Synthetic chalcones as potential anti-inflammatory and cancer chemopreventive agents

A boronic acid chalcone analog of combretastatin A-4 as a potent anti-proliferation agent

Chalcones represent a class of natural products that inhibits tubulin assembly. In this study we designed and synthesized boronic acid analogs of chalcones in an effort to compare biological activities with combretastatin A-4, a potent inhibitor of tubulin polymerization. Systematic evaluation of the positional effects of the carbonyl moiety towards inhibition of tubulin polymerization, cancer cell proliferation and angiogenesis revealed that placement of the carbonyl adjacent to the trimethoxybenzene A-ring resulted in more active compounds than when the carbonyl group was placed adjacent to the C-ring. Our study identified a boronic acid chalcone with inhibition towards 16 human cancer cell lines in the 10-200nM range, and another three cell lines with GI(50)-values below 10nM. Furthermore, this drug has significant anti-angiogenesis effects demonstrated by HUVEC tube formation and aortic ring assay.

Synthesis and biological evaluation of 3',4',5'-trimethoxychalcone analogues as inhibitors of nitric oxide production and tumor cell proliferation

A series of 23 3',4',5'-trimethoxychalcone analogues was synthesized and their inhibitory effects on nitric oxide (NO) production in LPS/IFN-gamma-treated macrophages, and tumor cell proliferation has been investigated. 4-Hydroxy-3,3',4',5'-tetramethoxychalcone (7), 3,4-dihydroxy-3',4',5'-trimethoxychalcone (11), 3-hydroxy-3',4,4',5'-tetramethoxychalcone (14), and 3,3',4',5'-tetramethoxychalcone (15) were the most potent growth inhibitory agents on NO production, with an IC(50) value of 0.3, 1.5, 1.3 and 0.3 microM, respectively. The tumor cells proliferation assay results revealed that several compounds exhibited potent inhibition activity against different cancer cell lines. The chalcone 15 was the most potent anti-proliferative compound in the series with IC(50) values of 1.8 and 2.2 microM toward liver cancer Hep G2 and colon cancer Colon 205 cell lines, respectively. 2,3,3',4',5'-Pentamethoxychalcone (1), 3,3',4,4',5,5'-hexamethoxychalcone (3), 2,3',4,4',5,5'-hexamethoxychalcone (5), 2-hydroxy-3,3',4',5'-tetramethoxychalcone (10), 11 and 14 showed significant anti-proliferation actions in Hep G2 and Colon 205 cells with an IC(50) values ranging between 10 and 20 microM. Among the tested agents, compound 7 showed selective NO production inhibition (IC(50)=0.3 microM), while has no effect on tumor cell proliferation (IC(50) >100 microM). 3,3',4,4',5'-Pentamethoxychalcone (2) showed selective anti-proliferation effect in Hep G2 cells, in addition to its potent NO inhibition, however has no such response in Colon 205 cells. In contrast, 3-formyl-3',4',5'-trimethoxychalcone (22) showed moderate growth inhibition in Colon 205 cells, while has no such effect on NO production and Hep G2 cells proliferation. These results provide insight into the correlation between some structural properties of 3',4',5'-trimethoxychalcones and their in vitro anti-inflammatory and anti-cancer differentiation activity.

Evaluation of anti-inflammatory and analgesic activity of a novel rigid 3, 4-dihydroxy chalcone in mice

There have been many reports indicating the analgesic and anti-inflammatory effects of 3,4-dihydroxychalcones. We have designed and synthesized a rigid 3,4-dihydroxychalcone (RDHC) as a possible drug effecting inflammation and nociception. The analgesic and anti-inflammatory effects were evaluated by formalin and hot-plate tests, respectively. The results showed that RDHC induced significant antinociceptive and anti-inflammatory effects (P < 0.01). Maximum analgesia (63.7%) was observed at 37.5 mg/kg in the first phase of the formalin test. The effect of RDHC was higher in the chronic phase (inflammation phase) of the formalin test (86.4%, P < 0.01). In addition, a significant analgesia (maximum possible effect; MPE = 30.1%) was observed in the hot plate test 45 min after injection of 37.5 mg/kg RDHC (P < 0.01). As a result of our findings, this new RDHC could be suggested for further pharmacological studies.

