Phenylsulphonyl urenyl chalcone derivatives as dual inhibitors of cyclo-oxygenase-2 and 5-lipoxygenase

Antiviral and antimicrobial applications of chalcones and their derivatives: From nature to greener synthesis

Chalcones and their derivatives have been widely studied due to their versatile pharmacological and biological activities, such as anti-inflammatory, antibacterial, antiviral, and antitumor effects. These compounds have shown suitable antiviral effects through the selective targeting of a variety of viral enzymes, including lactate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fumarate reductase, protein tyrosine phosphatase, topoisomerase-II, protein kinases, integrase/protease, and lactate/isocitrate dehydrogenase, among others. Chalcones and their derivatives have displayed excellent potential for combating pathogenic bacteria and fungi (especially, multidrug-resistant bacteria). However, relevant mechanisms should be further explored, focusing on inhibitory effects against DNA gyrase B, UDP-N-acetylglucosamine enolpyruvyl transferase (MurA), and efflux pumps (e.g., NorA), among others. In addition, the antifungal and antiparasitic activities of these compounds (e.g., antitrypanosomal and antileishmanial properties) have prompted additional explorations. Nonetheless, systematic analysis of the relevant mechanisms, biosafety issues, and pharmacological properties, as well as clinical translation studies, are vital for practical applications. Herein, recent advancements pertaining to the antibacterial, antiviral, antiparasitic, and antifungal activities of chalcones and their derivatives are deliberated, focusing on the relevant mechanisms of action, crucial challenges, and future prospects. Furthermore, due to the great importance of greener and more sustainable synthesis of these valuable compounds, especially on an industrial scale, the progress made in this field has been briefly discussed. Hopefully, this review can serve as a catalyst for researchers to delve deeper into the exploration and designing of novel chalcone compounds with medicinal properties, especially against pathogenic viruses and multidrug-resistant bacteria as major causes of concern for human health.

Pharmacological Properties of Chalcones: A Review of Preclinical Including Molecular Mechanisms and Clinical Evidence

Chalcones are among the leading bioactive flavonoids with a therapeutic potential implicated to an array of bioactivities investigated by a series of preclinical and clinical studies. In this article, different scientific databases were searched to retrieve studies depicting the biological activities of chalcones and their derivatives. This review comprehensively describes preclinical studies on chalcones and their derivatives describing their immense significance as antidiabetic, anticancer, anti-inflammatory, antimicrobial, antioxidant, antiparasitic, psychoactive, and neuroprotective agents. Besides, clinical trials revealed their use in the treatment of chronic venous insufficiency, skin conditions, and cancer. Bioavailability studies on chalcones and derivatives indicate possible hindrance and improvement in relation to its nutraceutical and pharmaceutical applications. Multifaceted and complex underlying mechanisms of chalcone actions demonstrated their ability to modulate a number of cancer cell lines, to inhibit a number of pathological microorganisms and parasites, and to control a number of signaling molecules and cascades related to disease modification. Clinical studies on chalcones revealed general absence of adverse effects besides reducing the clinical signs and symptoms with decent bioavailability. Further studies are needed to elucidate their structure activity, toxicity concerns, cellular basis of mode of action, and interactions with other molecules.

Chalcones as Scavengers of HOCl and Inhibitors of Oxidative Burst: Structure-Activity Relationship Studies

AIMS

Evaluate the ability of chalcones to scavenge hypochlorous acid (HOCl) and modulate oxidative burst.

BACKGROUND

The chemistry of chalcones has long been a matter of interest to the scientific community due to the phenolic groups often present and to the various replaceable hydrogens that allow the formation of a broad number of derivatives. Due to this chemical diversity, several biological activities have been attributed to chalcones, namely anti-diabetic, anti-inflammatory and antioxidant.

OBJECTIVES

Evaluate the ability of a panel of 34 structurally related chalcones to scavenge HOCl and/or suppress its produc-tion through the inhibition of human neutrophils' oxidative burst, followed by the establishment of the respective structure-activity relationships.

METHODS

The ability of chalcones to scavenge HOCl was evaluated by fluorimetric detection of the inhibition of dihydro-rhodamine 123 oxidation. The ability of chalcones to inhibit neutrophils' oxidative burst was evaluated by chemiluminomet-ric detection of the inhibition of luminol oxidation.

