Recent developments in biological activities of chalcones: a mini review

Crystal structure of (E)-1-(2–nitrophenyl)-3-phenylprop-2-en-1-one, C15H11NO3

C15H11NO3, P21/c (no. 14), a = 5.4092(2) Å, b = 23.9605(8) Å, c = 9.4887(3) Å, β = 96.080(1)°, V = 1222.89(7) Å3, Z = 4, R gt(F) = 0.0358, wR ref(F 2) = 0.0888, T = 173(2) K.

Novel Galactosyl Moiety-Conjugated Furylchalcones Synthesized Facilely Display Significant Regulatory Effect on Plant Growth

The expansion of weed infestation has increased the demand on new herbicides. A series of novel galactosyl moiety-conjugated furylchalcones was facilely synthesized in which the furyl group (A ring) was combined with the substituted benzene group (B ring), and a galactosyl moiety was introduced. All these galactosyl furylchalcones were predicted to be phloem-mobile. Most of the galactosyl furylchalcones significantly promoted early seedling growth of sorghum and barnyardgrass under dark conditions, but all of them revealed considerable anti-growth ability on illuminated pot plants; especially, 1-(3'-(4″-O-β-d-galactopyranosyl)furyl)-3-(4″-nitrophenyl)-2-en-1-one (B₁₁) had a better herbicidal activity against rapeseed and Chinese amaranth than haloxyfop-R-methyl. The median efficient concentrations (EC₅₀) of compound B₁₁ against cucumber and wheat were 9.55 and 26.97 mg/L, respectively, also showing a stronger suppressing capacity than 2,4-D. Molecular docking with phosphoenolpyruvate carboxylase protein showed a stable binding conformation in which the galactosyl group interacted with LYS363 and GLU369, the furan ring and carbonyl bound with ARG184, and the crosslink of the nitro group with GLU240 formed a salt bridge. The results demonstrate that galactosyl furylchalcones possess the great potential as new herbicides for weed management, and further evaluations on more weeds are required for practical application.

The Medicinal Chemistry of Chalcones as Anti-Mycobacterium tuberculosis Agents

Abstract:

Tuberculosis (TB), a highly fatal infectious disease, is caused by Mycobacterium tuberculosis (Mtb) that has inflicted mankind for several centuries. In 2019, the staggering number of new cases reached 10 million resulting in 1.2 million deaths. The emergence of multidrug-resistance-Mycobacterium tuberculosis (MDR-TB) and extensively drug-resistant-Mycobacterium tuberculosis (XDR-TB) is a global concern that requires the search for novel, effective, and safer short-term therapies. Nowadays, among the few alternatives available to treat resistant-Mtb strains, the majority have limitations, which include drug-drug interactions, long-term treatment, and chronic induced toxicities. Therefore, it is mandatory to develop new anti-Mtb agents to achieve health policy goals to mitigate the disease by 2035. Among the several bioactive anti-Mtb compounds, chalcones have been described as the privileged scaffold useful for drug design. Overall, this review explores and analyzes 37 chalcones that exhibited anti-Mtb activity described in the literature up to April 2021 with minimum inhibitory concentration (MIC90) values inferior to 20 µM and selective index superior to 10. In addition, the correlation of some properties for most active compounds was evaluated, and the main targets for these compounds were discussed.

Antioxidant, antimicrobial, and molecular docking studies of novel chalcones and Schiff bases bearing 1, 4-naphthoquinone moiety

Background:

The 1,4-naphthoquinone ring has attracted prominent interest in the field of medicinal chemistry due to its potent pharmacological activity as antioxidant, antibacterial, antifungal, and anticancer.

Objective:

Herein, a series of new Schiff bases (4-6) and chalcones (8a-c & 9a-d) bearing 1,4-naphthoquinone moiety were synthesized in good yields and were subjected to in-vitro antimicrobial, antioxidant, and molecular docking testing.

Methods:

A facile protocol has been described in this study for the synthesis of new derivatives (4-7, 8a-c, and 9a-d) bearing 1,4-naphthoquinone moiety. The chemical structures of all the synthesized compounds were identified by 1H-NMR, 13C-NMR, MS, and elemental analyses. Moreover, these derivatives were assessed for their in-vitro antimicrobial activity against gram-positive, gram-negative bacteria, and fungal strains. Further studies were conducted to test their antioxidant activity using DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging assay. Molecular docking studies were realized to identify the most likely interactions of the novel compounds within the protein receptor.

Results:

The antimicrobial results showed that most of the compounds displayed good efficacy against both bacterial and fungal strains. The antioxidant study revealed that compounds 9d, 9a, 9b, 8c, and 6 exhibited the highest radical scavenging activity. Docking studies of the most active antimicrobial compounds within GLN- 6-P, recorded good scores with several binding interactions with the active sites.

Conclusion:

Based on the obtained results, it was found that compounds 8b, 9b, and 9c displayed the highest activity against both bacterial and fungal strains. The obtained findings from the DPPH radical scavenging method revealed that compounds 9d and 9a exhibited the strongest scavenging potential. The molecular docking studies proved that the most active antimicrobial compounds 8b, 9b and 9c displayed the highest energy binding scores within the glucosamine-6-phosphate synthase (GlcN-6-P) active site.

