to discover novel agents capable of interfering with the bacterial biofilm life cycle, and several compounds have shown promising activities in suppressing the biofilm production or in dispersing mature existing biofilms. This review describes the different chemical classes that have anti-biofilm effects against different Gram-positive and Gram-negative bacteria without affecting the bacterial growth.

Synthesis, Docking Studies and Evaluation of Chalcones as Anti-Helicobacter pylori and antitumoral Agents

Helicobacter pylori colonizes the gastric epithelium of 50 % of world population and it is the main etiological agent of human chronic gastritis, peptic ulcer, and gastric cancer. In this study, we synthesized and characterized a series of 14 chalcones and evaluated their anti-H. pylori, NO inhibition (in vitro and in silico), and AGS cells cytotoxic effects. Compounds 3b and 3h showed MIC of 8 μg/mL. We observed structure-activity relationships, mainly related to the influence of methoxy substituent at C-2 (3b) and the nitro group at C-4 (3h) in chalcone scaffold. The fourteen chalcones inhibited the NO production in LPS-stimulated macrophages and showed potential for interaction on the active site of the iNOS enzyme. Finally, 3b and 3h showed the highest selectivity to the AGS cell lines. Thus, ours results suggest 3b and 3h as potential candidates for design of new and effective agents against H. pylori and related diseases.

Synthesis, characterization and evaluation of prenylated chalcones ethers as promising antileishmanial compounds

Drug therapy for leishmaniasis remains a major challenge as currently available drugs have limited efficacy, induce serious side-effects and are not accessible to everyone. Thus, the discovery of affordable drugs is urgently needed. Chalcones present a great potential as bioactive agents due to simple structure and functionalization capacity. The antileishmanial activity of different natural and synthetic chalcones have been reported. Here we report the synthesis of twenty-five novel prenylated chalcones that displayed antiparasitic activity in Leishmania mexicana. All the chalcones were evaluated at 5 µg/mL and eleven compounds exhibited a metabolic inhibition close to or exceeding 50%. Compounds 49, 30 and 55 were the three most active with IC50 values < 10 μM. These chalcones also showed the highest selectivity index (SI) values. Interestingly 49 and 55 possessing a substituent at a meta position in the B ring suggests that the substitution pattern influences antileishmanial activity. Additionally, a tridimensional model of fumarate reductase of L. mexicana was obtained by homology modeling. Docking studies suggest that prenylated chalcones could modulate fumarate reductase activity by binding with good affinity to two binding sites that are critical for the target. In conclusion, the novel prenylated chalcones could be considered as promising antileishmanial agents.

Synthesis and antibacterial activity of 2-benzylidene-3-oxobutanamide derivatives against resistant pathogens

Antibiotic resistance evolves naturally through random mutation. Resistance to antimicrobials is an urgent public health crisis that requires coordinated global action. The ESKAPE bacteria (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are primarily responsible for the rise in resistant pathogens. There is an immediate requirement to identify a novel molecular scaffold with potent anti-microbial properties. We developed an efficient one-step synthesis of 2-benzylidene-3-oxobutanamide and its derivatives, which allowed the introduction of an α,β-unsaturated ketone moiety in the quest to identify a new molecular scaffold. Seven compounds exhibited very good antibacterial activity in vitro against WHO priority drug-resistant bacteria such as methicillin resistant Staphyloccus aureus (MRSA) and Acinetobacter baumannii-Multi drug resistant (MDR-AB). In cultured human embryonic kidney cells and hemolysis assays, the potent compounds displayed minimal toxicity. These findings suggest that these small molecules with excellent diversity have the potential to combat antibacterial resistance.

Cryopreservation of bioflavonoid-rich plant sources and bioflavonoid-microcapsules: emerging technologies for preserving bioactivity and enhancing nutraceutical applications

