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1.
Biol Pharm Bull ; 44(10): 1524-1529, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34602561

RESUMO

Bisphenol A (BPA) has been shown to induce the activation of nuclear estrogen receptor α/ß (ERα/ß) in both in vitro and in vivo settings. We originally obtained a 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), a possible active metabolite of BPA, strongly activating the ERs-mediated transcription in MCF-7 cells with an EC50 of 2.8 nM (i.e., BPA's EC50 = 519 nM). Environmental estrogens can also target G protein-coupled estrogen receptor 1 (GPER1), a membrane-type ER. However, the effects of BPA/MBP on GPER1, have not yet been fully resolved. In this study, we used MCF-7, a ERα/ERß/GPER1-positive human breast cancer cell line, as a model to investigate the effects of the exposure to BPA or MBP. Our results revealed that at concentrations below 1 nM MBP, but not BPA, downregulates the expression of GPER1 mRNA via upregulated ERß, and the MCF-7 cells pre-treated with MBP display resistance to GPER1 agonist G-1-mediated anti-proliferative effects. Because GPER1 can act as a tumor suppressor in several types of cancer including breast cancer, the importance of MBP-mediated decrease in GPER1 expression in breast cancer cells is discussed.

2.
Toxicology ; 447: 152631, 2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33188856

RESUMO

Cadmium (Cd) is recognized as a highly toxic heavy metal for humans in part because it is a multi-organ carcinogen. To clarify the mechanism of Cd carcinogenicity, we have established an experimental system using rat liver TRL1215 cells exposed to 2.5 µM Cd for 10 weeks and then cultured in Cd-free medium for an additional 4 weeks (total 14 weeks). Recently, we demonstrated, by using this experimental system, that 1) Cd stimulates cell invasion by suppression of apolipoprotein E (ApoE) expression, and 2) Cd induces DNA hypermethylation of the regulatory region of the ApoE gene. However, the underlying mechanism(s) as well as other potential genetic participants in the Cd-stimulated invasion are undefined. In the present work, we found that concurrent with enhanced invasion, Cd induced oxidative stress, coupled with the production of oxidative stress-sensitive metallothionein 2A (MT2A), which lead to down-modulation of ten-eleven translocation methylcytosine dioxygenase 1 (TET1: DNA demethylation) in addition to ApoE, without impacting DNA methyltransferases (DNMTs: DNA methylation) levels. Furthermore, the expression of tissue inhibitor of metalloproteinase 2 and 3 (TIMP2 and TIMP3) that are positively regulated by TET1, were decreased by Cd. The genes (ApoE/TET1/TIMP2/TIMP3) suppressed by Cd were further suppressed by hydroquinone (HQ; a reactive oxygen species [ROS] producer), whereas N-acetyl-l-cysteine (NAC; a ROS scavenger) prevented the suppression of their expression by HQ. In addition, NAC reversed their expression suppressed by Cd. Cd-stimulated cell invasion was clearly dampened by NAC in a concentration-dependent manner. Overall these findings suggest that 1) altered TET1 expression and activity together with ApoE are likely involved in the enhanced invasiveness due to Cd exposure, and 2) Cd down-regulation of TET1 likely evokes a reduction in ApoE expression (possible by DNA hypermethylation), and 3) anti-oxidants are effective in abrogation of the enhanced invasiveness that occurs concurrently with Cd-induced malignant transformation.


Assuntos
Cádmio/toxicidade , Dioxigenases/antagonistas & inibidores , Dioxigenases/biossíntese , Fígado/efeitos dos fármacos , Fígado/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Animais , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/fisiologia , Células Cultivadas , Metilação de DNA/efeitos dos fármacos , Metilação de DNA/fisiologia , Relação Dose-Resposta a Droga , Fígado/patologia , Invasividade Neoplásica/patologia , Estresse Oxidativo/fisiologia , Ratos , Ratos Endogâmicos F344
3.
Pharmacy (Basel) ; 8(4)2020 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-33187126

RESUMO

Prognostic prediction has been reported to affect the decision of doctors and non-physician health care providers such as nurses, social workers, pastors, and hospice volunteers on the selection of appropriate medical interventions. This was a case of a 65-year-old woman who presented with a poor oral intake. The patient had a history of sigmoid colon cancer with abdominal wall metastasis and peritoneal dissemination. On the day of admission, nausea, anorexia, and malaise were noted, requiring immediate intervention. The patient's prognosis was predicted using the Palliative Prognostic Index. The pharmacist suggested the use of dexamethasone tablets in order to alleviate the patient's symptoms. Indeed, the administration of dexamethasone alleviated the symptoms of nausea, loss of appetite, and malaise. To the best of our knowledge, this is the first case report to demonstrate that prognosis prediction is important not only for other medical staff but also for pharmacists when deciding the need to initiate a treatment and continue such treatment, and when providing pharmacist interventions.