Soybean isoflavones protect SH-SY5Y neurons from atrazine-induced toxicity by activating mitophagy through stimulation of the BEX2/BNIP3/NIX pathway

Atrazine (ATR) is a widely used herbicide that can induce the degeneration of dopaminergic (DAergic) neurons in the substantia nigra, resulting in a Parkinson's disease-like syndrome. Despite the high risk of environmental exposure, few studies have investigated strategies for the prevention of ATR neurotoxicity. Our previous studies demonstrated that ATR can impair mitochondrial function, leading to metabolic failure. Cells maintain mitochondrial quality through selective autophagic elimination, termed mitophagy. Soybean isoflavones (SI) possess multiple beneficial bioactivities, including preservation of mitochondria function, so it was hypothesized that SI can protect neurons against ATR toxicity by promoting mitophagy. Pretreatment of SH-SY5Y neurons with SI prevented ATR-induced metabolic failure and cytotoxicity as assessed by intracellular ATP, Na+-K+-ATPase activity, mitochondrial membrane potential, and cell viability assays. The neuroprotective efficacy of SI was superior to the major individual components genistein, daidzein, and glycitein. Ultrastructural analyses revealed that ATR induced mitochondrial damage, while SI promoted the sequestration of damaged mitochondria into autophagic vesicles. Soybean isoflavones also induced mitophagy as evidenced by upregulated expression of BNIP3/NIX, BEX2, and LC3-II, while co-treatment with the mitophagy inhibitor Mdivi-1 blocked SI-mediated neuroprotection and prevented SI from reversing ATR-induced BEX2 downregulation. Furthermore, BEX2 knockdown inhibited SI-induced activation of the BNIP3/NIX pathway, mitophagy, and neuroprotection. These findings suggest that SI protects against ATR-induced mitochondrial dysfunction and neurotoxicity by activating the BEX2/BNIP3/NIX pathway.

From natural products to HDAC inhibitors: An overview of drug discovery and design strategy

Histone deacetylases (HDACs) play a key role in the homeostasis of protein acetylation in histones and have recently emerged as a therapeutic target for numerous diseases. The inhibition of HDACs may block angiogenesis, arrest cell growth, and lead to differentiation and apoptosis in tumour cells. Thus, HDAC inhibitors (HDACi) have received increasing attention and many of which are developed from natural sources. In the past few decades, naturally occurring HDACi have been identified to have potent anticancer activities, some of which have demonstrated promising therapeutic effects on haematological malignancies. In this review, we summarized the discovery and modification of HDAC inhibitors from natural sources, novel drug design that uses natural products as parent nuclei, and dual target design strategies that combine HDAC with non-HDAC targets.

Angiogenesis, Anti-Tumor, and Anti-Metastatic Activity of Novel α-Substituted Hetero-Aromatic Chalcone Hybrids as Inhibitors of Microtubule Polymerization

A library of new heteroaromatic ring-linked chalcone analogs were designed and synthesized of these, compound 7m with α-CH₃ substitution and bearing a benzofuran ring, displaying the most potent activity, with IC₅₀ values of 0.07–0.183 µM against three cancer cells. Its low cytotoxicity toward normal human cells and strong potency on drug-resistant cells revealed the possibility for cancer therapy. It also could moderately inhibit in vitro tubulin polymerization with an IC₅₀ value of 12.23 µM, and the disruption of cellular architecture in MCF-7 cells was observed by an immunofluorescence assay. Cellular-based mechanism studies elucidated that 7m arrested the cell cycle at the G2/M phase and induced apoptosis by regulating the expression levels of caspases and PARP protein. Importantly, the compound 7 m was found to inhibit HUVEC tube formation, migration, and invasion in vitro. In vivo assay showed that 7m could effectively destroy angiogenesis of zebrafish embryos. Furthermore, our data suggested that treatment with 7m significantly reduced MCF-7 cell metastasis and proliferation in vitro and in zebrafish xenograft. Collectively, this work showed that chalcone hybrid 7m deserves further investigation as dual potential tubulin polymerization and angiogenesis inhibitor.

Molecular hybrids: A five-year survey on structures of multiple targeted hybrids of protein kinase inhibitors for cancer therapy

Protein kinases have grown over the past few years as a crucial target for different cancer types. With the multifactorial nature of cancer, and the fast development of drug resistance for conventional chemotherapeutics, a strategy for designing multi-target agents was suggested to potentially increase drug efficacy, minimize side effects and retain the proper pharmacokinetic properties. Kinase inhibitors were used extensively in such strategy. Different kinase inhibitor agents which target EGFR, VEGFR, c-Met, CDK, PDK and other targets were merged into hybrids with conventional chemotherapeutics such as tubulin polymerization and topoisomerase inhibitors. Other hybrids were designed gathering kinase inhibitors with targeted cancer therapy such as HDAC, PARP, HSP 90 inhibitors. Nitric oxide donor molecules were also merged with kinase inhibitors for cancer therapy. The current review presents the hybrids designed in the past five years discussing their design principles, results and highlights their future perspectives.

Flavonoids as Inhibitors of Bacterial Efflux Pumps

Flavonoids are widely occurring secondary plant constituents, and are abundant in vegetable and fruit diets as well as herbal medicines. Therapeutic treatment options for bacterial infections are limited due to the spread of antimicrobial resistances. Hence, in a number of studies during the last few years, different classes of plant secondary metabolites as resistance-modifying agents have been carried out. In this review, we present the role of flavonoids as inhibitors of bacterial efflux pumps. Active compounds could be identified in the subclasses of chalcones, flavan-3-ols, flavanones, flavones, flavonols, flavonolignans and isoflavones; by far the majority of compounds were aglycones, although some glycosides like kaempferol glycosides with p-coumaroyl acylation showed remarkable results. Staphylococcus aureus NorA pump was the focus of many studies, followed by mycobacteria, whereas Gram-negative bacteria are still under-investigated.

