Synthesis of chalcones derived from 1-naphthylacetophenone and evaluation of their cytotoxic and apoptotic effects in acute leukemia cell lines.

Chalcones and their derivatives have been described as promising compounds with antiproliferative activity against leukemic cells. This study aimed to investigate the cytotoxic effect of three synthetic chalcones derived from 1-naphthylacetophenone (F07, F09, and F10) in acute leukemia cell lines (K562 and Jurkat) and examine the mechanisms of cell death induced by these compounds. The three compounds were cytotoxic to K562 and Jurkat cells, with IC50 values ranging from 1.03 to 31.66 µM. Chalcones induced intrinsic and extrinsic apoptosis, resulting in activation of caspase-3 and DNA fragmentation. F07, F09, and F10 were not cytotoxic to human peripheral blood mononuclear cells, did not produce any significant hemolytic activity, and did not affect platelet aggregation after ADP stimulation. These results, combined with calculations of molecular properties, suggest that chalcones F07, F09, and F10 are promising molecules for the development of novel antileukemic drugs.

Synthesis of a novel glibenclamide-pioglitazone hybrid compound and its effects on glucose homeostasis in normal and insulin-resistant rats.

A new library of hybrid compounds that combine the functional parts of glibenclamide and pioglitazone was designed and developed. Compounds were screened for their antihyperglycemic effects on the glucose tolerance curve. This approach provided a single molecule that optimizes the pharmacological activities of two drugs used for the treatment of diabetes mellitus type 2 (DM2) and that have distinct biological activities, potentially minimizing the adverse effects of the original drugs. From a total of 15 compounds, 7 were evaluated in vivo; the compound 2; 4- [2- (2-phenyl-4-oxo-1,3-thiazolidin-3-yl) ethyl] benzene-1-sulfonamide (PTEBS) was selected to study its mechanism of action on glucose and lipid homeostasis in acute and chronic animal models related to DM2. PTEBS reduced glycemia and increased serum insulin in hyperglycemic rats, and elevated in vitro insulin production from isolated pancreatic islets. This compound increased the glycogen content in hepatic and muscular tissue. Moreover, PTEBS stimulated the uptake of glucose in soleus muscle through a signaling pathway similar to that of insulin, stimulating translocation and protein synthesis of glucose transporter 4 (GLUT4). PTEBS was effective in increasing insulin sensitivity in resistance rats by stimulating increased muscle glucose uptake, among other mechanisms. In addition, this compound reduced total triglycerides in a tolerance test to lipids and reduced advanced glycation end products (AGES), without altering lactate dehydrogenase (LDH) activity. Thus, we suggest that PTEBS may have similar effects to the respective prototypes, which may improve the therapeutic efficacy of these molecules and decrease adverse effects in the long-term.

Cell Cycle Arrest and Apoptosis Induction by a New 2,4-Dinitrobenzenesulfonamide Derivative In Acute Leukemia Cells.

BACKGROUND: Current therapies for acute leukemias (ALs) are associated with severe adverse reactions and high relapse rates, which makes the search for new antileukemic agents a necessity. Therefore, the aim of this study was to evaluate the effects of a new sulfonamide, S1, in AL cells K562 and Jurkat. METHODS: The cytotoxic activity of S1 was assessed using MTT method. The involvement of apoptosis in the mechanism of cell death was assessed by flow cytometry and fluorescence microscopy. RESULTS: Our results demonstrated that S1 induced morphological changes suggestive of apoptosis in both K562 and Jurkat cells. Additionally, S1 was not cytotoxic to normal erythrocytes and mononuclear cells and had a highly selective cytotoxicity for AL lineages. The mechanisms of cell death induced by S1 in K562 cells involves cell cycle arrest at G2/M phase and the activation of both extrinsic and intrinsic apoptosis, with an increased FasR and AIF expression and the loss of mitochondrial potential. As for Jurkat, we observed cell cycle blockade at G0/G1 phase, phosphatidylserine exposure and the involvement of intrinsic apoptosis only, with mitochondrial potential loss and a reduced expression of Survivin.  Although sulfonamide S1 did not altered Bcl-2 and Bax expression in AL cell lines, it was able to activate caspase-3 in K562 cells. CONCLUSION: Our results suggest that sulfonamide S1 may be a promising candidate for the development of new drugs for the treatment of ALs.

