Different effects of two cyclic chalcone analogues on redox status of Jurkat T cells

(E)-2-Benzylidenecyclanones: Part XVIII Study the Possible Link between Glutathione Reactivity and Cancer Cell Cytotoxic Effects of Some Cyclic Chalcone Analogs A Comparison of the Reactivity of the Open-Chain and the Seven-Membered Homologs

Non-enzymatic thiol addition into the α,β-unsaturated carbonyl system is associated with several biological effects. In vivo, the reactions can form small-molecule thiol (e.g., glutathione) or protein thiol adducts. The reaction of two synthetic (4'-methyl- and 4'-methoxy substituted) cyclic chalcone analogs with reduced glutathione (GSH) and N-acetylcysteine (NAC) was studied by (high-pressure liquid chromatography-ultraviolet spectroscopy) HPLC-UV method. The selected compounds displayed in vitro cancer cell cytotoxicity (IC₅₀) of different orders of magnitude. The structure of the formed adducts was confirmed by (high-pressure liquid chromatography-mass spectrometry) HPLC-MS. The incubations were performed under three different pH conditions (pH 3.2/3.7, 6.3/6.8, and 8.0/7.4). The chalcones intrinsically reacted with both thiols under all incubation conditions. The initial rates and compositions of the final mixtures depended on the substitution and the pH. The frontier molecular orbitals and the Fukui function were carried out to investigate the effects on open-chain and seven-membered cyclic analogs. Furthermore, machine learning protocols were used to provide more insights into physicochemical properties and to support the different thiol-reactivity. HPLC analysis indicated diastereoselectivity of the reactions. The observed reactivities do not directly relate to the different in vitro cancer cell cytotoxicity of the compounds.

Dimethyl Cardamonin from Fruits of Campomanesia reitziana D. Legrand Promotes Gastroprotection and Gastric Healing Effects in Rodents

Campomanesia reitziana D. Legrand (Myrtaceae) displays antiulcer properties when given to rodents. The major active chemical components of C. reitziana are chalcones, including 4',6'-dihydroxy-2'-methoxy-3',5'-dimethylchalcone or dimethyl cardamonin (DMC); therefore, we hypothesized that this compound could have antiulcer effects and the present study aimed to evaluate its gastroprotective and gastric healing properties. DMC was isolated from the fruits of C. reitziana, and its gastroprotective effect was evaluated by ethanol and indomethacin-induced gastric ulcer models in mice (0.1 mg/kg, i.p. and 1 and 3 mg/kg, p.o.). Oxidative stress and inflammatory parameters were analyzed in the gastric tissue. Moreover, its gastric healing effect was evaluated in rats. In addition, the compound's mode of action was evaluated in vivo and in vitro by measuring H⁺ -K⁺ -ATPase activity. Finally, the cytotoxic potential of DMC was tested in fibroblasts and human gastric adenocarcinoma cells. The DMC reduced the ethanol-induced gastric ulcer in mice by 77 %, increased the adhered mucus, and reduced lipoperoxides levels. The block of nonprotein sulfhydryls (NP-SH) compounds by pretreatment with N-ethylmaleimide (NEM), the inhibition of nitric oxide synthase with Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME), or the antagonism of α₂ receptor using yohimbine reversed the gastroprotective effects of DMC. Furthermore, DMC reduced the acidity of gastric content in pylorus-ligated rats but did not change H⁺ , K⁺ -ATPase (isolated from rabbit) activity in vitro. DMC reduced the lesion area in acetic acid-induced ulcers and decreased myeloperoxidase activity. DMC did not change the viability of fibroblast cells (L929) but reduced the viability of human gastric adenocarcinoma cells (AGS). The results confirmed that DMC could significantly enhance the gastric healing process and prevent ulcers due to improving protective factors on the gastric mucosa and reducing gastric acid secretion.

Reaction of Chalcones with Cellular Thiols. The Effect of the 4-Substitution of Chalcones and Protonation State of the Thiols on the Addition Process. Diastereoselective Thiol Addition

Several biological effects of chalcones have been reported to be associated with their thiol reactivity. In vivo, the reactions can result in the formation of small-molecule or protein thiol adducts. Both types of reactions can play a role in the biological effects of this class of compounds. Progress of the reaction of 4-methyl- and 4-methoxychalcone with glutathione and N-acetylcysteine was studied by the HPLC-UV-VIS method. The reactions were conducted under three different pH conditions. HPLC-MS measurements confirmed the structure of the formed adducts. The chalcones reacted with both thiols under all incubation conditions. The initial rate and composition of the equilibrium mixtures depended on the ratio of the deprotonated form of the thiols. In the reaction of 4-methoxychalcone with N-acetylcysteine under strongly basic conditions, transformation of the kinetic adduct into the thermodynamically more stable one was observed. Addition of S-protonated N-acetylcysteine onto the polar double bonds of the chalcones showed different degrees of diastereoselectivity. Both chalcones showed a Michael-type addition reaction with the ionized and non-ionized forms of the investigated thiols. The initial reactivity of the chalcones and the equilibrium composition of the incubates showed a positive correlation with the degree of ionization of the thiols. Conversions showed systematic differences under each set of conditions. The observed differences can hint at the difference in reported biological actions of 4-methyl- and 4-methoxy-substituted chalcones.