Emerging role of Garcinol, the antioxidant chalcone from Garcinia indica Choisy and its synthetic analogs

Garcinol, harvested from Garcinia indica, has traditionally been used in tropical regions and appreciated for centuries; however its biological properties are only beginning to be elucidated. There is ample data to suggest potent antioxidant properties of this compound which have been used to explain most of its observed biological activities. However, emerging evidence suggests that garcinol could be useful as an anti-cancer agent, and it is increasingly being realized that garcinol is a pleiotropic agent capable of modulating key regulatory cell signaling pathways. Here we have summarized the progress of our current research knowledge on garcinol and its observed biological activities. We have also provided an explanation of observed properties based on its chemical structure and provided an insight into the structure and properties of chalcones, the precursors of garcinol. The available data is promising but more detailed investigations into the various properties of this compound, particularly its anti-cancer activity are urgently needed, and it is our hope that this review will stimulate further research for elucidating and appreciating the value of this nature's wonder agent.

(E)-3-[4-(Hex-yloxy)phen-yl]-1-(4-hydroxy-phen-yl)prop-2-en-1-one

In the title compound, C₂₁H₂₄O₃, the enone group adopts an s–cis conformation. The planes of the aromatic rings are inclined at an angle of 6.1 (1)°. The alk­oxy tail is not linear, with the maximum deviation from the least-squares plane being 0.375 (2) Å. Mol­ecules are connected into extended chains along the a axis through O—H⋯O_carbon­yl hydrogen bonds and are inter­linked via C—H⋯O inter­actions to form a two-dimensional array parallel to the ab plane.

(E)-3-(4-Decyl-oxyphen-yl)-1-(2-hydroxy-phen-yl)prop-2-en-1-one

In the title compound, C₂₅H₃₂O₃, the enone group is in an s–cis configuration. The dihedral angle between the benzene rings is 8.84 (7)°. An intra­molecular O—H⋯O inter­action between the keto and hydr­oxy groups forms an S(6) ring motif. Inter­molecular C—H⋯O inter­actions link the mol­ecules into supra­molecular chains along the c axis which are subsequently stacked down the b axis; the crystal structure is further consolidated by C—H⋯π inter­actions.

(E)-3-(4-Hexyl-oxyphen-yl)-1-(3-hydroxy-phen-yl)prop-2-en-one

In the title compound, C(21)H(24)O(3), the enone unit is in the s-cis configuration. The dihedral angle between the benzene rings is 2.18 (4)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O inter-molecular hydrogen bonds, forming inversion dimers. The crystal structure is also consolidated by C-H⋯π inter-actions.

Structural antitumoral activity relationships of synthetic chalcones

Relationships between the structural characteristic of synthetic chalcones and their antitumoral activity were studied. Treatment of HepG2 cells for 24 h with synthetic 2’-hydroxychalcones resulted in apoptosis induction and dose-dependent inhibition of cell proliferation. The calculated reactivity indexes and the adiabatic electron affinities using the DFT method including solvent effects, suggest a structure-activity relationship between the Chalcones structure and the apoptosis in HepG2 cells. The absence of methoxy substituents in the B ring of synthetic 2’-hydroxychalcones, showed the mayor structure-activity pattern along the series.

Structure activity relationship studies of anti-inflammatory TMMC derivatives: 4-dimethylamino group on the B ring responsible for lowering the potency

We previously synthesized 2',4',6'-tris(methoxymethoxy)chalcone (TMMC) derivatives with various substituents on the A ring that showed potent anti-inflammatory effects by inhibiting NO production in RAW 264.7 cells. The 2'-hydroxy group on the A ring could elevate the electrophilicity of Michael addition of GSH and electron donating groups on the A ring could stabilize the GSH adduct by decreasing the acidity of the alpha-hydrogen. Using this interpretation, we tested various substituents on the B ring and established a proper balance between biological activity and the position of the electron donating or electron withdrawing groups on the B ring. In this case, the 2'-hydroxy group was excluded because it could cause the formation of GSSG through a phenoxy radical and can confuse the interpretation of the biological results. Chalcone derivatives without 2'-hydroxy are likely to deplete cellular GSH levels by a Michael addition process. Strong electron donating groups on the B ring, such as 4-dimethylamino group, gave the weakest inhibition of NO production. A 4-dimethyamino group on the B ring could decrease the stability of the GSH adduct by weakening the C-S bond strength through movement of an electron pair on nitrogen via an aromatic ring.