Bioflavonoids are natural polyphenolic secondary metabolites that are medicinal. These compounds possess antitumor, cardioprotective, anti-inflammatory, antimicrobial, antiviral, and anti-psoriasis properties to mention a few. Plant species that contain bioflavonoids should be preserved as such. Also, the bioactivity of the bioflavonoids as neutraceutical compounds is compromised following extraction due to their sensitivity to environmental factors like light, pH, and temperature. In other words, the bioflavonoids' shelf-life is affected. Scientists noticed that bioflavonoids have low solubility properties, poor absorption, and low bioavailability following consumption. Researchers came up with methods to encapsulate bioflavonoids in order to circumvent the challenges above and also to mask the unpleasant order these chemicals may have. Besides, scientists cryopreserve plant species that contain bioflavonoids. In this review, we discuss cryopreservation and bioflavonoid microencapsulation focusing mainly on vitrification, slow freezing, and freeze-drying microencapsulation techniques. In addition, we highlight bioflavonoid extraction techniques, medicinal properties, challenges, and future perspectives of cryopreservation and microencapsulation of bioflavonoids. Regardless of the uniqueness of cryopreservation and microencapsulation as methods to preserve bioflavonoid sources and bioflavonoids' bioactivity, there are challenges reported. Freeze-drying technology is costly. Cryoprotectants damage the integrity of plant cells, to say the least. Researchers are working very hard to overcome these challenges. Encapsulating bioflavonoids via coaxial electrospray and then cryopreserving the micro/nanocapsules produced can be very interesting.

Synthesis and molecular docking of new N4-piperazinyl ciprofloxacin hybrids as antimicrobial DNA gyrase inhibitors

A series of N-4 piperazinyl ciprofloxacin derivatives as urea-tethered ciprofloxacin-chalcone hybrids 2a-j and thioacetyl-linked ciprofloxacin-pyrimidine hybrids 5a-i were synthesized. The target compounds were investigated for their antibacterial activity against S. aureus, P. aeruginosa, E. coli, and C. albicans strains, respectively. Ciprofloxacin derivatives 2a-j and 5a-i revealed broad antibacterial activity against either Gram positive or Gram negative strains, with MIC range of 0.06-42.23 µg/mL compared to ciprofloxacin with an MIC range of 0.15-3.25 µg/mL. Among the tested compounds, hybrids 2b, 2c, 5a, 5b, 5h, and 5i exhibited remarkable antibacterial activity with MIC range of 0.06-1.53 µg/mL against the tested bacterial strains. On the other hand, compounds 2c, 2e, 5c, and 5e showed comparable antifungal activity to ketoconazole against candida albicans with MIC range of 2.03-3.89 µg/mL and 2.6 µg/mL, respectively. Further investigations showed that some ciprofloxacin hybrids have inhibitory activity against DNA gyrase as potential molecular target compared to ciprofloxacin with IC50 range of 0.231 ± 0.01-7.592 ± 0.40 µM and 0.323 ± 0.02 µM, respectively. Docking studies of compounds 2b, 2c, 5b, 5c, 5e, 5h, and 5i on the active site of DNA gyrase (PDB: 2XCT) confirmed their ability to form stable complex with the target enzyme like that of ciprofloxacin.

Synthesis, reactions and application of chalcones: a systematic review

Chalcones are a group of naturally occurring compounds that have biological effects that include anti-inflammatory, anti-cancer, and antibacterial properties. Current chalcone research, including their synthesis, structure-activity relationships, and biological activities, is summarized herein. Along with their toxicity and safety profiles, the prospective usage of chalcones in medicinal research and development is discussed. This review emphasizes the need for additional research in order to fully examine the therapeutic potential of chalcones as therapeutic agents for the treatment of a variety of disorders.

Novel Thiazolylketenyl Quinazolinones as Potential Anti-MRSA Agents and Allosteric Modulator for PBP2a

Bacterial infections caused by methicillin-resistant Staphylococcus aureus have seriously threatened public health. There is an urgent need to propose an existing regimen to overcome multidrug resistance of MRSA. A unique class of novel anti-MRSA thiazolylketenyl quinazolinones (TQs) and their analogs were developed. Some synthesized compounds showed good bacteriostatic potency. Especially TQ 4 was found to exhibit excellent inhibition against MRSA with a low MIC of 0.5 μg/mL, which was 8-fold more effective than norfloxacin. The combination of TQ 4 with cefdinir showed stronger antibacterial potency. Further investigation revealed that TQ 4, with low hemolytic toxicity and low drug resistance, was not only able to inhibit biofilm formation but also could reduce MRSA metabolic activity and showed good drug-likeness. Mechanistic explorations revealed that TQ 4 could cause leakage of proteins by disrupting membrane integrity and block DNA replication by intercalated DNA. Furthermore, the synergistic antibacterial effect with cefdinir might be attributed to TQ 4 with the ability to induce PBP2a allosteric regulation of MRSA and further trigger the opening of the active site to promote the binding of cefdinir to the active site, thus inhibiting the expression of PBP2a, thereby overcoming MRSA resistance and significantly enhancing the anti-MRSA activity of cefdinir. A new strategy provided by these findings was that TQ 4, possessing both excellent anti-MRSA activity and allosteric effect of PBP2a, merited further development as a novel class of antibacterial agents to overcome increasingly severe MRSA infections.