4.
Biochem Biophys Res Commun ; 531(2): 215-222, 2020 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-32798015

RESUMO

The functional role of fatty acid 2-hydroxylase (FA2H) is controversial in the field of cancer biology due to the dual role of FA2H, particularly related to its interaction with triple-negative breast cancer (TNBC). A previous biochemical- and clinical-focused study suggested that FA2H could dampen TNBC aggressiveness. However, another epidemiological study demonstrated that FA2H expression is associated with shorter disease-free survival in TNBC cases. We reported that FA2H is a peroxisome proliferator-activated receptor α (PPARα)-regulated gene in human breast cancer MDA-MB-231 cells, in vitro experimental models for TNBC analysis. PPARα activation by its ligand reportedly results in an aggressive MDA-MB-231 cell phenotype, as well as estrogen receptor α (ERα)-positive MCF-7 cells. The results of this study show that i) MDA-MB-231 cells express very low levels of FA2H compared to the MCF-7 cells, reflecting a low basal-level PPARα-driven transcriptional activity compared to the MCF-7 cells, and ii) the increased FA2H expression stimulates the MDA-MB-231 and MCF-7 breast cancer cell migration without affecting proliferation. Taken together, our findings indicate that FA2H might be a breast cancer cell migration stimulator, independently of the ERα expression status.


Assuntos
Neoplasias da Mama/patologia , Movimento Celular , Oxigenases de Função Mista/metabolismo , Neoplasias da Mama/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Feminino , Humanos , Oxigenases de Função Mista/genética , Mutação/genética
5.
J Food Sci ; 82(5): 1224-1230, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28346686

RESUMO

The ability of catechins and their related compounds to inhibit breast cancer resistance protein (BCRP) function in Caco-2 cell monolayers was investigated with mitoxantrone as a BCRP substrate. The gallate or pyrogallol moiety on the catechin structure seemed to promote increased cellular accumulation and inhibit efflux transport of mitoxantrone. The ability of gallate catechins such as (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate (ECG) to increase cellular accumulation and inhibit efflux transport of mitoxantrone was greater than that of nongallate catechins. Gallic acid octyl ester (GAO) also increased intracellular mitoxantrone accumulation. Experiments using GAO derivatives indicated that the gallate moiety required the presence of a long carbon chain for BCRP inhibition. Cellular accumulation and reduced efflux transport of mitoxantrone were greater with epigallocatechin 3-(3″-O-butyl) gallate than with EGCG. EGCG inhibition of BCRP seemed to be restricted by hydrophobicity. The co-administration of catechins, particularly EGCG and related compounds, with greater hydrophobicity may increase the therapeutic activities of BCRP substrates such as mitoxantrone.


Assuntos
Analgésicos/metabolismo , Catequina/análogos & derivados , Catequina/farmacologia , Mitoxantrona/metabolismo , Transporte Biológico/efeitos dos fármacos , Células CACO-2 , Humanos , Chá/química
6.
Biochem Biophys Res Commun ; 486(2): 476-480, 2017 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-28315682