Synthesis and cytotoxic, anti-inflammatory, and anti-oxidant activities of 2',5'-dialkoxylchalcones as cancer chemopreventive agents

In an effort to develop novel anti-tumor, or cancer chemopreventive agents, a series of 2',5'-dialkoxylchalcones were prepared by Claisen-Schmidt condensation of appropriate acetophenones with suitable aromatic aldehyde. In vitro screening revealed low micromolar activity (IC(50)) against several human cancer cell lines. Selective compound 10 induced an accumulation of A549 cells in the G(2)/M phase arrest which was well correlated with inhibitory activity against tubulin polymerization. Cytotoxic compounds 3 and 12 showed significant inhibitory effects on NO production in lipopolysaccharide (LPS)-activated RAW 264.7 macrophage-like cells while cytotoxic compound 10 revealed potent inhibitory effect on TNF-alpha formation in RAW 264.7 cells in response to LPS. Compounds 3 and 10 also showed significant inhibitory effects on xanthine oxidase. The present results suggested that compounds 3 and 10 were potential to be served as cancer chemopreventive agents.

Transition metal complexes with oxygen donor ligands: A synthesis, spectral, thermal and antimicrobial study

Transition metal complexes of chalcones derived from the condensation of 3-acetyl-6-methyl-2H-pyran-2,4(3H)-dione (dehydroacetic acid) and p-methoxybenzaldehyde (HL1) or p-nitrobenzaldehyde (HL2) were synthesized and characterized by elemental analysis, conductometry, thermal analysis, magnetic measurements, IR, 1H-NMR, UV-Vis spectroscopy and a microbial study. From the analytical and thermal data, the stoichiometry of the complexes was found to be 1:2 (metal: ligand). The molar conductance data revealed that all the metal chelates were non-electrolytes. The thermal stability of the complexes was studied by thermogravimetry and the decomposition schemes of the complexes are given. The ligands and their metal complexes were screened for antibacterial activity against Staphylococcus aureus and Escherichia coli, and fungicidal activity against Aspergillus flavus, Curvularia lunata and Penicillium notatum.

Cytotoxic Mannich bases of 6-(3-aryl-2-propenoyl)-2(3H)-benzoxazolones

A series of 12 new Mannich bases with chalcone core structure were synthesized as potential antineoplastic agents, via N-aminomethylation of two parent 6-(3-aryl-2-propenoyl)-2(3H)-benzoxazolones. The newly synthesized compounds as well as the chalcone prototypes were evaluated for cytotoxicity in the human pre-B-cell leukemia cell line BV-173 using the MTT-dye reduction assay. The tested compounds exhibited concentration-dependent cytotoxic effects at low micromolar concentrations. Ten of the Mannich bases characterized by significant activity in BV-173 were further evaluated against the chronic myeloid leukemia cell line K-562 and were found to suppress the growth of these cells at relatively higher concentrations as compared to the former tumor model. Selected Mannich bases induced programmed cell death in BV-173 at a concentration of 2.5muM as evidenced by the encountered DNA-laddering. Taken together our data suggest that the presented heterocyclic chalcone derived Mannich bases necessitate detailed pharmacological evaluation in order to define further the structure activity relationships, in a larger spectrum of tumor models and to elucidate the mechanisms implicated in the observed cytotoxic effects.