Examining the Scope of Deriving β-Aryl Enones from Enol Silanes as Ketone Equivalents via Pd(II)-Mediated Sequential Dehydrosilylation and Arylation

Silyl enol ethers were examined as a masked source of saturated ketones to derive β-aryl enones and their derivatives by dehydrosilylation to generate enones in situ and subsequent oxidative arylation with arylboronic acids as transmetallation coupling partners using relayed Pd(II) catalysis in one pot under base-free conditions. Oxygen was found to be an efficient and green oxidant to enable both dehydrosilylation of enol silanes and arylation. Additionally, arylation conditions can be custom-designed to take advantage of aryl halides as an alternative source of arylating agents. The preparative scope was investigated with 35 examples (up to 95% yield), and mechanistic studies implied a cationic Pd(II)-based catalytic system.

Synthesis of chalcones and their antimicrobial and drug potentiating activities

The increased resistance of microorganisms to antimicrobial drugs makes it necessary to search for new active compounds, such as chalcones. Their simple chemical structure makes them molecules easy to synthesize. Therefore, the aim of this study was to evaluate the antimicrobial and potentiating activity of antibiotics and antifungals by synthetic chalcones against strains of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Candida tropicalis. The synthesis of chalcones was carried out by Claisen-Schimidt aldol condensation. Nuclear Magnetic Resonance (NMR) and Gas Chromatography Coupled to Mass Spectrometry (GC/MS) were also performed. Microbiological tests were performed by the broth microdilution method, using gentamicin, norfloxacin and penicillin as standard drugs for the antibacterial assay, and fluconazole for the antifungal assay. Three chalcones were obtained (1E,4E)-1,5-diphenylpenta-1,4-dien-3-one (DB-Acetone), (1E,3E,6E,8E)-1,9-diphenylnone-1,3,6,8-tetraen-5-one (DB-CNM), (1E,4E)-1,5-bis (4-methoxyphenyl) penta-1,4-dien-3-one (DB-Anisal). The compound DB-Acetone was able to inhibit P. aeruginosa ATCC 9027 at a concentration of 1.4 × 10² μM (32 μg/mL), while DB-CNM and DB-Anisal inhibited the growth of S. aureus ATCC 25923 at 17.88 × 10² μM and 2.71 × 10¹ μM (512 μg/mL and 8 μg/mL) respectively. In the combined activity, DB-Anisal was able to potentiate the effect of the three antibacterial drugs tested against E. coli 06, norfloxacin (128 for 4 μg/mL ±1) against P. aeruginosa 24 and penicillin (1,024 for 16 μg/mL ±1) against S. aureus 10. In antifungal assays, chalcones were not able to inhibit the growth of fungal strains tested. However, both showed potentiating activity with fluconazole, ranging from 8.17 x 10^-1 μM (0.4909 μg/mL) to 2.35 μM (13.96 μg/mL). It is concluded that synthetic chalcones have antimicrobial potential, demonstrating good intrinsic activity against fungi and bacteria, in addition to potentiating the antibiotics and antifungal tested. Further studies are needed addressing the mechanisms of action responsible for the results found in this work.