Design, synthesis and biological evaluation of novel imidazole-chalcone derivatives as potential anticancer agents and tubulin polymerization inhibitors

Novel imidazole-chalcone derivatives were designed and synthesized as tubulin polymerization inhibitors and anticancer agents. The antiproliferative activity of the imidazole-chalcone was assessed on some human cancer cell lines including A549 (adenocarcinoma human alveolar basal epithelial cells), MCF-7 (human breast cancer cells), MCF-7/MX (mitoxantrone resistant human breast cancer cells), and HEPG2 (human hepatocellular carcinoma cells). Generally, the imidazole-chalcone derivatives exhibited more cytotoxicity on A549 cancer cells in comparison to the other three cell lines, among them compounds 9j' and 9g showed significant cytotoxicity with IC₅₀ values ranging from 7.05 to 63.43 μM against all the four human cancer cells. The flow cytometry analysis of A549 cancer cells treated with 9g and 9j' displayed that these compounds induced cell cycle arrest at the G2/M phase at low concentrations and increased the number of apoptotic cells (cells in subG1 phase) at higher concentrations. They have also inhibited tubulin polymerization similar to combretastatin A-4 (CA-4). Annexin V binding staining assay in A549 cancer cells revealed that compound 9j' induced apoptosis (early and late). Finally, molecular docking studies of 9j' into the colchicine-binding site of tubulin presented the probable interactions of these compounds with tubulin.

Alternative mechanisms of action for the apoptotic activity of terpenoid-like chalcone derivatives

The structural basis of the cytotoxicity of terpenoid-like chalcone derivatives.

Aldehyde biphenyl chalcones induce immunogenic apoptotic-like cell death and are promising new safe compounds against a wide range of hematologic cancers

Aim: Investigate the apoptotic mechanisms of two new aldehyde biphenyl chalcones on leukemia cells. Materials & methods: From a series of 71 new chalcones, we selected the two most cytotoxic. Results: JA3 and JA7 were cytotoxic not only against hematological malignancies but also against solid tumor and cancer stem cells, yet with no toxicity to normal cells. Moreover, they induced immunogenic apoptotic-like cell death independently of promyelocytic leukemia protein, with extensive mitochondrial damages downstream of endoplasmic reticulum stress. Preventing endoplasmic reticulum stress and the upregulation of proapoptotic machinery inhibited JA3- and JA7-induced cell death. Likewise, blocking receptor Fas protected cells from killing. They increased the antileukemic effect of cytarabine and vincristine and killed leukemic cells collected from patients with different acute leukemia subtypes. Conclusion: JA3 and JA7 represent new promising prototypes for the development of new chemotherapeutics.

Antiproliferative Effect of Acridine Chalcone Is Mediated by Induction of Oxidative Stress

Chalcones are naturally occurring phytochemicals with diverse biological activities including antioxidant, antiproliferative, and anticancer effects. Some studies indicate that the antiproliferative effect of chalcones may be associated with their pro-oxidant effect. In the present study, we evaluated contribution of oxidative stress in the antiproliferative effect of acridine chalcone 1C ((2 E)-3-(acridin-9-yl)-1-(2,6-dimethoxyphenyl)prop-2-en-1-one) in human colorectal HCT116 cells. We demonstrated that chalcone 1C induced oxidative stress via increased reactive oxygen/nitrogen species (ROS/RNS) and superoxide production with a simultaneous weak adaptive activation of the cellular antioxidant defence mechanism. Furthermore, we also showed chalcone-induced mitochondrial dysfunction, DNA damage, and apoptosis induction. Moreover, activation of mitogen activated phosphokinase (MAPK) signalling pathway in 1C-treated cancer cells was also observed. On the other hand, co-treatment of cells with strong antioxidant, N-acetyl cysteine (NAC), significantly attenuated all of the above-mentioned effects of chalcone 1C, that is, decreased oxidant production, prevent mitochondrial dysfunction, DNA damage, and induction of apoptosis, as well as partially preventing the activation of MAPK signalling. Taken together, we documented the role of ROS in the antiproliferative/pro-apoptotic effects of acridine chalcone 1C. Moreover, these data suggest that this chalcone may be useful as a promising anti-cancer agent for treating colon cancer.