Chalcone-Derived Nrf2 Activator Protects Cognitive Function via Maintaining Neuronal Redox Status

NF-E2-related factor 2 (Nrf2), the key transcription regulator of phase II enzymes, has been considered beneficial for neuronal protection. We previously designed a novel chalcone analog, 1-(2,3,4-trimethoxyphenyl)-2-(3,4,5-trimethoxyphenyl)-acrylketone (Tak), that could specifically activate Nrf2 in vitro. Here, we report that Tak confers significant hippocampal neuronal protection both in vitro and in vivo. Treatment with Tak has no significant toxicity on cultured neuronal cells. Instead, Tak increases cellular ATP production by increasing mitochondrial function and decreases the levels of reactive oxygen species by activating Nrf2-mediated phase II enzyme expression. Tak pretreatment prevents glutamate-induced excitotoxic neuronal death accompanied by suppressed mitochondrial respiration, increased superoxide production, and activation of apoptosis. Further investigation indicates that the protective effect of Tak is mediated by the Akt signaling pathway. Meanwhile, Tak administration in mice can sufficiently abrogate scopolamine-induced cognitive impairment via decreasing hippocampal oxidative stress. In addition, consistent benefits are also observed in an energy stress mouse model under a high-fat diet, as the administration of Tak remarkably increases Akt signaling-mediated antioxidative enzyme expression and prevents hippocampal neuronal apoptosis without significant effect on the mouse metabolic status. Overall, our study demonstrates that Tak protects cognitive function by Akt-mediated Nrf2 activation to maintain redox status both vivo and in vitro, suggesting that Tak is a promising pharmacological candidate for the treatment of oxidative neuronal diseases.

(2E)-2-(4-ethoxybenzylidene)-3,4-dihydro-2H-naphthalen-1-one single crystal: Synthesis, growth, crystal structure, spectral characterization, biological evaluation and binding interactions with SARS-CoV-2 main protease

A new α-Tetralone based chalcone compound, (2E)-2-(4-ethoxybenzylidene)-3,4-dihydro-2H-naphthalen-1-one (EBDN) has been synthesized by Claisen–Schmidt condensation reaction of α-Tetralone (1) with 4-Ethoxybenzaldehyde (2) in basic medium. Then it was allowed to grow through slow evaporation solution growth technique. The molecular structure of grown EBDN has been systematically characterized by SCXRD, FT-IR, ¹H NMR and ¹³C NMR spectroscopic studies. The micro-hardness, thermal (TGA & DTA) and photoluminence studies of the synthesized EBDN were also examined. The EBDN was screened for its anti-inflammatory, antidiabetic and anti-oxidant activity. It has shown admirable anti-inflammatory and antidiabetic activity. Protein-Ligand interactions of EBDN with SARS-CoV-2 main protease (PDB code: 6yb7) also performed.

Flavonoid 4,4'-dimethoxychalcone suppresses cell proliferation via dehydrogenase inhibition and oxidative stress aggravation

Flavonoids are natural polyphenolic compounds with a diverse array of biological activities and health-promoting effects. Recent studies have found that 4,4'-dimethoxychalcone (DMC) promoted longevity via autophagy; however, its targets are currently unknown. Herein, we employed an unbiased thermal proteome profiling (TPP) method and identified multiple targets of DMC, including ALDH1A3, ALDH2, and PTGES2. We further determined the dissociation constant (Kd) of DMC and ALDH1A3 to be 2.8 μM using microscale thermophoresis (MST) analysis, which indicated that DMC inhibited ALDH1A3 activity and aggravated cellular oxidative stress. DMC treatment significantly increased cellular reactive oxygen species (ROS) production and inhibited cancer cell growth. Quantitative proteomic analysis showed that DMC upregulated proteins associated with stress-responses and downregulated proteins associated with cell cycle progression, and this was confirmed using cell cycle analysis. Taken together, we showed that TPP is an effective tool with which to identify flavonoid targets and set a precedent for deciphering flavonoid function in the future. We have demonstrated that DMC inhibited cell proliferation via ROS-induced cell cycle arrest and is an anti-proliferative agent in cancer treatment.

Investigation of the antimicrobial activities of various antimicrobial agents on Streptococcus Mutans Sortase A through computer-aided drug design (CADD) approaches

BACKGROUND AND OBJECTIVE

Tooth decay is a common chronic disease that causes pain, tooth loss, malnutrition, anxiety and significantly affects half of the world's population. Streptococcus mutans (S.mutans), is considered the main pathogen causing tooth decay. Sortase A (SrtA), one of the surface proteins of S. mutans, is a potential target in the development of antimicrobial and caries prevention agents for preventing infections associated with biofilm formation. Recently, various SrtA inhibitors, including small molecules and natural product, especially, trans-chalcone, chlorhexidine (CHX) and flavonoid compounds, which exhibit effective inhibition against SrtA, have been identified. However, due to the limited number of inhibitors, multi-drug resistance and side-effects the discovery of new inhibitors for SrtA is essential.

METHODS

In this case, various compounds aimed at the target enzyme underwent high-throughput screening with small molecule libraries. For this screening of a total of 178 compounds, 163 were found to be pharmacokinetically suitable by performing an absorption, distribution, metabolism, and excretion (ADME) analysis. Molecular docking was then applied to investigate the interaction mechanism among these suitable compounds and the target enzyme structure at the molecular level.