Thiocarbohydrazone and Chalcone-Derived 3,4-Dihydropyrimidinethione as Lipid Peroxidation and Soybean Lipoxygenase Inhibitors

The potential of the 4,6-diphenyl-3,4-dihydropyrimidine-2(1H)-thione (abbreviated as KKII5) and (E)-N'-benzylidenehydrazinecarbothiohydrazide (abbreviated as DKI5) compounds as possible drug leads is investigated. KKII5 and DKI5 are synthesized in high yield of up to 97%. Their structure, binding in the active site of the LOX-1 enzyme, and their toxicity are studied via joint experimental and computational methodologies. Specifically, the structure assignment and conformational analysis were achieved by applying homonuclear and heteronuclear 2D nuclear magnetic resonance (NMR) spectroscopy (2D-COSY, 2D-NOESY, 2D-HSQC, and 2D-HMBC) and density functional theory (DFT). The obtained DFT lowest energy conformers were in agreement with the NOE correlations observed in the 2D-NOESY spectra. Additionally, docking and molecular dynamics simulations were performed to discover their ability to bind and remain stabile in the active site of the LOX-1 enzyme. These in silico experiments and DFT calculations indicated favorable binding for the enzyme under study. The strongest binding energy, -9.60 kcal/mol, was observed for dihydropyrimidinethione KKII5 in the active site of LOX-1. ADMET calculations showed that the two molecules lack major toxicities and could serve as possible drug leads. The redox potential of the active center of LOX-1 with the binding molecules was calculated via DFT methodology. The results showed a significantly smaller energy attachment of 2.8 eV with KKII5 binding in comparison to DKI5. Thus, KKII5 enhanced the ability of the active center to receive electrons compared to DKI5. This is related to the stronger binding interaction of KKII5 relative to that of DK15 to LOX-1. The two very potent LOX-1 inhibitors exerted IC₅₀ 19 μΜ (KKII5) and 22.5 μΜ (DKI5). Furthermore, they both strongly inhibit lipid peroxidation, namely, 98% for KKII5 and 94% for DKI5.

Chalcone: A potential scaffold for NLRP3 inflammasome inhibitors

Overactivated NLRP3 inflammasome has been shown to associate with an increasing number of disease conditions. Activation of the NLRP3 inflammasome results in caspase-1-catalyzed formation of active pro-inflammatory cytokines (IL-1β and IL-18) resulting in pyroptosis. The multi-protein composition of the NLRP3 inflammasome and its sensitivity to several damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs) make this extensively studied inflammasome an attractive target to treat chronic conditions. However, none of the known NLRP3 inhibitors has been approved for clinical use. Sulfonylurea and covalent inhibitors with electrophilic warhead (Michael acceptor) are among the prominent classes of compounds explored for their NLRP3 inhibitory effects. Chalcone, a small molecule with α, β unsaturated carbonyl group (Michael acceptor), has also been studied as a promising scaffold for the development of NLRP3 inhibitors. Low molecular weight, easy to manipulate lipophilicity and cost-effectiveness have attracted many to use chalcone scaffold for drug development. In this review, we highlight chalcone derivatives with NLRP3 inflammasome inhibitory activities. Recent developments and potential new directions summarized here will, hopefully, serve as valuable perspectives for investigators including medicinal chemists and drug discovery researchers to utilize chalcone as a scaffold for developing novel NLRP3 inflammasome inhibitors.

Exploring biogenic chalcones as DprE1 inhibitors for antitubercular activity via in silico approach

Cases of drug-resistant tuberculosis (TB) have increased worldwide in the last few years, and it is a major threat to global TB control strategies and the human population. Mycobacterium tuberculosis is a common causative agent responsible for increasing cases of TB and as reported by WHO, approximately, 1.5 million death occurred from TB in 2020. Identification of new therapies against drug-resistant TB is an urgent need to be considered primarily. The current investigation aims to find the potential biogenic chalcone against the potential targets of drug-resistant TB via in silico approach. The ligand library of biogenic chalcones was screened against DprE1. Results of molecular docking and in silico ADMET prediction revealed that ZINC000005158606 has lead-like properties against the targeted protein. Pharmacophore modeling was done to identify the pharmacophoric features and their geometric distance present in ZINC000005158606. The binding stability study performed using molecular dynamics (MD) simulation of the DprE1-ZINC000005158606 complex revealed the conformational stability of the complex system over 100 ns with minimum deviation. Further, the in silico anti-TB sensitivity of ZINC000005158606 was found to be higher as compared to the standards against Mycobacterium tuberculosis. The overall in silico investigation indicated the potential of identified hit to act as a lead molecule against Mycobacterium tuberculosis.