RESUMO

Both cholesterol and α-tocopherol are essential lipophilic nutrients for humans and animals. Although cholesterol in excess causes severe problems such as coronary heart disease, it is a necessary component of cell membranes and is the precursor for the biosynthesis of steroid hormones and bile acids. Niemann-Pick C1-like 1 (NPC1L1) is a cholesterol transporter that is highly expressed in the small intestine and liver in humans and plays an important role in cholesterol homeostasis. Cholesterol promotes NPC1L1 endocytosis, which is an early step in cholesterol uptake. Furthermore, α-tocopherol is the most active form of vitamin E, and sufficient amounts of vitamin E are critical for health. It has been reported that NPC1L1 mediates α-tocopherol absorption; however, the mechanisms underlying this process are unknown. In this study, we found that treatment of cells that stably express NPC1L1-GFP with α-tocopherol promotes NPC1L1 endocytosis, and the NPC1L1 inhibitor, ezetimibe, efficiently prevents the α-tocopherol-induced endocytosis of NPC1L1. Cholesterol binding to the N-terminal domain (NTD) of NPC1L1 (NPC1L1-NTD) is essential for NPC1L1-mediated cholesterol absorption. We found that α-tocopherol competitively binds NPC1L1-NTD with cholesterol. Furthermore, when cells stably expressed NPC1L1ΔNTD-GFP, α-tocopherol could not induce the endocytosis of NPC1L1ΔNTD. Taken together, these results demonstrate that NPC1L1 recognizes α-tocopherol via its NTD and mediates α-tocopherol uptake through the same mechanism as cholesterol absorption.


Assuntos
Colesterol/metabolismo , Hepatócitos/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , alfa-Tocoferol/metabolismo , Animais , Anticolesterolemiantes/farmacologia , Ligação Competitiva , Transporte Biológico , Células CACO-2 , Linhagem Celular Tumoral , Colesterol/farmacologia , Endocitose/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/metabolismo , Ezetimiba/farmacologia , Expressão Gênica , Genes Reporter , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Hepatócitos/citologia , Hepatócitos/efeitos dos fármacos , Humanos , Proteínas de Membrana/química , Proteínas de Membrana/genética , Proteínas de Membrana Transportadoras , Plasmídeos/química , Plasmídeos/metabolismo , Ligação Proteica , Domínios Proteicos , Ratos , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética
7.
J Pharm Pharmacol ; 65(7): 1037-43, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23738731

RESUMO

OBJECTIVES: The aim of this study was to investigate the transporter-mediated transport of N-acetyl 5-aminosalicylic acid (Ac-5-ASA) and the effect of quercetin on Ac-5-ASA transport. METHODS: Caco-2 cell monolayers grown in Transwells were used to study the transport of Ac-5-ASA in the absence or presence of quercetin, and apical-to-basolateral and basolateral-to-apical apparent permeability (PappAB and PappBA values, respectively) was determined. The effect of transporter inhibitors, such as MK571, quinidine and mitoxantrone, on the transport of Ac-5-ASA was investigated. KEY FINDINGS: In the absence of transporter mediators, the transport of Ac-5-ASA was much higher in the basolateral-to-apical direction than in the opposite direction. The PappBA/PappAB ratio of Ac-5-ASA was 4.89. Quercetin inhibited the apical efflux of Ac-5-ASA and decreased the PappBA/PappAB ratio to 1.05. Of the transporter inhibitors, MK571 decreased the PappBA/PappAB ratio to 1.07; however, neither quinidine nor mitoxantrone had an effect on Ac-5-ASA transport. CONCLUSIONS: Ac-5-ASA was excreted by multidrug resistance-associated protein 2 from Caco-2 cells, and its transport was inhibited by quercetin. Our findings suggest that dose levels of sulfasalazine or 5-aminosalicylic acid can be decreased by coadministration of quercetin, leading to improved pharmaceutical care for inflammatory bowel diseases.


Assuntos
Ácidos Aminossalicílicos/farmacocinética , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Quercetina/farmacologia , Transporte Biológico , Células CACO-2 , Interações Medicamentosas , Humanos , Mitoxantrona/farmacologia , Propionatos/farmacologia , Quinidina/farmacologia , Quinolinas/farmacologia
8.
J Food Sci ; 77(10): H208-15, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22938538