RESULTS

According to the results of the study, six compounds (CHEMBL243796 (kurarinone), CHEMBL2180472, CHEMBL3335591, CHEMBL373249, CHEMBL1395334, CHEMBL253467 (Isobavachalcone)) exhibited lower docking scores (-7.18, -6.59, -6.53, -6.47, -6.43, and -6.39 kcal/mol, respectively) against S. mutans SrtA than the positive control CHX (-6.29 kcal/mol). Finally, the 100 ns molecular dynamic simulations and binding free energy calculations were performed for the structure stability analysis of the enzyme with CHEMBL243796 (kurarinone), which showed the lowest docking score. As a result of these studies, the stability of the critical interactions between kurarinone and the target enzyme was preserved during the simulation time.

CONCLUSIONS

These results indicate that flavonoid and chalcone scaffold compounds are clinically more reliable and potent than CHX as novel inhibitory agents for inhibiting oral biofilm formation. These finding can provide important contribution to the future clinical trials in the development of therapeutically useful inhibitors of SrtA by virtually screening several chemical compounds more rapidly to select suitable compounds for the prevention and treatment of dental caries.

2-Benzylidenebenzofuran-3(2H)-ones as a new class of alkaline phosphatase inhibitors: synthesis, SAR analysis, enzyme inhibitory kinetics and computational studies

The excelling role of organic chemistry in the medicinal field continues to be one of the main leads in the drug development process. Particularly, this industry requires organic chemists to discover small molecular structures with powerful pharmacological potential. Herein, a diverse range of chalcone (1–11) and aurone (12–22) derivatives was designed and synthesized and for the first time, and both motifs were evaluated as potent inhibitors of alkaline phosphatases (APs). Structural identification of the target compounds (1–22) was accomplished using common spectroscopic techniques. The effect of the nature and position of the substituent was interestingly observed and justified based on the detailed structure–activity relationship (SAR) of the target compounds against AP. It was concluded from the obtained results that all the newly synthesized compounds exhibit high inhibitory potential against the AP enzyme. Among them, compounds 12 (IC₅₀ = 2.163 ± 0.048 μM), 15 (IC₅₀ = 2.146 ± 0.056 μM), 16 (IC₅₀ = 2.132 ± 0.034 μM), 18 (IC₅₀ = 1.154 ± 0.043 μM), 20 (IC₅₀ = 1.055 ± 0.029 μM) and 21 (IC₅₀ = 2.326 ± 0.059 μM) exhibited excellent inhibitory activity against AP, and even better/more active than KH₂PO₄ (standard) (IC₅₀ = 2.80 ± 0.065 μM). Remarkably, compound 20 (IC₅₀ = 1.055 ± 0.029 μM) may serve as a lead structure to design more potent inhibitors of alkaline phosphatase. To the best of our knowledge, these synthetic compounds are the most potent AP inhibitors with minimum IC₅₀ values reported to date. Furthermore, a molecular modeling study was performed against the AP enzyme (1EW2) to check the binding interaction of the synthesized compounds 1–22 against the target protein. The Lineweaver–Burk plots demonstrated that most potential derivative 20 inhibited h-IAP via a non-competitive pathway. Finally, molecular dynamic (MD) simulations were performed to evaluate the dynamic behavior, stability of the protein–ligand complex, and binding affinity of the compounds, resulting in the identification of compound 20 as a potential inhibitor of AP. Accordingly, excellent correlation was observed between the experimental and theoretical results. The pharmacological studies revealed that the synthesized analogs 1–22 obey Lipinski's rule. The assessment of the ADMET parameters showed that these compounds possess considerable lead-like characteristics with low toxicity and can serve as templates in drug design.

Aurones are the plant secondary metabolites belonging to the flavonoid’s family. The bioactivities of aurones are very promising, thus these heterocyclic compounds can be considered as an alluring scaffold for drug design and development.

Synthesis, Structural and Biological Properties of the Ring-A Sulfonamido Substituted Chalcones: A Review

Sulfonamidochalcones continue to assert themselves as versatile synthetic intermedi-ates and several articles continue to appear in literature describing their synthesis, chemical transformation and biological properties. These compounds are not only of interest from the medicinal chemistry context, their conformations and crystalline structures also continue to attract attention to explore non-covalent (intramolecular and intermolecular) interactions, control molecular conformations, and improve their physicochemical and optical properties. Despite an exhaustive list of examples of the ring-A sulfonamide-appended chalcones described in the literature, there is no com-prehensive review dedicated to their synthesis, structural and biological properties. This review focuses attention on the synthesis, structure and biological properties of the ring-A sulfonamide-appended chalcones (o/m/p-sulfonamidochalcones) as well as their potential as non-linear optical materials.

Multi-step Synthesis, Characterization and Photophysical Investigation of Novel Biologically Active Heterocyclic Chalcone (AECO)

Novel alkylated heterocyclic chalcone (E)-1-(2-(allyloxy)phenyl)-3-(9-ethyl-9H-carbazol-3-yl)prop-2-en-1-one (AECO) with extended π-bond was prepared by the multi-steps synthesis. The structure of the AECO was established by the spectroscopic technics and purity of the compound was confirmed by the elemental analysis. Physicochemical parameters of the AECO such as molar absorption coefficient, transition dipole moments, stokes shift, oscillator strength and fluorescence quantum yield were calculated in ten various solvents on the basis of polarity of the solvents to see the effect of the solvent with AECO. Interaction of the AECO chromophore with cationic CTAB and anionic SDS surfactants were determined by using the fluorescence spectroscopy techniques. The intensity of the florescence spectrum increase with increasing the concentrations of surfactants. This suggests that strong interaction occurs between AECO with surfactants and this interaction arise from electrostatic forces. So, AECO chromophore could be used as analysis to define the Critical Micelle Concentration (CMC) of the surfactants. In addition the in-vitro antibacterial active of novel heterocyclic chalcone agents four bacteria's strain were evaluated and result showed AECO is beater antibacterial agent against Gram-Negative Bacteria (E. coli and S. flexneri) as compare to the Gram Negative Bacteria with respected to the standard drug Tetracycline.