Molecular events and cytotoxic effects of a novel thiosemicarbazone derivative in human leukemia and lymphoma cell lines.

The present study aimed to investigate the cytotoxic effect of 38 new thiosemicarbazone derivatives on hematological neoplastic cells lines and to select the most effective compounds to investigate the main molecular mechanisms involved in cell death. Cytotoxicity screening on Daudi and Jurkat cells revealed that only compound 1b met the selection criteria; therefore, it was chosen for further investigation. Cell viability of Daudi, Jurkat, Molt-4, Namalwa, K562, and MM.1S cell lines decreased in a concentration- and time-dependent manner after compound1b incubation; nevertheless the compound neither caused significant hemolysis nor reduction in peripheral blood mononuclear cell viability. Although no changes were observed on cell cycle or Ki-67 expression, compound1b induced apoptotic-like cell death with mitochondrial involvement, Bax/Bcl-2 inversion, AIF release, survivin inhibition, and caspase-3 activation in both Daudi and Jurkat cells. Furthermore, the compound reduced NFκB expression in Jurkat cells. In Daudi cells, compound1b also decreased CHOP, Akt, pAkt, and MAPK/ERK2 expression, thereby suggesting modulation of UPR, PI3K/Akt/mTOR, and MAPK/ERK signaling pathways. Finally, the compound was able to reduce the cell viability of samples collected from patients with different lymphoid neoplasms subtypes, showing that thiosemicarbazones derivatives could be used in the development of new drugs with anticancer activity.

Sulfonyl(thio)urea derivative induction of insulin secretion is mediated by potassium, calcium, and sodium channel signal transduction.

AIM: To investigate the mechanism of action of sulfonyl(thio)urea derivative (SD) on glycemia and on insulin secretion in pancreatic islets. METHODS: Wistar rats were divided into hyperglycemic control group, rats received 4 g/kg body weight glucose plus sitagliptin 10 mg/kg (p.o.); hyperglycemic plus SD 10 mg/kg (p.o.); hyperglycemic plus SD plus sitagliptin. Blood was collected before glucose overloading (zero time), and at 15, 30, 60, and 180 min after glucose, from the afore mentioned groups for glycemia and glucagon-like peptide 1 (GLP-1) measurements and intestinal disaccharidases activity. Pancreatic islets were isolated for the calcium influx and insulin secretion in in vitro studies. RESULTS: SD reduced glycemia and increased GLP-1 secretion, while inhibited sucrase and lactase activity. This SD (1.0 and 10.0 µM) stimulated calcium influx in a similar percentile to that of glibenclamide, and in a nonsynergic manner. In addition, the trigger effect of SD on calcium influx was through the K+ -ATP-dependent channels, and partially by activating voltage-dependent K + channels and voltage-dependent calcium channels. Furthermore, SD-stimulated Na + and Ca 2+ entry, induced by the transient receptor potential ankyrin 1 and by modulation of Na + /Ca 2+ exchange. The activation of these pathways by SD culminated in in vitro insulin secretion, reinforcing the critical role of K + -ATP channels in the secretagogue effect of SD. CONCLUSIONS: SD diminish glycemia by inducing GLP-1 secretion and inhibiting disaccharidases. To our knowledge, this is the first report of an insulin secretagogue effect of SD that is mediated by potassium and calcium, as well as sodium, signal transduction.

Synthesis of novel pyrazoline derivatives and the evaluation of death mechanisms involved in their antileukemic activity.