RESUMO

UNLABELLED: The cellular accumulation of individual catechins was measured as an index of intestinal absorption to clarify the interactions among catechins. The cellular accumulation of (-)-epicatechin (EC) increased in the presence of other catechins. The ability of gallate catechin such as (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate (ECG) to increase the cellular accumulation of EC was greater than that of nongallate catechins. Gallic acid octyl ester (GAO) also increased the cellular accumulation of EC by 426% as compared with that in untreated cells. Conversely, the cellular accumulation of ECG was not influenced by other catechins, but it increased by 54% in the presence of GAO. Experiments using GAO derivatives indicated that the gallate moiety required the presence of a catechol group and a neighboring carbonyl group, whereas the pyrogallol moiety, without a neighboring carbonyl group, required 3 hydroxyl groups to increase the cellular accumulation of EC. Furthermore, gallate esters required long carbon chains to increase the same. The experiment using EGCG, GAO, or their derivatives indicated that the ability of gallate or pyrogallol moiety to increase the cellular accumulation of EC was restricted by their hydrophobicity. These results suggest that the co-administration of foods containing functional materials such as gallate or pyrogallol moieties, increases the intestinal absorption of catechin. PRACTICAL APPLICATION: The cellular accumulation of (-)-epicatechin increased by the gallate or pyrogallol moiety in catechin structure. The interaction among catechins appeared to affect intestinal absorption of catechin. The bioavailability of catechin may be improved by co-administration of functional foods.


Assuntos
Catequina/análogos & derivados , Catequina/farmacocinética , Absorção Intestinal/efeitos dos fármacos , Pirogalol/química , Disponibilidade Biológica , Células CACO-2 , Catequina/química , Alimento Funcional/análise , Humanos , Relação Estrutura-Atividade , Chá/química
9.
J Biomed Biotechnol ; 2009: 467489, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19688110

RESUMO

N-acetyl 5-aminosalicylic acid (5-AcASA) that was intracellularly formed from 5-aminosalicylic acid (5-ASA) at 200 microM was discharged 5.3, 7.1, and 8.1-fold higher into the apical site than into the basolateral site during 1, 2, and 4-hour incubations, respectively, in Caco-2 cells grown in Transwells. The addition of flavonols (100 microM) such as fisetin and quercetin with 5-ASA remarkably decreased the apically directed efflux of 5-AcASA. When 5-ASA (200 microM) was added to Caco-2 cells grown in tissue culture dishes, the formation of 5-AcASA decreased, and, in addition, the formed 5-AcASA was found to be accumulated within the cells in the presence of such flavonols. Thus, the decrease in 5-AcASA efflux by such flavonols was attributed not only to the inhibition of N-acetyl-conjugation of 5-ASA but to the predominant cellular accumulation of 5-AcASA. Various flavonoids also had both of the effects with potencies that depend on their specific structures. The essential structure of flavonoids was an absence of a hydroxyl substitution at the C5 position on the A-ring of flavone structure for the inhibitory effect on the N-acetyl-conjugation of 5-ASA, and a presence of hydroxyl substitutions at the C3' or C4' position on the B-ring of flavone structure for the promoting effect on the cellular accumulation of 5-AcASA. Both the decrease in 5-AcASA apical efflux and the increase in 5-AcASA cellular accumulation were also caused by MK571 and indomethacin, inhibitors of MRPs, but not by quinidine, cyclosporin A, P-glycoprotein inhibitors, and mitoxantrone, a BCRP substrate. These results suggest that certain flavonoids suppress the apical efflux of 5-AcASA possibly by inhibiting MRPs pumps located on apical membranes in Caco-2 cells.


Assuntos
Ácidos Aminossalicílicos/farmacocinética , Flavonoides/farmacologia , Transporte Biológico/efeitos dos fármacos , Células CACO-2 , Linhagem Celular Tumoral , Meios de Cultura , Interações Medicamentosas , Humanos , Mesalamina/farmacocinética , Proteínas Associadas à Resistência a Múltiplos Medicamentos/antagonistas & inibidores , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo
10.
J Pharm Pharmacol ; 60(9): 1189-95, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18718123

RESUMO

The accumulation of (-)-epicatechin (EC), a non-gallate catechin, was significantly lower than that of (-)-epicatechin gallate (ECG), a gallate catechin, in Caco-2 cells. Using Caco-2 cell monolayers cultured in transwells, the transport of catechins in the basolateral-to-apical direction was much higher than that in the apical-to-basolateral direction, suggesting the involvement of an efflux transporter. Moreover, the results suggest that involvement of a transporter in EC efflux is greater than that for ECG. Treatment with transporter inhibitors MK571, quinidine or mitoxantrone, which inhibit MRP2, P-glycoprotein (P-gp) and BCRP, respectively, led to an increase in the accumulation of EC into Caco-2 cells and a decrease in the Papp ratio (Papp B-->A/Papp A-->B) for EC. These transporters seemed to be involved in EC efflux. BCRP was not an efflux transporter for ECG, and the influences of MRP2 and P-gp on ECG efflux were lower than for EC. Thus, efflux transporters appear to be responsible for the difference in cellular accumulation of EC versus ECG, suggesting that the presence or absence of a gallate moiety in the catechin structure influences the transporters.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Catequina/análogos & derivados , Catequina/farmacocinética , Proteínas de Neoplasias/metabolismo , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Transporte Biológico , Células CACO-2 , Catequina/química , Humanos , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo
11.
Nihon Koshu Eisei Zasshi ; 55(4): 238-46, 2008 Apr.
Artigo em Japonês | MEDLINE | ID: mdl-18536338