Design, Synthesis, and Evaluation of Chalcone Derivatives as Multifunctional Agents against Alzheimer's Disease

Fifteen chalcone derivatives 3a-3o were synthesized, and evaluated as multifunctional agents against Alzheimer's disease. In vitro studies revealed that these compounds inhibited self-induced Aβ_1-42 aggregation effectively ranged from 45.9-94.5 % at 20 μM, and acted as potential antioxidants. Their structure-activity relationships were summarized. In particular, (2E)-3-[4-(dimethylamino)phenyl]-1-(pyridin-2-yl)prop-2-en-1-one (3g) exhibited an excellent inhibitory activity of 94.5 % at 20 μM, and it could disassemble the self-induced Aβ_1-42 aggregation fibrils with ratio of 57.1 % at 20 μM concentration. In addition, compound 3g displayed good chelating ability for Cu²⁺ , and could effectively inhibit and disaggregate Cu²⁺ -induced Aβ aggregation. Moreover, compound 3g exerted low cytotoxicity, significantly reversed Aβ_1-42 -induced SH-SY5Y cell damage. More importantly, compound 3g remarkably ameliorated scopolamine-induced memory impairment in mice. In summary, all the results revealed compound 3g was a potential multifunctional agent for AD therapy.

Design, synthesis and antibacterial activity of chalcones against MSSA and MRSA planktonic cells and biofilms

Staphylococcus aureus is the one of the most successful modern pathogens. The same bacterium that lives as a skin and mucosal commensal can be transmitted in health-care and community-settings and causes severe infections. Thus, there is a great challenge for a discovery of novel anti-Staphylococcus aureus compounds, which should act against resistant strains. Herein, we designed and synthesized a series of 17 chalcones, substituted by amino group on ring A, which were evaluated against methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus MRSA planktonic cells. The antibacterial potency was improved by substituents on ring B, which were designed according to Topliss' manual method. 4-bromo-3'-aminochalcone (5f) was the most active, demonstrating minimum inhibitory concentration (MIC) values of 1.9 μg mL^-1 and 7.8 µg mL^-1 against MSSA and MRSA, respectively. The association of 5f with vancomycin demonstrated synergistic effect against MSSA and MRSA, with Fractional Inhibitory Concentration Index (FICI) values of 0.4 and 0.3, respectively. Subinhibitory concentration of 5f inhibited the MSSA and MRSA adhesion to human keratinocytes. Chalcone 5f was able to reduce MSSA and MRSA biofilm formation, as well as acts on preformed biofilm in concentration-dependent mode. Scanning electron microscopy analyses confirmed severe perturbations caused by 5f on MSSA and MRSA biofilm architecture. The acute toxicity assay, using Galleria mellonella larvae, indicated a low toxic effect of 5f after 72 h, displaying lethality of 20% and 30% at 7.8 μg mL^-1 and 78.0 μg mL^-1, respectively. In addition, the antibacterial activity spectrum of 5f indicated action against planktonic cells of Enterococcus faecalis (MIC = 7.8 μg mL^-1), Acinetobacter baumannii (MIC = 15.6 μg mL^-1) and Mycobacterium tuberculosis (MIC = 5.7 μg mL^-1). Altogether, these results open new avenues for 5f as an anti-Staphylococcus aureus agent, with potential applications as antibacterial drug, adjunct of antibiotics and medical devices coating.

Butein induces intrinsic pathway of apoptosis, vimentin proteolysis, and inhibition of cancer stem cell population in a human papillary thyroid cancer cell line

Epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) play an essential role in metastasis of papillary thyroid cancer (PTC). Further mesenchymal marker vimentin is linked with metastasis and cancer stem cell generation. Hence, inhibition of EMT and effective elimination of CSCs offers a novel target for the development of new therapeutic agents. The present study observed that at lower concentration, butein, a major bioactive chalcone, significantly inhibits NPA (papillary thyroid cancer cell line) cell migration and reduces extracellular acidification rate (ECAR) an indicator of enhanced glycolysis, required for cell migration. Additionally, at lower concentrations, butein treatment also suppresses vimentin phosphorylation, an essential step in cell migration, proving its potential against cell migration. Phosphorylation of vimentin is crucial in the protection of vimentin from caspase-mediated proteolysis. Interestingly, butein activates caspase-3 for the apoptosis execution at higher concentration; hence, total levels of vimentin were investigated. Butein induces caspase-3 mediated proteolysis of vimentin. Vimentin and glycolysis are essential for maintaining CSCs; therefore, aldeflour assay and side population assay were performed to investigate the effect of butein on CSCs. Our data suggest butein mediates the reduction in CSCs population. Here we report a novel mechanism of butein mediated inhibition of NPA cells migration by suppressing vimentin phosphorylation and its subsequent proteolysis. Collectively our data suggest the potential of butein as an innovative anticancer therapeutic agent for PTC management.