Synthesis and pharmacological activity of chalcones derived from 2,4,6-trimethoxyacetophenone in RAW 264.7 cells stimulated by LPS: quantitative structure-activity relationships

Inhibition of nitric oxide (NO) production by altering the expression of induced enzymes involved is potentially an important strategy for obtaining antiinflammatory agents. In the search for hits to obtain lead compounds for new drugs of this class, 14 synthetic chalcones derived from 2,4,6-trimethoxyacetophenone were evaluated in terms of their inhibitory action, in vitro, in relation to NO production in murine macrophages of the line RAW 264.7 induced by bacterial lipopolysaccharides (LPS). All the compounds were obtained by aldolic condensation between the acetophenone and corresponding aldehydes, under basic conditions. The mean IC(50) values, calculated through dose versus inhibitory effect curves, in four independent experiments, varied between 1.34 and 27.60microM, and were compared with the positive control, compound 1400W (IC(50)=3.78microM), a highly selective inhibitor of iNOS (induced nitric oxide synthase). Eight chalcones gave mean IC(50) values less than or equal to those obtained for 1400W, which suggests that these molecules may act as inhibitors of inflammatory process. The QSAR study reveals that electron-withdrawing groups in the B-ring seem to increase the inhibition of nitrite production, mainly when in position 2. A substitution in the ortho position of the A-ring seems to be necessary for the activity.

Synthesis and antimicrobial evaluation of new chalcones containing piperazine or 2,5-dichlorothiophene moiety

Two new series of chalcones have been synthesized by reacting 1-(4-piperazin-1-yl-phenyl)ethanone and 1-(2,5-dichloro-3-thienyl)-1-ethanone with different substituted benzaldehydes in turn by Claisen-Schmidt condensation. The compounds have been characterized by IR, (1)H NMR spectral and microanalysis data. All the synthesized compounds have been evaluated for antimicrobial activity. Some of these derivatives are potentially active against Gram-positive bacteria, Staphylococcus aureus and Escherichia coli while the most potent compound (1) in this study showed MIC(50) value of 2.22 microg/mL against Candida albicans.

Inhibition of superoxide anion and elastase release in human neutrophils by 3'-isopropoxychalcone via a cAMP-dependent pathway

1 Chalcone is abundantly present in the plant kingdom and has various biological activities such as anti-inflammatory and antioxidant. In this study, the semisynthetic chalcone derivative, 3'-isopropoxychalcone (H2O7D), was demonstrated to inhibit the generation of superoxide and the release of elastase, as well as to accelerate resequestration of cytosolic calcium in formyl-L-methionyl-L-leucyl-L-phenylalanine-activated human neutrophils. 2 H2O7D displayed no antioxidant or superoxide-scavenging ability, and it failed to alter the subcellular NADPH oxidase activity. 3 H2O7D induced a substantial increase in cAMP but not cGMP levels. The elevation of cAMP formation by H2O7D was inhibited by adenosine deaminase (ADA). Furthermore, The inhibitory effects of H2O7D were reversed by protein kinase (PK)A inhibitors, as well as ADA and a selective A2a-receptor antagonist. 4 H2O7D inhibited phosphodiesterase (PDE) activities, but it did not alter adenylyl cyclase and soluble guanylyl cyclase activities. These results show that the cAMP-elevating effect of H2O7D results from the inhibition of PDE activity and not from the stimulation of cyclase function. Consistent with this, H2O7D potentiated the PGE(1)-caused inhibitory effects and cAMP formation. 5 In summary, these results indicate that the inhibitory effect of H2O7D is cAMP/PKA dependent, and that it occurs through inhibition of cAMP PDE, which potentiates the autocrine functions of endogenous adenosine. Inhibition of respiratory burst and degranulation in human neutrophils may give this drug the potential to protect against the progression of inflammation.