Malignant neoplasms are one of the leading causes of death worldwide and hematologic malignancies, including acute leukemia (AL) is one of the most relevant cancer types. Current available chemotherapeutics are associated with high morbidity and mortality rates, therefore, the search for new molecules with antitumor activity, specific and selective for neoplastic cells, became a great challenge for researchers in the oncology field. As pyrazolines stand out in the literature for their great variety of biological activities, the aim of this study was to synthesize and evaluate the antileukemic activity of five new pyrazoline derivatives. All pyrazolines showed adequate physicochemical properties for a good oral bioavailability. The two unpublished and most effective pyrazoline derivatives have been selected for further experiments. These compounds are highly selective for leukemic cells when compared to non-neoplastic cells and did not cause lysis on human red blood cells. Additionally, selected pyrazolines induced cell cycle arrest at G0/G1 phase and decreased cell proliferation marker KI67. Apoptotic cell death induced by selected pyrazolines was confirmed by morphological analysis, assessment of phosphatidylserine residue exposure and DNA fragmentation. Several factors indicate that both intrinsic and extrinsic apoptosis occurred. These were: increased FasR expression; the predominance of Bax in relation to Bcl-2; the loss of mitochondrial membrane potential; AIF release; decreased expression of survivin (an antiapoptotic protein); and the activation of caspase-3. The selected pyrazolines were also found to be cytotoxic against neoplastic cells collected from the peripheral blood and bone marrow of patients with different subtypes of acute leukemia.

Synthetic thiosemicarbazones as a new class of Mycobacterium tuberculosis protein tyrosine phosphatase A inhibitors.

Mycobacterium tuberculosis secretes two protein tyrosine phosphatases as virulence factors, PtpA and PtpB. Inhibition studies of these enzymes have shown significant attenuation of the M. tuberculosis growth in vivo. As PtpA mediates many effects on the regulation of host signaling ensuring the intracellular survival of the bacterium we report, for the first time, thiosemicarbazones as potential novel class of PtpA inhibitors. Several compounds were synthesized and biologically evaluated, revealing interesting results. Enzyme kinetic assays showed that compounds 5, 9 and 18 are non-competitive inhibitors of PtpA, with Ki values ranging from 1.2 to 5.6 µM. Modeling studies clarified the structure-activity relationships observed in vitro and indicated a possible allosteric binding site in PtpA structure. To the best of our knowledge, this is the first disclosure of potent non-competitive inhibitors of PtpA with great potential for future studies and development of analogues.

Cytotoxic effect of a novel naphthylchalcone against multiple cancer cells focusing on hematologic malignancies.

Chalcones are natural compounds described in the literature by its several properties including cytotoxic activity against several tumor types. Considering that the search for new chemotherapeutic agents is still necessary, the aim of this study was to investigate the cytotoxic mechanisms involved in cell death induced by a synthetic chalcone (A23) on different tumor cells. Chalcone A23 reduced the cell viability of twelve tumor cell lines in a concentration and time dependent manner and it was more cytotoxic against acute leukemia cells. Interestingly, the compound was non cytotoxic to normal cells and non-hemolytic to normal red blood cells. Chalcone A23 decreased the expression of cell proliferation marker KI-67 and blocked the G2/M phase in both K562 and Jurkat cell lines. Cells treated with A23 showed morphological features suggestive of apoptosis, the "latter pattern" in agarose gel, the externalization of phosphatidylserine and caspase-3 and PARP cleavage. Chalcone A23 significantly reduced the mitochondrial membrane potential, decreased the expression of anti-apoptotic proteins Bcl-2 and survivin and increased the expression of pro-apoptotic protein Bax, confirming the involvement of the intrinsic pathway. The increased mitochondrial permeability resulted in the release of AIF, cytochrome c and endonuclease G from the mitochondria to the cytosol. In addition, chalcone A23 increased the expression of FasR and induced Bid cleavage, showing the involvement of the extrinsic pathway. Finally, chalcone A23 seems to have a synergic effect with the chemotherapy drugs cytarabine and vincristine. These results suggest that A23 is an interesting compound with strong and selective anti-tumor activity.

Effects of 1,3,5-triphenyl-4,5-dihydro-1H-pyrazole derivatives on cell-cycle and apoptosis in human acute leukemia cell lines.