Geranylation of Chalcones by a Fungal Aromatic Prenyltransferase

Geranylated chalcones mainly exist in plants, and many of them have attracted attention because of their diverse pharmacological and biological activities. Herein, we report geranylation of eight chalcones by the Aspergillus terreus aromatic prenyltransferase AtaPT. Ten new mono-geranylated enzyme products (1G-5G, 6G1, 6G2, 7G, 8G1, and 8G2) were obtained. Most of the products are C-geranylated products with prenyl moieties at ring B. In comparison, plant aromatic prenyltransferases usually catalyze the geranylation at ring A. Therefore, AtaPT can be used complementarily for chalcone geranylation to increase the structural diversity of small molecules. In addition, seven compounds (1G, 3G, 4G, 6G1, 7G, 8G1, and 8G2) exhibited a potential inhibitory effect on α-glucosidase with the IC₅₀ values ranging from 45.59 ± 3.48 to 82.85 ± 2.15 μg/mL. Among them, compound 7G (45.59 ± 3.48 μg/mL) was the most potential α-glucosidase inhibitor, which is about seven times stronger than the positive control acarbose (IC₅₀ = 346.63 ± 15.65 μg/mL).

Antifungal evaluation of quinoline-chalcone derivatives combined with FLC against drug-resistant Candida albicans

With the widespread clinical use of FLC, the FLC-resistant C. albicans greatly increases the difficulty of treatment, and drug combination becomes an important method to treat C. albicans infection. In this work, we have prepared a series of quinoline-chalcone derivatives in good yields, and in vitro antifungal activity against C. albicans were evaluated. The results indicated that most title compounds combined with FLC showed good antifungal activity against drug-resistant C. albicans. Further mechanism researches demonstrated that 6a and 6c combined with FLC could significantly inhibited growth and biofilm formation of C. albicans, induce ROS accumulation, impair the mitochondrial membrane, and decrease intracellular ATP concentrations.

Discovery of N-Phenylpropiolamide as a Novel Succinate Dehydrogenase Inhibitor Scaffold with Broad-Spectrum Antifungal Activity on Phytopathogenic Fungi

Based on the structural features of both succinate dehydrogenase inhibitors (SDHIs) and targeted covalent inhibitors, a series of N-phenylpropiolamides containing a Michael acceptor moiety were designed to find new antifungal compounds. Nineteen compounds showed potent inhibition activity in vitro on nine species of plant pathogenic fungi. Compounds 9 and 13 showed higher activity on most of the fungi than the standard drug azoxystrobin. Compound 13 could completely inhibit Physalospora piricola infection on apples at 200 μg/mL concentration over 7 days and showed high safety to seed germination and seedling growth of plants at ≤100 μg/mL concentration. The action mechanism showed that 13 is an SDH inhibitor with a median inhibitory concentration, IC₅₀, value of 0.55 μg/mL, comparable with that of the positive drug boscalid. Molecular docking studies revealed that 13 can bind well to the ubiquinone-binding region of SDH by hydrogen bonds and undergoes π-alkyl interaction and π-cation interaction. At the cellular level, 1 as the parent compound could destruct the mycelial structure of P. piricola and partly dissolve the cell wall and/or membrane. Structure-activity relationship analysis showed that the acetenyl group should be a structure determinant for the activity, and the substitution pattern of the phenyl ring can significantly impact the activity. Thus, N-phenylpropiolamide emerged as a novel and promising lead scaffold for the development of new SDHIs for plant protection.

Benzenesulfonyl thiazoloimines as unique multitargeting antibacterial agents towards Enterococcus faecalis

New efficient antimicrobial agents are urgently needed to combat invasive multidrug-resistant pathogens infections. Structurally unique benzenesulfonyl thiazoloimines (BSTIs) were exploited as novel potential antibacterial victors to confront terrific drug resistance. Some developed BSTIs exerted effectively antimicrobial efficacy against the tested strains. Notably, 2-pyridyl BSTI 14d exhibited good antibacterial activity against E. faecalis with MIC value of 1 μg/mL, which was superior to sulfathiazole and norfloxacin. The most active compound 14d not only showed rapid bactericidal properties and impeded E. faecalis biofilm formation to effectually relieve the development of drug resistance, but also performed low toxicity toward human red blood cells, human normal squamous epithelial cells and human non-neoplastic colon epithelial cells. Mechanistic investigation demonstrated that molecule 14d could exert efficient membrane destruction leading to the leakage of intracellular materials and metabolism inhibition, cause oxidative damage of E. faecalis through accumulation of excess reactive oxygen species and reduction of glutathione activity, and intercalate into DNA to hinder replication of DNA. Molecular docking indicated that the formation of 14d-dihydrofolate synthetase supramolecular complex could hinder the function of this enzyme. ADME analysis displayed that compound 14d possessed promising pharmacokinetic properties. These findings suggested that the newly developed benzenesulfonyl thiazoloimines with multitargeting antibacterial potential provided a new possibility for evading resistance.