RESULTS

It was observed that the ability to scavenge HOCl depends on the position and number of hydroxy groups on both aromatic rings. Chalcone 5b was the most active with an IC50 value of 1.0 ± 0.1 μM. The ability to inhibit neutrophils' oxi-dative burst depends on the presence of a 2'-hydroxy group on A-ring and on other substituents groups, e.g. methoxy, hy-droxy, nitro and/or chlorine atom(s) at C-2, C-3 and/or C-4 on B-ring, as in chalcones 2d, 2f, 2j, 2i, 4b, 2n and 1d, which were the most actives with IC50 values ranging from 0.61 ± 0.02 μM to 1.7 ± 0.2 μM.

CONCLUSION

The studied chalcones showed high activity at a low micromolar range, indicating their potential as antioxidant agents and to be used as a molecular structural scaffold for the design of new anti-inflammatory compounds.

Design, synthesis, and biological evaluation of new pyrazoloquinazoline derivatives as dual COX-2/5-LOX inhibitors

A new series of pyrazoloquinazoline derivatives equipped with different chalcones was designed, synthesized, and identified through ¹ H nuclear magnetic resonance (NMR), ¹³ C NMR, and infrared spectroscopic techniques. Our design strategy of the quinazolinone-privileged scaffold as a new scaffold was based on merging pharmacophores previously reported to exhibit cyclooxygenase-2 (COX-2)/5-lipoxygenase (5-LOX) inhibitory activity. All the newly synthesized derivatives were biologically evaluated for COX and 5-LOX inhibitory activity and COX-2 selectivity, using celecoxib and zileuton as reference drugs, as they exhibited promising anti-inflammatory activity. Compound 3j was found to be the most promising derivative, with IC₅₀ values of 667 and 47 nM against COX-1 and COX-2, respectively, which are superior to that of celecoxib (IC₅₀ value against COX-2 = 95 nM), showing an SI of 14.2 that was much better than celecoxib. Compounds 3f and 3h exhibited COX-1 inhibition, with IC₅₀ values of 1,485 and 684 nM, respectively. The synthesized compounds showed a significant inhibitory activity against 5-LOX, with IC₅₀ values ranging from 0.6 to 4.3 µM, where compounds 3f and 3h were found to be the most potent derivatives, with IC₅₀ values of 0.6 and 1.0 µM, respectively, in comparison with that of zileuton (IC₅₀  = 0.8 µM). These promising derivatives, 3f, 3h, and 3j, were further investigated in vivo for anti-inflammatory, gastric ulcerogenic effects, and prostaglandin production (PGE2) in rat serum. The molecular docking studies concerning the binding sites of COX-2 and 5-LOX revealed similar orientation, compared with reported inhibitors, which encouraged us to design new leads targeting COX-2 and 5-LOX as dual inhibitors, as a new avenue in anti-inflammatory therapy.

Chalcone-Thiazole Hybrids: Rational Design, Synthesis, and Lead Identification against 5-Lipoxygenase

A hybrid pharmacophore approach is used to design and synthesize novel chalcone-thiazole hybrid molecules. Herein, thiazole has been hybridized with chalcone to obtain a new class of 5-LOX inhibitors. In vitro biological evaluation showed that most of the compounds were better 5-LOX inhibitors than the positive control, Zileuton (IC₅₀ = 1.05 ± 0.03 μM). The best compounds in the series, namely, 4k, 4n, and 4v (4k: IC₅₀ = 0.07 ± 0.02 μM, 4n: IC₅₀ = 0.08 ± 0.05 μM, 4v: 0.12 ± 0.04 μM) are found to be 10 times more active than previously reported 2-amino thiazole (2m: IC₅₀ = 0.9 ± 0.1 μM) by us. Further, 4k has redox (noncompetitive) while 4n and 4v act through a competitive inhibition mechanism. SAR indicated that the presence of methoxy/methyl either in the vicinity of chalcone or both thiazole and chalcone contributed to the synergistic inhibitory effect.