Synthetic chalcones, flavanones, and flavones as antitumoral agents: biological evaluation and structure-activity relationships

A series of synthetic chalcones, flavanones, and flavones has been synthesized and evaluated for antitumor activity against the human kidney carcinoma cells TK-10, human mammary adenocarcinoma cells MCF-7 (estrogen receptor-positive), and human colon adenocarcinoma cells HT-29. The most active series is the chalcone ones with the best results against TK-10 and HT-29 cells. Fourteen out of 53 analyzed compounds resulted very active against at least two of the studied tumoral cells. Alkaline single cell gel electrophoresis, comet assay, was performed as a study of the chromosomal aberrations promoted by the compounds on normal cells. Four active and two inactive chalcones were studied in the comet assay against normal human kidney cells (HK-2). A structure-activity relationship analysis of these compounds was performed and for 4- and 3,4-disubstituted derivatives a quantitative correlation was obtained in the case of anti-HT-29 activity.

Synthetic 2',5'-dimethoxychalcones as G(2)/M arrest-mediated apoptosis-inducing agents and inhibitors of nitric oxide production in rat macrophages

In an effort to develop novel antitumor or chemopreventive agents, a series of 2',5'-dimethoxychalcone derivatives were prepared by Claisen-Schmidt condensation of appropriate acetophenones with suitable aromatic aldehyde. In vitro screening revealed low micromolar activity (IC(50)) against several human cancer lines. Activity in MCF-7 cells correlated with the ability to induce G(2)/M arrest-mediated apoptosis following drug treatment by the most potent agent, 8, an observation further reinforced by fluorescence microscopy. Compounds 3, 8, and 10 showed potent inhibitory effect on NO production in lipopolysaccharide (LPS)-activated RAW 264.7 macrophage-like cells. The present results demonstrated that 3, 8, and 10 are potential anti-inflammatory and cancer chemopreventive agents.

Anti-inflammatory Activity of the Synthetic Chalcone Derivatives: Inhibition of Inducible Nitric Oxide Synthase-Catalyzed Nitric Oxide Production from Lipopolysaccharide-Treated RAW 264.7 Cells

Chalcones belong to the flavonoid family from plant origin and some of them possess anti-inflammatory activity. Recently, several natural and synthetic chalcone derivatives were reported to inhibit inducible nitric oxide synthase (iNOS)-catalyzed NO production in cell cultures. In the present study, to find the optimal chemical structures and to elucidate their action mechanisms, 41 synthetic chalcones having the substituent(s) on A- and B-rings were prepared and their effects on iNOS-catalyzed NO production were evaluated using lipopolysaccharide (LPS)-treated RAW 264.7 cells. When simultaneously added with LPS, 2'-methoxy-3,4-dichlorochalcone (Ch15), 2'-hydroxy-6'-methoxychalcone (Ch29), 2'-hydroxy-3-bromo-6'-methoxychalcone (Ch31) and 2'-hydroxy-4',6'-dimethoxychalcone (Ch35) among the tested compounds potently inhibited NO production (IC(50)s, 7.1-9.6 muM). The favorable chemical structures were found to be a methoxyl substitution in A-ring at an adjacent position (2' or 6') to carbonyl moiety with/without 2'-(or 6'-)hydroxyl group and 3-halogen substitution in B-ring. When the cellular action mechanisms of Ch15, Ch31 and Ch35 were further examined using Western blotting and electrophoretic mobility shift assay, it was revealed that Ch15 and Ch31 clearly down-regulated iNOS expression while Ch35 did not. Moreover, Ch15 and Ch31 were proved to suppress the nuclear transcription factor-kappaB activation. From the results, it is suggested that certain chalcone derivatives potently inhibit iNOS-catalyzed NO production by the different cellular mechanisms, iNOS down-regulation and/or iNOS inhibition, depending on their chemical structures. These chalcone derivatives may possibly be used as lead compounds for developing new anti-inflammatory agents.

Synthesis and antimycobacterial activity of novel heterocycles

In the present investigation 4-hydroxy-3-methylacetophenone on condensation with various aromatic aldehydes in methanolic KOH solution yielded the corresponding chalcones (CI-CXI). These chalcones were further reacted with hydrazine hydrate in ethanol which led to the formation of pyrazoline derivatives (HI-HXI). The newly synthesized heterocyles were characterized on the basis of their chemical properties and spectroscopic data. All newly synthesized compounds were evaluated for their antimycobacterial activities against Mycobacterium tuberculosis H37Rv. .