In silico studies, X-ray diffraction analysis and biological investigation of fluorinated pyrrolylated-chalcones in zebrafish epilepsy models

Epilepsy is the third most common known brain disease worldwide. Several antiepileptic drugs (AEDs) are available to improve seizure control. However, the associated side effects limit their practical use and highlight the ongoing search for safer and effective AEDs. Eighteen newly designed fluorine-containing pyrrolylated chalcones were extensively studied in silico, synthesized, structurally analyzed by X-ray diffraction (XRD), and biologically and toxicologically tested as potential new AEDs in zebrafish epilepsy in vivo models. The results predicted that 3-(3,5-difluorophenyl)-1-(1H-pyrrol-2-yl)prop-2-en-1-one (compound 8) had a good drug-like profile with binding affinity to γ-aminobutyric acid receptor type-A (GABA_A, -8.0 kcal/mol). This predicted active compound 8 was effective in reducing convulsive behaviour in pentylenetetrazol (PTZ)-induced larvae and hyperactive movements in zc4h2 knockout (KO) zebrafish, experimentally. Moreover, no cardiotoxic effect of compound 8 was observed in zebrafish. Overall, pyrrolylated chalcones could serve as alternative AEDs and warrant further in-depth pharmacological studies to uncover their mechanism of action.

Flavonoid Production: Current Trends in Plant Metabolic Engineering and De Novo Microbial Production

Flavonoids are secondary metabolites that represent a heterogeneous family of plant polyphenolic compounds. Recent research has determined that the health benefits of fruits and vegetables, as well as the therapeutic potential of medicinal plants, are based on the presence of various bioactive natural products, including a high proportion of flavonoids. With current trends in plant metabolite research, flavonoids have become the center of attention due to their significant bioactivity associated with anti-cancer, antioxidant, anti-inflammatory, and anti-microbial activities. However, the use of traditional approaches, widely associated with the production of flavonoids, including plant extraction and chemical synthesis, has not been able to establish a scalable route for large-scale production on an industrial level. The renovation of biosynthetic pathways in plants and industrially significant microbes using advanced genetic engineering tools offers substantial promise for the exploration and scalable production of flavonoids. Recently, the co-culture engineering approach has emerged to prevail over the constraints and limitations of the conventional monoculture approach by harnessing the power of two or more strains of engineered microbes to reconstruct the target biosynthetic pathway. In this review, current perspectives on the biosynthesis and metabolic engineering of flavonoids in plants have been summarized. Special emphasis is placed on the most recent developments in the microbial production of major classes of flavonoids. Finally, we describe the recent achievements in genetic engineering for the combinatorial biosynthesis of flavonoids by reconstructing synthesis pathways in microorganisms via a co-culture strategy to obtain high amounts of specific bioactive compounds.

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.

Discovery of new cyanopyridine/chalcone hybrids as dual inhibitors of EGFR/BRAF V600E with promising antiproliferative properties

As dual EGFR and BRAF^V600E inhibitors, 2-(3-cyano-4,6-bis(aryl)-2-oxo-1,2-dihydropyridine-1-yl)-N-(4-cinnamoylphenyl) acetamide derivatives 8-20 were developed. Compounds 8, 12, and 13 showed strong antiproliferative activity when the target compounds were synthesized and tested in vitro against four cancer cell lines. These hybrids have a dual inhibition activity on EGFR and BRAF^V600E , according to in vitro studies. The EGFR was inhibited by compounds 8, 12, and 13 with IC₅₀ values between 89 and 110 nM, which were equivalent to those of erlotinib (IC₅₀  = 80 nm). Compound 13 was found to be an effective inhibitor of the proliferation of cancer cells (GI₅₀  = 0.72 µM) and demonstrated hopeful inhibitory activity of BRAF^V600E (IC₅₀  = 58 nm), which is superior to erlotinib (IC₅₀  = 65 nm). Compound 13 caused apoptosis and showed cell cycle arrest in the G0/G1phase in a study on the MCF-7 cell line. The new compounds can fit tightly into the active sites of EGFR and BRAF^V600E kinases, according to molecular docking analyses.