Promising anti-inflammatory effects of chalcones via inhibition of cyclooxygenase, prostaglandin E2, inducible NO synthase and nuclear factor κb activities

Chalcones (1, 3-Diphenyl-2-propen-1-one) consist of a three carbon α, β-unsaturated carbonyl system and act as precursors for the biosynthesis of flavonoids in plants. However, laboratory synthesis of various chalcones has also been reported. Both natural and synthetic chalcones are known to exhibit a variety of pharmacological activities such as anti-inflammatory, antitumor, antibacterial, antifungal, antimalarial and antituberculosis. These promising activities, ease of synthesis and simple chemical structure have awarded chalcones considerable attraction. This review focuses on the anti-inflammatory effects of chalcones, caused by their inhibitory action primarily against the activities and expressions of four key inflammatory mediators viz., cyclooxygenase, prostaglandin E₂, inducible NO synthase, and nuclear factor κB. Various methodologies for the synthesis of chalcones have been discussed. The potency of recently synthesized chalcones is given in terms of their IC₅₀ values. Structure-Activity Relationships (SARs) of a variety of chalcone derivatives have been discussed. Computational methods were applied to calculate the ideal orientation of a typical chalcone scaffold against three enzymes, namely, cyclooxygenase-1, cyclooxygenase-2 and inducible NO synthase for the formation of stable complexes. The global market of anti-inflammatory drugs and its expected growth (from 2018 to 2026) have been discussed. SAR analysis, docking studies, and future prospects all together provide useful clues for the synthesis of novel chalcones of improved anti-inflammatory activities.

Safer anti-inflammatory therapy through dual COX-2/5-LOX inhibitors: A structure-based approach

Inflammatory mediators of the arachidonic acid cascade from cyclooxygenase (COX) and lipoxygenase (LOX) pathways are primarily responsible for many diseases in human beings. Chronic inflammation is associated with the pathogenesis and progression of cancer, arthritis, autoimmune, cardiovascular and neurological diseases. Traditional non-steroidal anti-inflammatory agents (tNSAIDs) inhibit cyclooxygenase pathway non-selectively and produce gastric mucosal damage due to COX-1 inhibition and allergic reactions and bronchospasm resulting from increased leukotriene levels. 'Coxibs' which are selective COX-2 inhibitors cause adverse cardiovascular events. Inhibition of any of these biosynthetic pathways could switch the metabolism to the other, which can lead to fatal side effects. Hence, there is undoubtedly an urgent need for new anti-inflammatory agents having dual mechanism that prevent release of both prostaglandins and leukotrienes. Though several molecules have been synthesized with this objective, their unfavourable toxicity profile prevented them from being used in clinics. Here, this integrative review attempts to identify the promising pharmacophore that serves as dual inhibitors of COX-2/5-LOX enzymes with improved safety profile. A better acquaintance of structural features that balance safety and efficacy of dual inhibitors would be a different approach to the process of understanding and interpreting the designing of novel anti-inflammatory agents.

Immunosuppressive Effects of Natural α,β-Unsaturated Carbonyl-Based Compounds, and Their Analogs and Derivatives, on Immune Cells: A Review

The immune system is complex and pervasive as it functions to prevent or limit infections in the human body. In a healthy organism, the immune system and the redox balance of immune cells maintain homeostasis within the body. The failure to maintain the balance may lead to impaired immune response and either over activity or abnormally low activity of the immune cells resulting in autoimmune or immune deficiency diseases. Compounds containing α,β-unsaturated carbonyl-based moieties are often reactive. The reactivity of these groups is responsible for their diverse pharmacological activities, and the most important and widely studied include the natural compounds curcumin, chalcone, and zerumbone. Numerous studies have revealed the mainly immunosuppressive and anti-inflammatory activities of the aforesaid compounds. This review highlights the specific immunosuppressive effects of these natural α,β-unsaturated carbonyl-based compounds, and their analogs and derivatives on different types of immune cells of the innate (granulocytes, monocytes, macrophages, and dendritic cells) and adaptive (T cells, B cells, and natural killer cells) immune systems. The inhibitory effects of these compounds have been comprehensively studied on neutrophils, monocytes and macrophages but their effects on T cells, B cells, natural killer cells, and dendritic cells have not been well investigated. It is of paramount importance to continue generating experimental data on the mechanisms of action of α,β-unsaturated carbonyl-based compounds on immune cells to provide useful information for ensuing research to discover new immunomodulating agents.