Pyrazoline is an important 5-membered nitrogen heterocycle that has been extensively researched. Ten derivatives were synthesized and tested for antileukemic effects on 2 human acute leukemia cell lines, K562 and Jurkat. The most cytotoxic of these derivatives, compound 21, was chosen for investigation of cytotoxicity mechanisms. The results obtained with selectivity calculations revealed that compound 21 is more selective for acute leukemia (K562 and Jurkat cell lines) than for other tumor cell lines. Moreover, compound 21 was not cytotoxic to normal cell lines, indicating a potential use in clinical tests. Compound 21 caused a significant cell cycle arrest in the S-phase in Jurkat cells and increased the proportion of cells in the sub G0/G1 phase in both cell lines. Cells treated with compound 21 demonstrated morphological changes characteristic of apoptosis in the EB/AO assay, confirmed by externalization of phosphatidylserine by the annexin V - fluorescein isothiocyanate method and by DNA fragmentation. An investigation of cytotoxicity mechanisms suggests the involvement of an intrinsic apoptosis pathway due to mitochondrial damage and an increase in the ratio of mitochondrial Bax/Bcl2. Pyrazoline 21 obeyed Lipinski's "rule of five" for drug-likeness. Based on these preliminary results, the antileukemic activity of compound 21 makes it a potential anticancer agent.

Mechanism of Action of Novel Glibenclamide Derivatives on Potassium and Calcium Channels for Insulin Secretion.

Glibenclamide is widely used and remains a cornerstone and an effective antihyperglycemic drug. After the casual discovery of its hypoglycemic potential, this compound was introduced for diabetes treatment. However, the long-term side effects reveal that glibenclamide should be replaced by new molecules able to maintain the health of ß-cells, protecting them from hyperstimulation/hyperexcitability, hyperinsulinemia, functional failure and cell death. The aim of this review was to highlight the main mechanism of action of glibenclamide and the influence of its derivatives, such as acylhydrazones, sulfonamides and sulfonylthioureas on ß-cells potassium and calcium channels for insulin secretion as well as the contribution of these new compounds to restore glucose homeostasis. Furthermore, the role of glibenclamide-based novel structures that promise less excitability of ß-cell in a long-term treatment with effectiveness and safety for diabetes therapy was discussed.

Chalcones to control Alternaria alternata in murcott tangor fruits / Chalconas no controle de Alternaria alternata em frutos de tangor murcote

Alternaria brown spot (ABS), caused by the fungus Alternaria alternata pathotype tangerine, is one of the main phytosanitary problems for mandarin growers. About 15 applications per year of harmful fungicides are required for controlling ABS disease in citrus orchards. As chalcones seem to be less toxic to humans and environment than the commercial fungicides in use, this study initially aimed at synthesizing 137 chalcones through aldolic condensations between benzaldehydes and acetophenones. The resulting chalcones were screened for activity against A. alternata through a fungal growth assay that was carried out in 96-cell polypropylene plates, using the same concentration to all studied substances. The four active chalcones underwent conidia germination and mycelial growth, which confirmed the antifungal activity of the compounds. These chalcones were then poured onto Murcott tangor fruit that had been inoculated with conidia of the fungus. All four chalcones reduced the ABS progress to values significantly smaller (P0.05) than that observed for the control. Statistical calculations showed that the best results were afforded by two compounds, bearing a 2,4,5-trimethoxyphenyl group at position 3 of prop-2-enal and a 3-nitro- or 3-hydroxyphenyl group at position 1 of the aldehyde. Such compounds reduced the incidence of the disease in Murcott tangor fruit to values that did not differ statistically from those obtained with a commercial fungicide.

A mancha marron de Alternaria (MMA), causada pelo fungo Alternaria alternata patótipo tangerina, é um dos maiores problemas fitossanitários dos produtores de tangerina. Aproximadamente 15 aplicações de fungicidas de elevada periculosidade, por ano, são necessárias para o controle de MMA em várias plantações de citros. Como as chalconas parecem menos tóxicas para os seres humanos e para o ambiente que os fungicidas comerciais atualmente em uso, este estudo teve como objetivo inicial sintetizar 137 chalconas através da condensação aldólica de benzaldeídos com acetofenonas. As atividades das chalconas resultantes contra A. alternata foram avaliadas através do emprego de teste de crescimento fúngico em placas de polipropileno com 96 cavidades, empregando a mesma concentração para todas as substâncias estudadas. As quatro chalconas mais ativas foram submetidas a testes de germinação de conídios e de crescimento micelial, que confirmaram as atividades antifúngicas dos compostos selecionados. Estes foram então, aplicados em frutos de tangor Murcote que tinham sido inoculados com conídios do fungo. Todas as quatro chalconas reduziram o progresso de MMA a valores significativamente inferiores (P0.05) ao observado para o controle. Cálculos estatísticos mostraram que os melhores resultados foram obtidos para dois compostos, que tinham um grupo 2,4,5-trimetoxifenil na posição 3 do prop-2-enal e um grupo 3-nitro- ou 3-hidroxifenil na posição 1 do aldeído. Tais compostos reduziram a incidência da doença em frutos de tangor Murcote a valores que não diferiam estatisticamente do obtido com um fungicida comercial.