Insights into chalcone analogues with potential as antioxidant additives in diesel-biodiesel blends

Biodiesel production is one of the promising strategies to reduce diesel consumption and an important contribution to climate change. However, biodiesel stability remains a challenging problem in biofuel use in the global energy matrix. In this context, organic additives have been investigated to minimize these problems and reduce harmful emissions to comply with fuel requirement standards. In this study, we discuss a comprehensive structural description, a behavior of B15 [85% volume of diesel and 15% volume of biodiesel (B100)] stability in the presence of antioxidants (chalcone analogues), and a theoretical calculation to pave the way for clarifying and expanding the potential of title compounds as an antioxidant additive for diesel-biodiesel blends. Finally, a systematic description of the oxidation stability was undertaken using a specialized machine learning computational pySIRC platform.

Pharmacotherapeutics Applications and Chemistry of Chalcone Derivatives

Chalcones have been well examined in the extant literature and demonstrated antibacterial, antifungal, anti-inflammatory, and anticancer properties. A detailed evaluation of the purported health benefits of chalcone and its derivatives, including molecular mechanisms of pharmacological activities, can be further explored. Therefore, this review aimed to describe the main characteristics of chalcone and its derivatives, including their method synthesis and pharmacotherapeutics applications with molecular mechanisms. The presence of the reactive α,β-unsaturated system in the chalcone's rings showed different potential pharmacological properties, including inhibitory activity on enzymes, anticancer, anti-inflammatory, antibacterial, antifungal, antimalarial, antiprotozoal, and anti-filarial activity. Changing the structure by adding substituent groups to the aromatic ring can increase potency, reduce toxicity, and broaden pharmacological action. This report also summarized the potential health benefits of chalcone derivatives, particularly antimicrobial activity. We found that several chalcone compounds can inhibit diverse targets of antibiotic-resistance development pathways; therefore, they overcome resistance, and bacteria become susceptible to antibacterial compounds. A few chalcone compounds were more active than conventional antibiotics, like vancomycin and tetracycline. On another note, a series of pyran-fused chalcones and trichalcones can block the NF-B signaling complement system implicated in inflammation, and several compounds demonstrated more potent lipoxygenase inhibition than NSAIDs, such as indomethacin. This report integrated discussion from the domains of medicinal chemistry, organic synthesis, and diverse pharmacological applications, particularly for the development of new anti-infective agents that could be a useful reference for pharmaceutical scientists.

Antibacterial quaternary ammonium agents: Chemical diversity and biological mechanism

Bacterial infections have seriously threatened public health especially with the increasing resistance and the cliff-like decline of the number of newly approved antibacterial agents. Quaternary ammonium compounds (QACs) possess potent medicinal properties with 95 successfully marketed drugs, which also have a long history as antibacterial agents. In this review, we summarize the chemical diversity of antibacterial QACs, divided into chain-like and aromatic ring, reported over the past decade (2012 to mid-2022). Additionally, the structure-activity relationships, mainly covering hydrophobicity, charges and skeleton features, are discussed. In the cases where sufficient information is available, antibacterial mechanisms including biofilm, cell membrane, and intracellular targets are presented. It is hoped that this review will provide sufficient information for medicinal chemists to discover the new generation of antibacterial agents based on QACs.