Reactivity of Chalcones with 1-Hydroxymethyl Radicals

Reactivity of chalcones with reactive species issued from methanol radiolysis was investigated in the absence or presence of dioxygen. Chalcones are natural antioxidants that are present in fruit and vegetables. Their degradation in the radiolysed solutions was followed by HPLC, NMR, FAB-LSIMS mass spectroscopy and analytical TLC in deaerated solution. Among the 18 identified radiolytic compounds, 16 were new. The formation of the radiolytic products was not influenced by A- and B-ring substitutions. To explain the degradation process, we thus suggested that the primary step was an attack of the alpha,beta-double bond by the 1-hydroxymethyl radical, either at C(alpha) or at C(beta). This step was followed by addition, cyclization or bond dissociations. Different chemical pathways were discussed that implicate the reactive species issued from methanol radiolysis. This paper highlights the relative importance of the different radical species, especially the carbon-centered radical, 1-hydroxymethyl (HMR) and the corresponding oxygen-centered isomer. In addition, an interesting unusual role of dioxygen should be noted; indeed, in the presence of dioxygen, degradation of chalcones was inhibited.

The effects of cardamonin on lipopolysaccharide-induced inflammatory protein production and MAP kinase and NFkappaB signalling pathways in monocytes/macrophages

BACKGROUND AND PURPOSE

In this study we examined the effect of the natural product cardamonin, upon lipopolysaccharide (LPS)-induced inflammatory gene expression in order to attempt to pinpoint the mechanism of action.

EXPERIMENTAL APPROACHES

Cardamonin was isolated from the Greek plant A. absinthium L. Its effects were assessed on LPS-induced nitrite release and iNOS and COX-2 protein expression in two macrophage cell lines. Western blotting was used to investigate its effects on phosphorylation of the mitogen activated protein (MAP) kinases, ERK, JNK and p38 MAP kinase, and activation of the NFkappaB pathway, at the level of IkappaBalpha degradation and phosphorylation of NFkappaB. Also its effects on NFkappaB and GAS/GAF-DNA binding were assessed by EMSA.

KEY RESULTS

Cardamonin concentration-dependently inhibited both NO release and iNOS expression but had no effect on COX-2 expression. It did not affect phosphorylation of the MAP kinases, degradation of IkappaBalpha or phosphorylation of NFkappaB. However, it inhibited NFkappaB DNA-binding in both LPS-stimulated cells and nuclear extracts of the cells (in vitro). It also inhibited IFNgamma-stimulated iNOS induction and GAS/GAF-DNA binding.

CONCLUSIONS AND IMPLICATIONS

These results show that the inhibitory effect of cardamonin on LPS-induced iNOS induction is not mediated via effects on the initial activation of the NFkappaB or MAP kinase pathways but is due to a direct effect on transcription factor binding to DNA. However, although some selectivity in cardamonin's action is implicated by its inability to affect COX-2 expression, its exact mechanism(s) of action has yet to be identified.

Antinociceptive Effects of Synthetic Chalcones Obtained from Xanthoxyline

A wide variety of noxious stimuli are known to induce a sensation of pain evoked in a remote region of the body. Here, we show that chalcones can inhibit the pain provoked by the administration of an intraperitoneal acetic acid (AA). This study investigates the effects of 17 synthetic chalcones in the writhing test, a visceral pain model in mice. The majority of these compounds proved more active than some analgesic drugs, such as aspirin and acetaminophen, two reference drugs used here for comparison. Four chalcones, 9, 10, 16, and 17, were selected for more detailed studies, since they exhibited significant antinociceptive activities and chemical structures of interest. They caused dose-related inhibitions, proving about 15-, 10-, 9-, and 8-fold more active than the standard drugs. When administrated orally, only chalcone 9 proved to be effective. These chalcones might be further used as a model to obtain new and more potent analgesic drugs.