Antioxidant Mechanisms of Echinatin and Licochalcone A

Echinatin and its 1,1-dimethyl-2-propenyl derivative licochalcone A are two chalcones found in the Chinese herbal medicine Gancao. First, their antioxidant mechanisms were investigated using four sets of colorimetric measurements in this study. Three sets were performed in aqueous solution, namely Cu²⁺-reduction, Fe³⁺-reduction, and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide radical (PTIO•)-scavenging measurements, while 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•)-scavenging colorimetric measurements were conducted in methanol solution. The four sets of measurements showed that the radical-scavenging (or metal-reduction) percentages for both echinatin and licochalcone A increased dose-dependently. However, echinatin always gave higher IC₅₀ values than licochalcone A. Further, each product of the reactions of the chalcones with DPPH• was determined using electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS). The UPLC-ESI-Q-TOF-MS/MS determination for echinatin yielded several echinatin–DPPH adduct peaks (m/z 662, 226, and 196) and dimeric echinatin peaks (m/z 538, 417, and 297). Similarly, that for licochalcone A yielded licochalcone A-DPPH adduct peaks (m/z 730, 226, and 196) and dimeric licochalcone A peaks (m/z 674 and 553). Finally, the above experimental data were analyzed using mass spectrometry data analysis techniques, resonance theory, and ionization constant calculations. It was concluded that, (i) in aqueous solution, both echinatin and licochalcone A may undergo an electron transfer (ET) and a proton transfer (PT) to cause the antioxidant action. In addition, (ii) in alcoholic solution, hydrogen atom transfer (HAT) antioxidant mechanisms may also occur for both. HAT may preferably occur at the 4-OH, rather than the 4′-OH. Accordingly, the oxygen at the 4-position participates in radical adduct formation (RAF). Lastly, (iii) the 1,1-dimethyl-2-propenyl substituent improves the antioxidant action in both aqueous and alcoholic solutions.

New chalcone derivative exhibits antiproliferative potential by inducing G2/M cell cycle arrest, mitochondrial-mediated apoptosis and modulation of MAPK signalling pathway

In the present study, we investigated antiproliferative activity of seven newly synthesized chalcone derivatives. Among tested compounds, (2 E)-3-(acridin-9-yl)-1-(2,6-dimethoxyphenyl)prop-2-en-1-one (1C) was the most potent with IC₅₀ = 4.1 μmol/L in human colorectal HCT116 cells and was selected for further studies. Inhibition of cell proliferation was associated with cell cycle arrest in G2/M phase and dysregulation of α, α1 and β5 tubulins. Moreover, 1C caused disruption of the mitochondrial membrane potential and increased number of cells with sub G0/G1 DNA content which is considered as marker of apoptosis. Apoptosis was confirmed by annexin V/PI and AO/PI staining. Furthermore, we found increased concentration of cytochrome c, Smac/Diablo and increased caspase-3 and caspase-9 activity, cleavage of PARP as well as activation of DNA repair mechanisms in 1C-treated HCT116 cancer cells. Moreover this chalcone derivative up-regulated proapoptotic Bax expression and down-regulated antiapoptotic Bcl-2 and Bcl-xL expression. Additionally, 1C treatment led to modulation of MAPKs and Akt signalling pathways. In conclusion, our data showed ability of 1C to suppress cancel cell growth and provide the rationale for further in vivo study.

Chalcone derivatives cause accumulation of colon cancer cells in the G2/M phase and induce apoptosis

AIMS

Chalcones, naturally occurring open-chain polyphenols abundant in plants, have demonstrated antiproliferative activity in several cancer cell lines. In the present study, the potential anticancer activity of two synthetic analogues named Ch1 and Ch2 in colon cancer cell line was investigated.

MAIN METHODS

Antiproliferative activities of both synthetic analogues were assessed by Growth Inhibition Assay (MTT) and xCELLigence cell analysis. Apoptosis was assessed by annexin V/PI staining (early stage) or by DNA fragmentation (final stage). To study the cell death mechanism induced by tested substances, we assessed a series of assays including measurements of the caspase 3 activity, membrane mitochondrial potential (MMP) changes, reactive oxygen species (ROS) production by flow cytometry and expression of important apoptosis-related genes by realtime PCR.

KEY FINDINGS

We found concentration and time-dependent cytotoxicity, inhibition of proliferation of Caco-2 cells after Ch1 and Ch2 treatment in parallel with G2/M phase cell cycle arrest and increased cell proportion in subG0/G1 population with annexin V positivity. We demonstrated that both Ch1 and Ch2 induced caspase-dependent cell death associated with increased ROS production, suppressed Bcl-2 and Bcl-xL and enhanced Bax expression. Treatment of Ch1 also suppressed α-, α1- and β5-tubulins, on the other hand Ch2 only suppressed α-tubulin expression.

SIGNIFICANCE

Presented chalcones induce apoptosis by intrinsic pathways, and therefore may be an interesting strategy for cancer therapy.