Biological Activity, Hepatotoxicity, and Structure-Activity Relationship of Kavalactones and Flavokavins, the Two Main Bioactive Components in Kava (Piper methysticum)

Kava (Piper methysticum Forst) is a popular and favorable edible medicinal herb which was traditionally used to prepare a nonfermented beverage with relaxant beneficial for both social and recreational purposes. Numerous studies conducted on kava have confirmed the presence of kavalactones and flavokawains, two major groups of bioactive ingredients, in this miraculous natural plant. Expectedly, both kavalactone and flavokawain components exhibited potent antianxiety and anticancer activities, and their structure-activity relationships were also revealed. However, dozens of clinical data revealed the hepatotoxicity effect which is indirectly or directly associated with kava consumption, and most of the evidence currently seems to point the compounds of flavokawains in kava were responsible. Therefore, our aim is to conduct a systematic review of kavalactones and flavokawains in kava including their biological activities, structure-activity relationships, and toxicities, and as a result of our systematic investigations, suggestions on kava and its compounds are supplied for future research.

Synthesis and biological evaluation of novel ligustrazine-chalcone derivatives as potential anti-triple negative breast cancer agents

A series of novel ligustrazine-chalcone hybrids were synthesized and evaluated for their in vitro and in vivo antitumor activities. The results showed that most of these compounds exhibited significant in vitro cytotoxicity against MDA-MB-231, MCF-7, A549 and HepG2 cell lines with IC50 values as low as sub-micromole. Among them, compounds 6c and 6f possessed better comprehensive characteristics for the antiproliferation effects on both MDA-MB-231 (IC50: 6c, 1.60 ± 0.21 μM; 6f, 1.67 ± 1.25 μM) and MCF-7 (IC50: 6c, 1.41 ± 0.23 μM; 6f, 1.54 ± 0.30 μM). They also exhibited the potent colony-formation inhibitory abilities on above two cell lines in both concentration and time dependent manners, as well as the significantly suppression capabilities against the migration of such cell lines in a concentration dependent manner by wound-healing assay. Of note, compound 6c could significantly induce the apoptosis of MDA-MB-231 cells in a concentration dependent manner and inhibited the transformation of the growth cycle of MDA-MB-231 cells and blocked the cell growth cycle in G0/G1 phase. Moreover, the in vivo antiproliferation assay of compound 6c on TNBC model indicated such compound had a remarkable potency against tumor growth with a widely safety window. Further immunohistochemistry analysis illustrated that compound 6c was provided with a potent capacity to significantly reduce the Ki-67 positive rate in a dose dependent manner. All the results suggested that these hybrids presented both in vitro and in vivo proliferation inhibition potency against breast cancer and further development with good therapeutic potential should be of great interest.

Design, Synthesis, and Anticancer Activity Studies of Novel Quinoline-Chalcone Derivatives

The chalcone and quinoline scaffolds are frequently utilized to design novel anticancer agents. As the continuation of our work on effective anticancer agents, we assumed that linking chalcone fragment to the quinoline scaffold through the principle of molecular hybridization strategy could produce novel compounds with potential anticancer activity. Therefore, quinoline-chalcone derivatives were designed and synthesized, and we explored their antiproliferative activity against MGC-803, HCT-116, and MCF-7 cells. Among these compounds, compound 12e exhibited a most excellent inhibitory potency against MGC-803, HCT-116, and MCF-7 cells with IC50 values of 1.38, 5.34, and 5.21 µM, respectively. The structure-activity relationship of quinoline-chalcone derivatives was preliminarily explored in this report. Further mechanism studies suggested that compound 12e inhibited MGC-803 cells in a dose-dependent manner and the cell colony formation activity of MGC-803 cells, arrested MGC-803 cells at the G2/M phase and significantly upregulated the levels of apoptosis-related proteins (Caspase3/9 and cleaved-PARP) in MGC-803 cells. In addition, compound 12e could significantly induce ROS generation, and was dependent on ROS production to exert inhibitory effects on gastric cancer cells. Taken together, all the results suggested that directly linking chalcone fragment to the quinoline scaffold could produce novel anticancer molecules, and compound 12e might be a valuable lead compound for the development of anticancer agents.

Interaction of 4'-methylflavonoids with biological membranes, liposomes, and human albumin

The aim of the study was to compare the impact of three synthesized chemical compounds from a group of methylated flavonoids, i.e. 2'-hydroxy-4-methylchalcone (3), 4'-methylflavanone (4), and 4'-methylflavone (5), on a red blood cell membranes (RBCMs), phosphatidylcholine model membranes (PC), and human serum albumin (HSA) in order to investigate their structure-activity relationships. In the first stage of the study, it was proved that all of the compounds tested do not cause hemolysis of red blood cells and, therefore, do not have a toxic effect. In biophysical studies, it was shown that flavonoids have an impact on the hydrophilic and hydrophobic regions of membranes (both RBCMs and PC) causing an increase in packing order of lipid heads and a decrease in fluidity, respectively. Whereas, on the one hand, the magnitude of these changes depends on the type of the compound tested, on the other hand, it also depends on the type of membrane. 4'-Methylflavanone and 4'-methylflavone are located mainly in the hydrophilic part of lipid membranes, while 2'-hydroxy-4-methylchalcone has a greater impact on the hydrophobic area. A fluorescence quenching study proved that compounds (3), (4) and (5) bind with HSA in a process of static quenching. The binding process is spontaneous whereas hydrogen bonding interactions and van der Waals forces play a major role in the interaction between the compounds and HSA.