RESUMO

PURPOSE: The actual state of the accidental ingestion of tobacco products by children and awareness of guardians against its hazards were investigated through a survey among guardians of kindergartenaged children. METHODS: Self-reporting questionnaires were distributed to the guardians of children enrolled in nurseries and kindergartens in cities located in eastern Hiroshima prefecture. Responses of 417 guardians (response rate, 80.5%) were analyzed. The total number of children was reported to be 796 (429 boys, 366 girls, 1 gender unreported) of which 72.2% were under 6 years of age. RESULTS: Based on the survey, 54.4% of fathers and 12.2% of mothers were smokers. Taking into account the presence of other smoking adults such as grandparents, the percentage of families with smokers was 64.3%. Accidental ingestion of tobacco products and the rate including attempted ingestion of tobacco were reported in 15.7% and 28.7% of the families with smokers, respectively. With regard to storage of tobacco and ashtrays, 36.2% of the families with smokers did not store these out of the reach of children, and 7.5% were unaware of the need for a separate storage area. Only 50% of the guardians were aware of the hazards of nicotine exudates. 84.0% of the families with smokers agreed that children should be protected from passive smoking for maintaining good health and growth. However, only 25.0% of the families with smokers had a guardians who actually protected children from passive smoking. CONCLUSION: The results of the survey indicated that 64.3% of families with preschool-age children had smoking members. Tobacco products were not appropriately stored out of the reach of children. Moreover, several cases of accidental ingestion of tobacco products by children had occurred in families with smokers. Furthermore, it was indicated that many children were exposed to passive smoking, although most guardians were aware of its risks.


Assuntos
Família/psicologia , Tabaco/envenenamento , Pré-Escolar , Feminino , Humanos , Masculino , Fumar , Poluição por Fumaça de Tabaco
12.
Toxicol In Vitro ; 21(5): 827-34, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17408918

RESUMO

The previous studies from our laboratory reported that benzo(a)pyrene (Bap) influenced efflux transport of rhodamine 123 (Rho-123) by induction of P-glycoprotein (P-gp) in Caco-2 cells. The present study investigated whether induction of P-gp and the enhanced efflux transport of Rho-123 were caused by benzo(e)pyrene (Bep), which has a structure similar to Bap, but is not a carcinogenic compound. In Caco-2 monolayer exposed to 50 microM Bep for 72 h, the ratio of the apparent permeability coefficient (P(app)) of Rho-123 efflux increased significantly compared to that of the control monolayer. Similarly, a significant increase in expression of MDR1 mRNA and of P-gp at the protein level were detected by RT-PCR and by Western blot analysis, respectively, in Caco-2 cells exposed to Bep, compared to that of the control. Caco-2 cells exposed to Bep showed oxidative stress that was detected by fluorescence microscopy using aminophenyl fluorescein. However, the oxidative stress was weaker compared with that of Bap. The cellular GSH content was decreased to 80% or 59% of control cells, respectively, in Caco-2 cells exposed to either Bep or Bap. Our results further show that Bep or Bap-induced P-gp in Caco-2 cells might have been the result of oxidative stress rather than DNA damage.


Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/fisiologia , Benzo(a)pireno/toxicidade , Benzopirenos/toxicidade , Carcinógenos/toxicidade , Transporte Biológico Ativo/efeitos dos fármacos , Western Blotting , Células CACO-2 , Sobrevivência Celular/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Glutationa/metabolismo , Humanos , Microscopia de Fluorescência , Estresse Oxidativo/efeitos dos fármacos , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Rodamina 123
13.
Toxicology ; 223(1-2): 156-65, 2006 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-16647797

RESUMO

The main exposure pathway of benzo[a]pyrene (Bap) for humans is considered to be via the daily diet. The purpose of this study was to investigate the effect of BaP on the intestinal transport of chemicals mediated by P-glycoprotein (P-gp). The intestinal epithelial membrane transport of rhodamine-123 (Rho-123), a substrate of P-gp, was examined using a monolayer of the human Caco-2 cell line grown in transwells. In the monolayer exposed to Bap for 72 h before transport experiments, the ratio of the apparent permeability coefficients (P(app)) of Rho-123 efflux increased compared to that of the control. The permeability of rhodamine-B (Rho-B), not a substrate of P-gp, showed no difference between the monolayers. Treatment with quinidine or cyclosporine A, which are P-gp inhibitors, decreased the P(app) of Rho-123 to the same degree in both monolayers. The transport of Rho-123 was not influenced by the presence of Bap. Thus, Bap seemed not to act directly on the efflux activity of P-gp and be a binding site competitor of Rho-123. In the Caco-2 cells that enhanced the efflux of Rho-123 by the treatment with Bap, an increase in mRNA expression of MDR 1 (P-gp) was confirmed compared to that of control by RT-PCR. Furthermore, Western blot analysis using a monoclonal antibody, C219, demonstrated the increase of P-gp in Caco-2 cells exposed to Bap, compared with controls. It was inferred that Bap exposure induced the expression of P-gp, which led to the observed increase in efflux transport of Rho-123. The possibility was suggested that Bap might affect the disposition of medicines by increasing P-gp expression.


Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/biossíntese , Benzo(a)pireno/toxicidade , Permeabilidade da Membrana Celular/efeitos dos fármacos , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/antagonistas & inibidores , Western Blotting , Células CACO-2 , Humanos , Rodamina 123/farmacocinética , Fatores de Tempo
14.
Biol Pharm Bull ; 28(8): 1509-13, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16079503

RESUMO

Flavonoids including tea catechins and gallic acid esters were characterized for their ability to inhibit o-methyltranslation of protocatechuic acid (PCA) to form vanillic acid (VA) in rat liver cytosolic preparations and cultured hepatocytes. Flavonols and flavones exhibited different behaviors in inhibiting the formation of VA between the cell-free enzymatic preparations and the intact cells. The underlying mechanism of the inhibitory effects of flavonols and flavones on PCA o-methylation in cultured hepatocytes may not be due to the inhibition of the enzyme activity of catechol o-methyl transferase (COMT). Catechin gallates inhibited PCA o-methylation in liver cytosolic preparations with markedly higher potency than other flavonoids. As compared with catechin gallates, ungallated catechins had two to three orders of magnitude lower efficiency in inhibiting cytosolic PCA o-methylation. Gallic acid esters inhibited cytosolic PCA o-methylation with strong potency almost equal to that of catechin gallates. These results suggest that the COMT-inhibitory activity of catechin gallates is derived from the presence of the galloyl moiety at the C3 position in the C-ring. Catechin gallates and gallic acid esters inhibited PCA o-methylation in cultured hepatocytes with two orders of magnitude lower efficacy than that in cytosolic preparations. The inhibitory effects of catechin gallates and gallic acid esters on cellular PCA o-methylation appear to be due to the direct inhibition of COMT activity.


Assuntos
Catequina/análogos & derivados , Citosol/efeitos dos fármacos , Hepatócitos/efeitos dos fármacos , Hidroxibenzoatos/metabolismo , Fígado/efeitos dos fármacos , Animais , Catequina/farmacologia , Catecol O-Metiltransferase/metabolismo , Células Cultivadas , Cromatografia Líquida de Alta Pressão , Citosol/metabolismo , Hepatócitos/metabolismo , Fígado/metabolismo , Masculino , Metilação , Ratos , Ratos Wistar
15.
Free Radic Res ; 39(3): 237-44, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15788228