Nonsteroidal Anti-Inflammatory Therapy: A Journey Toward Safety

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy.

Diverse Molecular Targets for Chalcones with Varied Bioactivities

Natural or synthetic chalcones with different substituents have revealed a variety of biological activities that may benefit human health. The underlying mechanisms of action, particularly with respect to the direct cellular targets and the modes of interaction with the targets, have not been rigorously characterized, which imposes challenges to structure-guided rational development of therapeutic agents or chemical probes with acceptable target-selectivity profile. This review summarizes literature evidence on chalcones’ direct molecular targets in the context of their biological activities.

Effects of chalcone derivatives on players of the immune system

The immune system is the defense mechanism in living organisms that protects against the invasion of foreign materials, microorganisms, and pathogens. It involves multiple organs and tissues in human body, such as lymph nodes, spleen, and mucosa-associated lymphoid tissues. However, the execution of immune activities depends on a number of specific cell types, such as B cells, T cells, macrophages, and granulocytes, which provide various immune responses against pathogens. In addition to normal physiological functions, abnormal proliferation, migration, and differentiation of these cells (in response to various chemical stimuli produced by invading pathogens) have been associated with several pathological disorders. The unwanted conditions related to these cells have made them prominent targets in the development of new therapeutic interventions against various pathological implications, such as atherosclerosis and autoimmune diseases. Chalcone derivatives exhibit a broad spectrum of pharmacological activities, such as immunomodulation, as well as anti-inflammatory, anticancer, antiviral, and antimicrobial properties. Many studies have been conducted to determine their inhibitory or stimulatory activities in immune cells, and the findings are of significance to provide a new direction for subsequent research. This review highlights the effects of chalcone derivatives in different types of immune cells.

Synthesis, anticancer and radiosensitizing evaluation of some novel sulfonamide derivatives

In this study, novel series of sulfonamide derivatives were synthesized starting from 2-cyanoacetyl)hydrazono)ethyl)phenyl)benzenesulfonamide 4a and 2-cyanoacetyl)hydrazono)ethyl)phenyl)-4-methylbenzenesulfonamide 4b. Different biologically active moieties as pyrazol, thiophene, pyridine and pyrimidines were introduced in order to investigate their in-vitro anticancer activity, in addition to a novel series of sulfonamide chalcones were synthesized from the reported 4-acetyl-N-(P-tolyl) benzenesulfonamide 3b. The newly synthesized sulfonamide derivatives were characterized by FT-IR, (1)H NMR, (13)C NMR, mass spectroscopy and elemental analyses and were tested for their in-vitro anticancer activity against human tumor liver cell line (HEPG-2). The most potent compounds in this study were compounds 4a, 4b, 5a, 6a, 6b, 8, 9, 11, 13, 18 and 19 which showed higher activity than doxorubicin with IC50 ranging from 11.0 to 31.8 μM. Additionally, eight compounds among the most potent were evaluated for their ability to enhance the cell killing effect of γ-radiation.

Synthesis, analgesic and anti-inflammatory activities of new methyl-imidazolyl-1,3,4-oxadiazoles and 1,2,4-triazoles

Background

Long-term clinical employment of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with significant side effects including gastrointestinal (GI) lesions and kidney toxicity. In this paper we designed and synthesized new imidazolyl-1,3,4-oxadiazoles and 1,2,4-triazoles by molecular hybridization of previously described anti-inflammatory compounds in the hope of obtaining new safer analgesic and anti-inflammatory agents.

Methods

The target structures were synthesized by preparation of 5-methyl-1H-imidazole-4-carboxylic acid ethyl ester 5. The reaction of hydrazine hydrate with this ester afforded the 5-methyl-1H-imidazole-4-carboxylic acid hydrazide 6 which was converted to target compounds 7-15 according to the known procedures. In silico toxicity risk assessment and drug likeness predictions were done, in order to consider the privileges of the synthesized structures as drug candidates.