Comprehensive insight into anti-staphylococcal and anti-enterococcal action of brominated and chlorinated pyrazine-based chalcones

The greatest threat and medicinal impact within gram-positive pathogens are posed by two bacterial genera, Staphylococcus and Enterococcus. Chalcones have a wide range of biological activities and are recognized as effective templates in medicinal chemistry. This study provides comprehensive insight into the anti-staphylococcal and anti-enterococcal activities of two recently published brominated and chlorinated pyrazine-based chalcones, CH-0y and CH-0w. Their effects against 4 reference and 12 staphylococcal and enterococcal clinical isolates were evaluated. Bactericidal action, the activity in combination with selected conventional antibiotics, the study of post-antimicrobial effect (PAE, PAE/SME), and in vitro and in vivo toxicity, were included. In CH-0y, anti-staphylococcal activity ranging from MIC = 15.625 to 62.5 μM, and activity against E. faecium from 31.25 to 62.5 μM was determined. In CH-0w, anti-staphylococcal activity ranging from 31.25 to 125 μM, and activity against E. faecium and E. faecalis (62.5 μM) was revealed. Both CH-0y and CH-0w showed bactericidal action, beneficial impact on bacterial growth delay within PAE and PAE/SME studies, and non/low toxicity in vivo. Compared to CH-0w, CH-0y seems to have higher anti-staphylococcal and less toxic potential. In conclusion, chalcones CH-0y and CH-0w could be considered as structural pattern for future adjuvants to selected antibiotic drugs.

<p class="CB-Manuscripttitle"><span lang="EN-US">Synthesis, Biological Activity and Molecular Docking Studies of Heterocyclic Chalcones<o:p></o:p></span></p>

Nineteen heterocyclic chalcones were synthesized from 4-acetyl-5-methylquinolylpyrazole and heteroaryl (imidazole, pyrazole, thiophene, indole and triazole) aldehydes and screened in vitro using four tumor cell lines for their anticancer capability and for antimicrobial activity. The chalcone 5b exhibited the highest activity with IC 50 values 2.14 μM against colon (HCT-116) and 5.0 μM, against prostate (PC-3) cancer cell lines and also displayed good activity against fungal strain ( A. Niger) with MIC value 9.1 μM . The chalcones 5q and 5p displayed good activity against Gram-positive bacterial strains ( S. aureus ) with MIC value 2.6 µM and fungal strain ( C. Albicans ) with MIC value 5.4 µM, respectively. Molecular docking studies revealed that the synthesized heterocyclic chalcones exhibited hydrogen bond, electrostatic and hydrophobic interactions with their respective biochemical targets.

Chalcone 9X Contributed to Repressing Glioma Cell Growth and Migration and Inducing Cell Apoptosis by Reducing FOXM1 Expression In Vitro and Repressing Tumor Growth In Vivo

Objective. Natural and synthetic chalcones played roles in inflammation and cancers. Chalcone 9X was an aromatic ketone that was found to inhibit cell growth of hepatic cancer and lung cancer cells. In this study, we wanted to investigate the functions of Chalcone 9X in glioma. Materials and Methods. Chemical Chalcone 9X was added in human glioma cell lines (U87 and T98G cells) and normal astrocyte cell lines (HA1800) with various concentrations (0 μmol/L, 20 μmol/L, 50 μmol/L, and 100 μmol/L). CCK-8 assay was used to measure cell viability. Flow cytometric assay was used to measure cell apoptotic rates. Wound healing assay and transwell assay were used to measure cell invasion. RT-PCR was used to detect relative mRNA expressions, and the protein expressions were detected by western blot (WB) and immunohistochemical staining (IHC). Finally, nude mouse xenograft assay was performed to prove the effects of Chalcone 9X in vivo. Results. Results revealed that Chalcone 9X treatment suppressed cell viability and cell migration capacity; it could also induce cell apoptosis in U87 and T98G cells with dose dependence. However, it had little cytotoxicity to normal astrocyte HA1800 cells. Moreover, Chalcone 9X treatment could repress the mRNA and protein expressions of FOXM1 in human glioma cell lines, which was an oncogene that could promote the progression and malignancy of glioma. In addition, FOXM1 overexpression dismissed the Chalcone 9X effects on cell proliferation, apoptosis, and migration in human glioma cell lines. Finally, in vivo assay showed that Chalcone 9X treatment repressed the expression of FOXM1, which inhibited the tumor growth of a xenograft model injected with U87 in nude mice. Conclusions. In all, we found that Chalcone 9X could suppress cell proliferation and migration and induce cell apoptosis in human glioma cells, while it has little cytotoxicity to normal astrocyte cells. Therefore, we uncovered a novel way that Chalcone 9X could inhibit FOXM1 expression and repress the progression and biofunctions of glioma cells, which might be a potential therapeutic drug for treating human glioma.