Promising Non-cytotoxic Monosubstituted Chalcones to Target Monoamine Oxidase-B

A library of monosubstituted chalcones (1-17) bearing electron-donating and electron-withdrawing groups on both aromatic rings were selected. The cell viability on human tumor cell lines was evaluated first. The compounds unable to induce detectable cytotoxicity (1, 13, and 14) were tested using the monoamine oxidase (MAO) activity assay. Interestingly, they inhibit MAO-B, acting as competitive inhibitors, with 13 and 14 showing the best profiles. In particular, 13 exhibited a potency higher than that of safinamide, taken as a reference. Docking studies and crystallographic analysis showed that in human MAO-B 13 binds with the halogen-substituted aromatic ring in the entrance cavity, similar to safinamide, whereas 14 is accommodated in the opposite way. The main conclusion of this cell biology, biochemistry, and structural study is to highlights 13 as a chalcone derivative that is worth consideration for the development of novel MAO-B-selective inhibitors for the treatment of neurodegenerative diseases.

Insights on a new sulfonamide chalcone with potential antineoplastic application

Chalcones (E)-1,3-diphenyl-2-propene-1-ones, a class of biosynthetic precursor molecules of flavonoids, have a wide variety of biological applications. Besides the natural products, many synthetic derivatives and analogs became an object of continued interest in academia and industry. In this work, a synthesis and an extensive structural study were performed on a sulfonamide chalcone 1-Benzenesulfonyl-3-(4-bromobenzylidene)-2-(2-chlorophenyl)-2,3-dihydro-1H-quinolin-4-one with potential antineoplastic application. In addition, in silico experiments have shown that the sulfonamide chalcone fits well in the ligand-binding site of EGFR with seven μ-alkyl binding energy interactions on the ligand-binding site. Finally, the kinetic stability and the pharmacophoric analysis for EGFR indicated the necessary spatial characteristics for potential activity of sulfonamide chalcone as an antagonist.

Chalcone Derivatives: Role in Anticancer Therapy

Chalcones (1,3-diaryl-2-propen-1-ones) are precursors for flavonoids and isoflavonoids, which are common simple chemical scaffolds found in many naturally occurring compounds. Many chalcone derivatives were also prepared due to their convenient synthesis. Chalcones as weandhetic analogues have attracted much interest due to their broad biological activities with clinical potentials against various diseases, particularly for antitumor activity. The chalcone family has demonstrated potential in vitro and in vivo activity against cancers via multiple mechanisms, including cell cycle disruption, autophagy regulation, apoptosis induction, and immunomodulatory and inflammatory mediators. It represents a promising strategy to develop chalcones as novel anticancer agents. In addition, the combination of chalcones and other therapies is expected to be an effective way to improve anticancer therapeutic efficacy. However, despite the encouraging results for their response to cancers observed in clinical studies, a full description of toxicity is required for their clinical use as safe drugs for the treatment of cancer. In this review, we will summarize the recent advances of the chalcone family as potential anticancer agents and the mechanisms of action. Besides, future applications and scope of the chalcone family toward the treatment and prevention of cancer are brought out.

Trimethoxylated Halogenated Chalcones as Dual Inhibitors of MAO-B and BACE-1 for the Treatment of Neurodegenerative Disorders

Six halogenated trimethoxy chalcone derivatives (CH1-CH6) were synthesized and spectrally characterized. The compounds were further evaluated for their inhibitory potential against monoamine oxidases (MAOs) and β-secretase (BACE-1). Six compounds inhibited MAO-B more effectively than MAO-A, and the 2',3',4'-methoxy moiety in CH4-CH6 was more effective for MAO-B inhibition than the 2',4',6'-methoxy moiety in CH1-CH3. Compound CH5 most potently inhibited MAO-B, with an IC50 value of 0.46 µM, followed by CH4 (IC50 = 0.84 µM). In 2',3',4'-methoxy derivatives (CH4-CH6), the order of inhibition was -Br in CH5 > -Cl in CH4 > -F in CH6 at the para-position in ring B of chalcone. CH4 and CH5 were selective for MAO-B, with selectivity index (SI) values of 15.1 and 31.3, respectively, over MAO-A. CH4 and CH5 moderately inhibited BACE-1 with IC50 values of 13.6 and 19.8 µM, respectively. When CH4 and CH5 were assessed for their cell viability studies on the normal African Green Monkey kidney cell line (VERO) using MTT assays, it was noted that both compounds were found to be safe, and only a slightly toxic effect was observed in concentrations above 200 µg/mL. CH4 and CH5 decreased reactive oxygen species (ROS) levels of VERO cells treated with H2O2, indicating both compounds retained protective effects on the cells by antioxidant activities. All compounds showed high blood brain barrier permeabilities analyzed by a parallel artificial membrane permeability assay (PAMPA). Molecular docking and ADME prediction of the lead compounds provided more insights into the rationale behind the binding and the CNS drug likeness. From non-test mutagenicity and cardiotoxicity studies, CH4 and CH5 were non-mutagenic and non-/weak-cardiotoxic. These results suggest that CH4 and CH5 could be considered candidates for the cure of neurological dysfunctions.

Recent advancements in anti-leishmanial research: Synthetic strategies and structural activity relationships

Leishmaniasis is a parasitic neglected tropical disease caused by various species of Leishmania parasite. Despite tremendous advancements in the therapeutic sector and drug development strategies, still the existing anti-leishmanial agents are associated with some clinical issues like drug resistance, toxicity and selectivity. Therefore, several research groups are continuously working towards the development of new therapeutic candidates to overcome these issues. Many potential heterocyclic moieties have been explored for this purpose including triazoles, chalcones, chromone, thiazoles, thiosemicarbazones, indole, quinolines, etc. It is evident from the literature that the majority of anti-leishmanial agents act by interacting with key regulators including PTR-I, DHFR, LdMetAP1, MAPK, 14 α-demethylase and pteridine reductase-I, etc. Also, these tend to induce the production of ROS which causes damage to parasites. In the present compilation, authors have summarized various significant synthetic procedures for anti-leishmanial agents reported in recent years. A brief description of the pharmacological potentials of synthesized compounds along with important aspects related to structural activity relationship has been provided. Important docking outcomes highlighting the possible mode of interaction for the reported compounds have also been included. This review would be helpful to the scientific community to design newer strategies and also to develop novel therapeutic candidates against leishmaniasis.