Novel bis(1-acyl-2-pyrazolines) of potential anti-inflammatory and molluscicidal properties

A variety of bis[3-aryl-4,5-dihydro-1H-pyrazol-1-carboxaldehydes] 4a-h were obtained via reaction of bis[1-aryl-2-propen-1-ones] 3a-h with hydrazine hydrate in refluxing formic acid. In addition, the corresponding bis[1-acetyl-3-aryl-4,5-dihydro-1H-pyrazoles] 4i-m were formed through conducting the reaction of 3 with hydrazine hydrate in refluxing acetic acid. The starting bis(2-propen-1-ones) 3a-h were prepared stereoselectively as E,E'-geometric isomer via condensation of bisbenzaldehydes 1a,b with (un)substituted acetophenones 2 in ethanolic KOH solution. Anti-inflammatory as well as ulcerogenic activities of the prepared pyrazolines were evaluated in vivo and compared with that of a standard drug (indomethacin). Many of the tested compounds show remarkable anti-inflammatory properties with an ulcerogenic liability (especially 4f, g, j, and k) lower than that of the standard used drug. Compound 4f was established to be the best effectively prepared anti-inflammatory active pyrazoline derivative and safer than indomethacin with respect to its ulcerogenic liability. Molluscicidal activity of the prepared compounds against Biomphalaria alexandrina snails (the intermediate host of Schistosoma mansoni) was screened. Where, some of the prepared compounds show considerable activities.

Cardamonin, inhibits pro-inflammatory mediators in activated RAW 264.7 cells and whole blood

Some chalcones, such as hydroxychalcones have been reported previously to inhibit major pro-inflammatory mediators such as nitric oxide (NO), prostaglandin E(2) (PGE(2)), tumor necrosis factor-alpha (TNF-alpha) and reactive oxygen species production by suppressing inducible enzyme expression via inhibition of the mitogen-activated protein kinase (MAPK) pathway and nuclear translocation of critical transcription factors. In this report, the effects of cardamonin (2',4'-dihydroxy-6'-methoxychalcone), a chalcone that we have previously isolated from Alpinia rafflesiana, was evaluated upon two cellular systems that are repeatedly used in the analysis of anti-inflammatory bioactive compounds namely RAW 264.7 cells and whole blood. Cardamonin inhibited NO and PGE(2) production from lipopolysaccharide- and interferon-gamma-induced RAW cells and whole blood with IC(50) values of 11.4 microM and 26.8 microM, respectively. Analysis of thromboxane B(2) (TxB(2)) secretion from whole blood either stimulated via the COX-1 or COX-2 pathway revealed that cardamonin inhibits the generation of TxB(2) via both pathways with IC(50) values of 2.9 and 1.1 microM, respectively. Analysis of IC(50) ratios determined that cardamonin was more COX-2 selective in its inhibition of TxB(2) with a ratio of 0.39. Cardamonin also inhibited the generation of intracellular reactive oxygen species and secretion of TNF-alpha from RAW 264.7 cells in a dose responsive manner with IC(50) values of 12.8 microM and 4.6 microM, respectively. However, cardamonin was a moderate inhibitor of lipoxygenase activity when tested in an enzymatic assay system, in which not a single concentration tested was able to cause an inhibition of more than 50%. Our results suggest that cardamonin acts upon major pro-inflammatory mediators in a similar fashion as described by previous work on other closely related synthetic hydroxychalcones and strengthens the conclusion of the importance of the methoxyl moiety substitution on the 4' or 6' locations of the A benzene ring.

Anticancer activities of novel chalcone and bis-chalcone derivatives

A series of novel chalcones and bis-chalcones containing boronic acid moieties has been synthesized and evaluated for antitumor activity against the human breast cancer MDA-MB-231 (estrogen receptor-negative) and MCF7 (estrogen receptor-positive) cell lines and against two normal breast epithelial cell lines, MCF-10A and MCF-12A. These molecules inhibited the growth of the human breast cancer cell lines at low micromolar to nanomolar concentrations, with five of them (1-4, 9) showing preferential inhibition of the human breast cancer cell lines. Furthermore, bis-chalcone 8 exhibited a more potent inhibition of colon cancer cells expressing wild-type p53 than of an isogenic cell line that was p53-null.