Investigation of cellular mechanisms involved in apoptosis induced by a synthetic naphthylchalcone in acute leukemia cell lines.

We have previously reported the cytotoxic effects of chalcone A1, derived from 1-naphthaldehyde, in leukemia cell lines. On the basis of these findings, the main aim of this study was to elucidate some of the molecular mechanisms involved in apoptosis induced by chalcone A1 toward K562 and Jurkat cells. In both cell lines, chalcone A1 decreased the mitochondrial membrane potential, increased the expression of Bax proapoptotic protein, and decreased the expression of Bcl-2 antiapoptotic protein (resulting in the inversion of the Bcl-2/Bax ratio), which indicates the involvement of the intrinsic pathway. In addition, chalcone A1 increased the expression of FasR in Jurkat cells, which also indicates the involvement of the extrinsic pathway in this cell line. The results also showed an increased expression of effector caspase-3 and cleaved PARP-1 and a decreased expression of IAP protein survivin, which are consistent with apoptotic cell death. The decreased expression of Ki67 suggests that the mechanism involved in cell death induced by chalcone A1 also involves a decrease in cell proliferation. In ex-vivo experiments, chalcone A1 reduced the cell viability of blast cells collected from eight patients with different types of acute leukemia, confirming the cytotoxicity results found in vitro. The results obtained so far are very promising and further studies need to be carried out so that chalcone A1 can be used as a prototype for the development of new antileukemia agents.

Incretinomimetic and Insulinomimetic Effect of (2E)-N'-(1'-Naphthyl)-3,4,5-Trimethoxybenzohydrazide for Glycemic Homeostasis.

To characterize the role and the mechanism of action of (2E)-N'-(1'-naphthyl)-3,4,5-trimethoxybenzohydrazide (BZD) on incretin secretion, glucose uptake in skeletal muscle and α-glucosidase activity on intestine, targets for glucose homeostasis. It was assayed on glucose tolerance test (GTT) to analyze GLP-1 secretion and the activity of DPP-4 enzyme in vitro. In skeletal muscle, mechanism of action on glucose uptake was carried out by in vitro experiments. The activity of intestinal disaccharidases was performed after in vivo and in vitro experiments. The compound improved the glucose tolerance around 30%, 25%, and 20% at 15, 30, and 60 min, respectively and potentiated the sitagliptin effect, an inhibitor of the enzyme that removes GLP-1, about 50, 45, and 54% at 15, 30, and 60 min, respectively. Additionally, BZD did not modify the activity of DPP-4 enzyme. The acute effect of BZD on glucose uptake is mediated by increasing GLUT4 expression (around 140%) and its translocation to the plasma membrane in soleus muscle. The genomic effect as well as GLUT4 translocation involve the activation of PI-3K and MAPK pathways and require the microtubules integrity to the complete stimulatory effect of this compound on glucose uptake. Beyond, BZD acts in an alternative target to ameliorate glycaemia, intestinal disaccharidases. In a whole, these data point an incretino- and insulinomimetic effect of the compound for glycemic control.

Nanoemulsions containing a synthetic chalcone as an alternative for treating cutaneous leshmaniasis: optimization using a full factorial design.