Trimethoxy Crown Chalcones as Multifunctional Class of Monoamine Oxidase Enzyme Inhibitors

BACKGROUND

Chalcones with methoxy substituents are considered as a promising framework for the inhibition of monoamine oxidase (MAO) enzymes.

METHODS

A series of nine trimethoxy substituted chalcones (TMa-TMi) was synthesized and evaluated as a multifunctional class of MAO inhibitors. All the synthesized compounds were investigated for their in vitro MAO inhibition, kinetics, reversibility, blood-brain barrier (BBB) permeation, and cytotoxicity and antioxidant potentials.

RESULTS

In the present study, compound (2E)-3-(4-nitrophenyl)-1-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (TMf) was provided with an MAO-A inhibition constant value equal to 3.47±0.09 μM and with a selectivity of 0.008. Thus, it was comparable to that of moclobemide, a well known potent hMAO-A inhibitor (SI=0.010). Compound (2E)-3-(4-bromophenyl)-1-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (TMh) showed good MAO-B inhibition, with an inhibition constant of 0.46±0.009 μM. The PAMPA assay demonstrated that all the synthesized derivatives can cross the BBB successfully. The cytotoxicity studies revealed that TMf and TMh have 88.22 and 80.18 % cell viability at 25 µM. Compound TMf appeared as the most promising antioxidant molecule with IC₅₀ values, relative to DPPH and H₂O₂ radical activities, equal to 6.02±0.17 and 7.25±0.07 μM. To shed light on the molecular interactions of TMf and TMh towards MAO-A and MAO-B, molecular docking simulations and MM/GBSA calculations have been carried out.

CONCLUSION

The lead molecules TMf and TMh with multi-functional nature can be further employed for the treatment of various neurodegenerative disorders and depressive states.

Design, synthesis, and molecular docking study of novel quinoline-based bis-chalcones as potential antitumor agents

A novel series of quinoline-based symmetrical and unsymmetrical bis-chalcones was synthesized via a Claisen-Schmidt condensation reaction between 3-formyl-quinoline/quinolone derivatives with acetone or arylidene acetones, respectively, by using KOH/MeOH/H₂ O as a reaction medium. Twelve of the obtained compounds were evaluated for their in vitro cytotoxic activity against 60 different human cancer cell lines according to the National Cancer Institute protocol. Among the screened compounds, the symmetrical N-butyl bis-quinolinyl-chalcone 14g and the unsymmetrical quinolinyl-bis-chalcone 17o bearing a 7-chloro-substitution on the N-benzylquinoline moiety and 4-hydroxy-3-methoxy substituent on the phenyl ring, respectively, exhibited the highest overall cytotoxicity against the evaluated cell lines with a GI₅₀ range of 0.16-5.45 µM, with HCT-116 (GI₅₀  = 0.16) and HT29 (GI₅₀  = 0.42 μM) (colon cancer) representing best-case scenarios. Notably, several GI₅₀ values for these compounds were lower than those of the reference drugs doxorubicin and 5-FU. Docking studies performed on selected derivatives yielded very good binding energies in the active site of proteins that participate in key carcinogenic pathways.

Recent Advances in bis-Chalcone-Based Photoinitiators of Polymerization: From Mechanistic Investigations to Applications

Over the past several decades, photopolymerization has become an active research field, and the ongoing efforts to develop new photoinitiating systems are supported by the different applications in which this polymerization technique is involved-including dentistry, 3D and 4D printing, adhesives, and laser writing. In the search for new structures, bis-chalcones that combine two chalcones' moieties within a unique structure were determined as being promising photosensitizers to initiate both the free-radical polymerization of acrylates and the cationic polymerization of epoxides. In this review, an overview of the different bis-chalcones reported to date is provided. Parallel to the mechanistic investigations aiming at elucidating the polymerization mechanisms, bis-chalcones-based photoinitiating systems were used for different applications, which are detailed in this review.

Photophysical Study and Biological Applications of Synthetic Chalcone-Based Fluorescent Dyes

A chalcone series (3a–f) with electron push–pull effect was synthesized via a one-pot Claisen–Schmidt reaction with a simple purification step. The compounds exhibited strong emission, peaking around 512–567 nm with mega-stokes shift (∆λ = 93–139 nm) in polar solvents (DMSO, MeOH, and PBS) and showed good photo-stability. Therefore, 3a–f were applied in cellular imaging. After 3 h of incubation, green fluorescence was clearly brighter in cancer cells (HepG2) compared to normal cells (HEK-293), suggesting preferential accumulation in cancer cells. Moreover, all compounds exhibited higher cytotoxicity within 24 h toward cancer cells (IC₅₀ values ranging from 45 to 100 μM) than normal cells (IC₅₀ value >100 μM). Furthermore, the antimicrobial properties of chalcones 3a–f were investigated. Interestingly, 3a–f exhibited antibacterial activities against Escherichia coli and Staphylococcus aureus, with minimum bactericidal concentrations (MBC) of 0.10–0.60 mg/mL (375–1000 µM), suggesting their potential antibacterial activity against both Gram-negative and Gram-positive bacteria. Thus, this series of chalcone-derived fluorescent dyes with facile synthesis shows great potential for the development of antibiotics and cancer cell staining agents.