Antiproliferative properties of piperidinylchalcones

Methoxylated chalcones bearing N-methylpiperidinyl substituents on ring A inhibited the growth of human tumour cell lines (MCF, HCT 116, and Jurkat) at IC50 values of <5 microM. Investigations on a representative member (12) showed that antiproliferative activity was linked to the disruption of the cell cycle at G1 and G2/M phases. The effect was concentration dependent and was evident at the approximate IC50 of 12. Down regulation of cell cycle regulatory components (CDK4, cyclin B, E2F, and phosphorylated Rb) were observed under similar conditions. Methoxylated chalcones without the piperidinyl substituent were found to exert equally potent and selective antiproliferative activity against HCT 116 tumour cells but did not interfere with cell cycle progression at their IC50 concentrations. The presence of the piperidinyl substituent in the chalcone template is proposed to lend specificity to the mechanism of antiproliferative activity, in addition to promoting a more desirable physicochemical profile.

Synthesis and Biological Evaluation of (E)-3-(Nitrophenyl)-1-(pyrazin-2-yl)prop-2-en-1-ones

The title (E)-(3-nitrophenyl)-1-(pyrazin-2-yl)prop-2-en-1-ones were prepared by the Claisen- Schmidt condensation of acetylpyrazines and 2-nitro-, 3-nitro- and 4-nitrobenzaldehyde in pyridine using diethylamine as the catalyst. The compounds were bioassayed for in vitro antifungal, antimycobacterial and photosynthesis-inhibiting activity. The high potency of (E)-1-(5-tert-butylpyrazin-2-yl)-3-(4-nitrophenyl)prop-2-en-1-one againstMycobacterium tuberculosis(MIC 0.78 μg/ml) and moderate activities of several compounds againstTrichophyton mentagrophytesandCandidaspp. do not support the assumption that phenolic groups are essential for antimycobacterial and antifungal activity of chalcones and their analogues. In fact, the nitro-substituted compounds were superior to the previously described hydroxylated congeners with antimycobacterial activity (MIC ≥ 12.5 μg/ml). The compounds also reduced chlorophyll content in green algaChlorella vulgaris, and some of them inhibited photosynthetic electron transport in spinach chloroplasts as well. The photosynthesis-inhibiting activity of nitro derivatives was lower than that of the corresponding hydroxylated analogues.

Inhibition of lipopolysaccharide-induced expression of inducible nitric oxide synthase by phenolic (3E)-4-(2-hydroxyphenyl)but-3-en-2-one in RAW 264.7 macrophages

The large amount of nitric oxide (NO) produced by inducible NO synthase (iNOS) contributes to cellular injury in inflammatory disease. In the present study, a novel synthetic compound (3E)-4-(2-hydroxyphenyl)but-3-en-2-one (HPB) was found to inhibit lipopolysaccharide (LPS)-induced NO generation, but not through the inhibition of iNOS activity, in RAW 264.7 macrophages. Administration of HPB into mice also inhibited the LPS-induced increase in serum nitrite/nitrate levels. To evaluate the underlying mechanisms of HPB inhibition of NO generation, the expression of the iNOS gene in RAW 264.7 macrophages was examined. HPB abolished the LPS-induced expression of iNOS protein, iNOS mRNA and iNOS promoter activity in a similar concentration-dependent manner. LPS-induced nuclear factor-kappaB (NF-kappaB) DNA binding and NF-kappaB-dependent reporter gene activity were both significantly inhibited by HPB. This effect was mediated through the inhibition of inhibitory factor-kappaBalpha (IkappaBalpha) phosphorylation and degradation, and of p65 nuclear translocation. HPB had no effect on the LPS-induced phosphorylation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinases (MAPK), and c-Jun NH(2)-terminal kinase (JNK). However, HPB suppressed the LPS-induced intracellular reactive oxygen species (ROS) production. These results indicate that HPB down-regulates iNOS gene expression probably through the inhibition of LPS-induced intracellular ROS production, which has been implicated in the activation of NF-kappaB.