Nanoemulsions are drug delivery systems that may increase the penetration of lipophilic compounds through the skin, enhancing their topical effect. Chalcones are compounds of low water solubility that have been described as promising molecules for the treatment of cutaneous leishmaniasis (CL). In this context, the aim of this work was to optimize the development of a nanoemulsion containing a synthetic chalcone for CL treatment using a 2(2) full factorial design. The formulations were prepared by spontaneous emulsification and the experimental design studied the influence of two independent variables (type of surfactant - soybean lecithin or sorbitan monooleate and type of co-surfactants - polysorbate 20 or polysorbate 80) on the physicochemical characteristics of the nanoemulsions, as well as on the skin permeation/retention of the synthetic chalcone in porcine skin. In order to evaluate the stability of the systems, the antileishmanial assay was performed against Leishmania amazonensis 24 hours and 60 days after the preparation of the nanoemulsions. The formulation composed of soybean lecithin and polysorbate 20 presented suitable physicochemical characteristics (droplet size 171.9 nm; polydispersity index 0.14; zeta potential -39.43 mV; pH 5.16; and viscosity 2.00 cP), drug content (91.09%) and the highest retention in dermis (3.03 µg·g(-1)) - the main response of interest - confirmed by confocal microscopy. This formulation also presented better stability of leishmanicidal activity in vitro against L. amazonensis amastigote forms (half maximal inhibitory concentration value 0.32±0.05 µM), which confirmed the potential of the nanoemulsion soybean lecithin and polysorbate 20 for CL treatment.

Synthetic compounds from an in house library as inhibitors of falcipain-2 from Plasmodium falciparum.

Falcipain-2 (FP-2) is a key cysteine protease from the malaria parasite Plasmodium falciparum. Many previous studies have identified FP-2 inhibitors; however, none has yet met the criteria for an antimalarial drug candidate. In this work, we assayed an in-house library of non-peptidic organic compounds, including (E)-chalcones, (E)-N'-benzylidene-benzohydrazides and alkyl-esters of gallic acid, and assessed the activity toward FP-2 and their mechanisms of inhibition. The (E)-chalcones 48, 54 and 66 showed the lowest IC50 values (8.5 ± 0.8 µM, 9.5 ± 0.2 µM and 4.9 ± 1.3 µM, respectively). The best inhibitor (compound 66) demonstrated non-competitive inhibition, and using mass spectrometry and fluorescence spectroscopy assays, we suggest a potential allosteric site for the interaction of this compound, located between the catalytic site and the hemoglobin binding arm in FP-2. We combined structural biology tools and mass spectrometry to characterize the inhibition mechanisms of novel compounds targeting FP-2.

Antiherpetic mechanism of a sulfated derivative of Agaricus brasiliensis fruiting bodies polysaccharide.

OBJECTIVE: To study the anti-herpes simplex virus (HSV) activity of a (1→6)-(1→3)-ß-D-glucan isolated from Agaricus brasiliensis fruiting bodies (FR) as well as its chemically sulfated derivative (FR-S). METHODS: The antiherpetic activity and mechanism of action was studied by viral plaque assay applying different methodological strategies. RESULTS: Although FR presented no in vitro antiherpetic action at 1 mg/ml, FR-S displayed promising anti-HSV-1 and anti-HSV-2 activities in both simultaneous and postinfection treatments, resulting in selectivity indices (CC50/EC50) higher than 393. FR-S had no virucidal effect, but significantly suppressed HSV-1 (EC50 = 0.32 µg/ml) and HSV-2 (EC50 = 0.10 µg/ml) adsorption. FR-S was less effective on adsorption inhibition of mutant virus strains devoid of gC (HSV-1 gC⁻39 and HSV-2 gCneg1), indicating a possible interaction with this glycoprotein. The reduction of viral adsorption upon cell pretreatment with FR-S also suggests its interaction with cellular components. FR-S inhibited HSV-1 (EC50 = 8.39 µg/ml) and HSV-2 (EC50 = 2.86 µg/ml) penetration more efficiently than heparin. FR-S reduced HSV-1 and HSV-2 cell-to-cell spread. A synergic effect between FR-S and acyclovir was also detected. CONCLUSIONS: FR-S displays an interesting mechanism of antiviral action and represents a promising candidate for the treatment and/or prevention of herpetic infections, to be used as a single therapeutic agent or in combination with acyclovir.

Novel sulfonyl(thio)urea derivatives act efficiently both as insulin secretagogues and as insulinomimetic compounds.