Results and discussion

The analgesic and anti-inflammatory profile of the synthesized compounds were evaluated by writhing and carrageenan induced rat paw edema tests respectively. Compounds 8, 9 and 11-13 and 15 were active analgesic agents and compounds 8, 9 and 11-13 showed significant anti-inflammatory response in comparison with control. Compounds 11 and 13 were screened for their ulcerogenic activities and none of them showed significant ulcerogenic activity. The active Compounds 11 and 12 showed the highest drug likeness and drug score.

Conclusions

The analgesic and anti-inflammatory activities of title compounds were comparable to that of standard drug indomethacin with a safer profile of activity. The results revealed that both of oxadiazole and triazole scaffolds can be determined as pharmacophores. The in silico predictions and pharmacological evaluations showed that compounds 11 and 12 can be chosen as lead for further investigations.

Synthesis and biological evaluation of some N-arylpyrazoles and pyrazolo[3,4-d]pyridazines as anti-inflammatory agents

A series of 3,4-bis-chalcone-N-arylpyrazoles 3a-k was prepared from diacetyl pyrazoles 2a-e. The reaction of 2d and 2e with hydrazine hydrate gave pyrazolo[3,4-d]pyridazine derivatives 4a-b. Furthermore, the reaction of 2a-e with thiosemicarbazide afforded pyrazolo[3,4-d]pyridazine thiocyanate salts 5a-e. The synthesized compounds were subjected to in vivo anti-inflammatory and ulcerogenic activity measurements, in addition to determination of their in vitro COX selectivity, to give a full profile about their anti-inflammatory activities. Compounds 3c, 3f, 3i, and 3e showed significant anti-inflammatory activity among the synthesized compounds. Moreover, docking studies were performed to give an explanation for their anti-inflammatory activity through COX selectivity.

Synthesis of new chalcone derivatives containing acridinyl moiety with potential antimalarial activity

A series of novel chalcones bearing acridine moiety attached to the amino group in their ring A have been synthesized through noncatalyzed nucleophilic aromatic substitution reaction between various 3'-aminochalcone or 4'-aminochalcones and 9-chloroacridine. The synthesized chalcone derivatives have been characterized and screened for in vitro antimalarial activity against Plasmodium falciparum NF-54. All the chalcones showed complete inhibition at concentration of 10 microg/mL and above while three compounds showed significant inhibition at concentration of 2 microg/mL. The three most active chalcone derivatives were screened for in vivo activity as well, but no significant inhibition in parasitaemia was observed when given intraperitoneally to Plasmodium yoelii infected mice model.

(E)-4-alkoxycarbonylalkylthiochalcones: differentiation of isomeric derivatives by electron ionization mass spectrometry

The principal fragmentation pathways of the molecular ions of 18 new (E)-4-alkoxycarbonylalkylthiochalcones have been investigated. It has been shown that the data derived from electron ionization mass spectra (the relative abundance of the fragment ions and values of coefficients micro) can be used to differentiate the isomers. The fragmentation rules deduced here could help in the characterization of other chalcones of these types.

Hormetic dietary phytochemicals

Compelling evidence from epidemiological studies suggests beneficial roles of dietary phytochemicals in protecting against chronic disorders such as cancer, and inflammatory and cardiovascular diseases. Emerging findings suggest that several dietary phytochemicals also benefit the nervous system and, when consumed regularly, may reduce the risk of disorders such as Alzheimer's and Parkinson's diseases. The evidence supporting health benefits of vegetables and fruits provide a rationale for identification of the specific phytochemicals responsible, and for investigation of their molecular and cellular mechanisms of action. One general mechanism of action of phytochemicals that is emerging from recent studies is that they activate adaptive cellular stress response pathways. From an evolutionary perspective, the noxious properties of such phytochemicals play an important role in dissuading insects and other pests from eating the plants. However at the subtoxic doses ingested by humans that consume the plants, the phytochemicals induce mild cellular stress responses. This phenomenon has been widely observed in biology and medicine, and has been described as 'preconditioning' or 'hormesis.' Hormetic pathways activated by phytochemicals may involve kinases and transcription factors that induce the expression of genes that encode antioxidant enzymes, protein chaperones, phase-2 enzymes, neurotrophic factors, and other cytoprotective proteins. Specific examples of such pathways include the sirtuin-FOXO pathway, the NF-kappaB pathway, and the Nrf-2/ARE pathway. In this article, we describe the hormesis hypothesis of phytochemical actions with a focus on the Nrf2/ARE signaling pathway as a prototypical example of a neuroprotective mechanism of action of specific dietary phytochemicals.