Glibenclamide is widely used in the management of non-insulin dependent diabetes mellitus, but numerous risks limit its use in therapy. In the search for novel structures that are safer and more efficient than glibenclamide, we obtained new chemical analogs based on bioisosterism, through the treatment of benzenesulfonamide derivatives with isothiocyanates and isocyanates, affording (thio)ureas with good yield. We also verified the hypoglycemic activity, through an in vivo approach. Most of these synthesized compounds improved glucose tolerance, and the mechanism of action of the best compound (7) suggests that its effect is mediated by insulin secretion, while its hypoglycemic action is triggered by glucose uptake involving GLUT4 expression and translocation through PI-3K and PKA activity and active de novo protein synthesis in skeletal muscle. Taking all these factors together, sulfonylthiourea 7 acts as an insulin secretagogue and insulinomimetic agent on glucose homeostasis, and does not exhibit toxicity in acute treatment.

Quinoxaline-substituted chalcones as new inhibitors of breast cancer resistance protein ABCG2: polyspecificity at B-ring position.

A series of chalcones substituted by a quinoxaline unit at the B-ring were synthesized and tested as inhibitors of breast cancer resistance protein-mediated mitoxantrone efflux. These compounds appeared more efficient than analogs containing other B-ring substituents such as 2-naphthyl or 3,4-methylenedioxyphenyl while an intermediate inhibitory activity was obtained with a 1-naphthyl group. In all cases, two or three methoxy groups had to be present on the phenyl A-ring to produce a maximal inhibition. Molecular modeling indicated both electrostatic and steric positive contributions. A higher potency was observed when the 2-naphthyl or 3,4-methylenedioxyphenyl group was shifted to the A-ring and methoxy substituents were shifted to the phenyl B-ring, indicating preferences among polyspecificity of inhibition.

Symmetric bis-chalcones as a new type of breast cancer resistance protein inhibitors with a mechanism different from that of chromones.

Potent ABCG2 inhibitors were recently identified as asymmetric chromones with different types of substituents. We here synthesized symmetric bis-chalcones that were differently substituted and screened for their ability to inhibit mitoxantrone efflux from ABCG2-transfected HEK293 cells. Potent bis-chalcone inhibitors were identified, the efficiency depending on both position of the central ketone groups and the number and positions of lateral methoxy substituents. The best derivative, namely, 1p, was selective for ABCG2 over P-glycoprotein and MRP1, appeared not to be transported by ABCG2, and was at least as active on various drug-selected cancer cells overexpressing ABCG2. Compound 1p stimulated the ABCG2 basal ATPase activity by contrast to a chromone lead that inhibited it, suggesting different mechanisms of interaction. Combination of both types of inhibitors produced synergistic effects, leading to complete inhibition at very low concentrations.

Involvement of extrinsic and intrinsic apoptotic pathways together with endoplasmic reticulum stress in cell death induced by naphthylchalcones in a leukemic cell line: advantages of multi-target action.

Chalcones, naturally occurring open-chain flavonoids abundant in plants, have demonstrated anticancer activity in multiple tumor cells. In a previous work, the potential anticancer activity of three naphthylchalcones named R7, R13 and R15 was shown. In this study, the mechanism of actions of these chalcones was originally shown. The chalcones presented concentration and time-dependent cytotoxicity. To determine the type of cell death induced by chalcones, we assessed a series of assays including measurements of the caspase-8, -9 and -12 activities, expression of important apoptosis-related genes and proteins, changes in the cell calcium concentration and cytochrome c release. The activities of caspase-8, -9 and -12 increased after the treatment of L1210 cells with the three compounds. Chalcones R7 and R13 induced an increase of pro-apoptotic proteins Bax, Bid and Bak (only chalcone R13), as well as a decrease in anti-apoptotic Bcl-2 expression. These chalcones also induced an increase in Fas and a decrease in p21 and p53 expression. Chalcone R15 seems to act by a different mechanism to promote cell death, as it did not change the mitochondrion-related proteins, nor did it induce the cytochrome c release. All compounds induced an increase in cell calcium concentration and an increase in CHOP expression, which together with an increase in caspase-12 activity, suggest that chalcones could induce an endoplasmic reticulum (ER) stress. Taken together, these results suggest that chalcones induce apoptosis by different pathways, being an interesting strategy to suggest for cancer therapy.