Evaluation of the anti-inflammatory and analgesic activity of Me-UCH9, a dual cyclooxygenase-2/5-lipoxygenase inhibitor

Recently, we reported the dual inhibition of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LO) activity by some phenylsulphonyl urenyl chalcone derivatives. 2,4-dichloro-4'N[N'(4''methylphenylsulphonyl)urenyl] chalcone (Me-UCH9), was selected in the present study to determine its potential anti-inflammatory and analgesic effect after oral administration in several animal models related to the activation of COX-2 and 5-LO pathways. In the zymosan stimulated mouse air pouch model, Me-UCH9, reduced in a dose-dependent manner leukotriene B(4) (LTB(4)) levels in pouch exudates obtained at 4 h, as well as prostaglandin E(2) (PGE(2)) generated through COX-2 activation at 24 h. Tumor necrosis factor alpha (TNF-alpha) and myeloperoxidase activity were also strongly inhibited in this model. Me-UCH9 significantly reduced granuloma size and vascular index determined in the murine air pouch granuloma model of angiogenesis. In the carrageenan-induced paw edema, this compound inhibited inflammatory response and pain, as well as PGE(2) and LTB(4) content in paw edematous fluid. Analgesic properties were corroborated in the murine phenyl-p-benzoquinone-induced writhing test. Finally, Me-UCH9 exerted anti-inflammatory effects in the chronic model of rat adjuvant-induced arthritis, both inhibiting paw swelling and reducing PGE(2) content. Our findings confirm that Me-UCH9 can modulate inflammatory and nociceptive responses in relation to the dual inhibition of COX-2 and 5-LO activities presented by this compound.

Chalcone inhibits the activation of NF-kappaB and STAT3 in endothelial cells via endogenous electrophile

Chalcone, an alpha,beta-unsaturated flavonoid, possesses anti-inflammatory properties. In our present study, we have demonstrated chalcone inhibited IL-6- and LPS-induced ICAM-1 gene expression. In adhesion assay, chalcone reduced the LPS-induced adhesion of THP-1 cells to endothelial cells (ECs). Chalcone was found to abrogate the activation of STAT3 and NF-kappaB in a dose- and time-dependent manner, in IL-6- and LPS-treated ECs. Other flavonoids, quercetin and cyanidin, which lack alpha,beta-unsaturated carbonyl group, showed weaker or no inhibitory effect on both IL-6-induced STAT3 phosphorylation and LPS-induced p65 translocation. However, the electrophilic compounds curcumin and crotonaldehyde, which also contain an alpha,beta-unsaturated carbonyl moiety, mimic the inhibitory effects of chalcone with different efficiencies. In addition, N-acetyl-L-cysteine (NAC) could reverse the inhibition of STAT3 phosphorylation when preincubated with chalcone. The use of buthionine sulfoximine (BSO) to decrease intracellular GSH levels further enhanced the effects of chalcone. On the other hand, in ECs treated with BSO only no abrogation of IL-6-induced STAT3 phosphorylation was observed. We also found that chalcone could reduce the GSH level in vitro. Furthermore, the cellular GSH levels were rapidly reduced after 25 microM chalcone treatment. Following 6 h exposure, however, chalcone treatment rescued the GSH levels in ECs, coincident with the inhibition of STAT3 and NF-kappaB activation. In contrast, chalcone induced expression of thioredoxin reductase and heme-oxygenase genes after prolonged treatment. Furthermore, chalcone upregulated the levels of the transcription factor Nrf2 in nuclear extracts and increased antioxidant response element (ARE)-luciferase activity and thioredoxin reductase promoter activity. Hence, our present findings indicate that chalcone suppresses both IL-6- and LPS-induced signaling pathways through the thiol-dependent intracellular redox state. In addition, chalcone may provide distinct cytoprotective effects at different durations of pretreatment.