RESUMO

Flavonoids were examined for synergistic effects with ascorbate on enhancement of DNA degradation induced by a bleomycin(BLM)-Fe complex. The synergistic effects of flavonoids and ascorbate on DNA degradation induced by the BLM-Fe complex were observed to be greater with flavonoids such as isorhamnetin, kaempferol and morin, which accelerated oxidation more markedly in the presence, than in the absence of BLM. Conversely, myricetin and fisetin, which showed oxidation barely accelerated by the addition of BLM, inhibited DNA degradation promoted by ascorbate. Consequently, there was a good correlation between oxidation of flavonoids accelerated by BLM and the extent of DNA degradation promoted synergistically with ascorbate. Our previous studies indicated that oxidation of flavonoids accelerated by BLM and DNA degradation promoted by flavonoids were not correlated with Fe(III)-reducing activity of flavonoids. Those results suggest that Fe(III)-reducing activity of flavonoids is not the only factor determining DNA degradation-promoting activity induced by the BLM-Fe complex. On the other hand, in a Fenton reaction, degradation of 2-deoxy-d-ribose promoted by flavonoids was correlated to the Fe(III)-reducing activity of flavonoids. However, there was not a synergistic interaction between flavonoids and ascorbate in the degradation of 2-deoxy-d-ribose. Therefore, it is suggested that the synergistic DNA degradation caused by flavonoids and ascorbate in the BLM-Fe redox cycle arose from the difference in the reductive processes in which flavonoids and ascorbate mainly act.


Assuntos
Ácido Ascórbico/farmacologia , Bleomicina/farmacologia , DNA/metabolismo , Sinergismo Farmacológico , Compostos Ferrosos/farmacologia , Flavonoides/farmacologia , Animais , Antibióticos Antineoplásicos/farmacologia , Desoxirribose/metabolismo , Oxirredução , Salmão
16.
Biol Pharm Bull ; 27(9): 1455-8, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15340238

RESUMO

5-Aminosalicylic acid (5-ASA) is an effective drug for the treatment of ulcerative colitis and Crohn's disease. A large group of flavonoids was investigated for their inhibitory effects on the N-acetyl-conjugation of 5-ASA in rat hepatocytes and subcellular preparations. When added to cultured hepatocytes, some flavonoids inhibited the production of N-acetyl-5-aminosalicylic acid (5-AcASA) with potencies that depended on the specific structure of flavonoids. Among the flavonols, quercetin, kaempferol and galangin had inhibitory activity with a tendency to be more effective at increasing the number of hydroxyl substitutions in the B-ring. Flavones such as luteolin, apigenin and chrysin were as effective as the corresponding three flavonols above. 7,3',4'-OH flavone was more effective than other simple flavones such as 7-, 5-, 3-, 7,3-, 7,4'- and 3',4'-OH flavones. Isoflavones were relatively weak inhibitors. Taxifolin and catechins had little or no inhibitory effect. These data suggest that the presence of C7 hydroxyl substitution on the A-ring and the catechol group on the B-ring in the flavone structure is required for effective inhibitory activity. The inhibitory effect of flavonoids on N-acetyl-conjugation of 5-ASA was also examined by incubating 5-ASA with isolated liver cytosolic preparations. The active flavonoids in the cells inhibited the N-acetylation of 5-ASA in the cell-free enzymatic preparations with a potency comparable to that for cultured rat hepatocytes.


Assuntos
Flavonoides/farmacologia , Hepatócitos/metabolismo , Mesalamina/metabolismo , Acetilação/efeitos dos fármacos , Animais , Células Cultivadas , Masculino , Ratos , Ratos Wistar
17.
Biol Pharm Bull ; 27(5): 714-7, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15133252

RESUMO

A large group of flavonoids was investigated for inhibitory effects on sulfo- and glucurono-conjugation of acetaminophen when added to rat cultured hepatocytes and liver subcellular preparations. The flavonoids inhibited the production of both sulfate and glucuronide conjugates in the cultured cells, with potencies that depended on the specific flavonoid. Among the flavonols, quercetin, kaempferol and galangin were much more effective than myricetin and morin. Flavones including luteolin, apigenin and chrysin were as effective as the corresponding three flavonols above. The inhibition of conjugation by other simple flavones such as 3-, 5-, 7- and 3',4'-OH flavones, and by catechins such as epicatechin and epigallocatechin, was very weak. These data suggest that the presence of both C5 and 7 hydroxyl substitutions on the A-ring in the flavone structure is required for effective inhibitory activity. The effect of flavonoids on sulfo- and glucurono-conjugation was also examined by incubating acetaminophen with isolated liver cytosolic and microsomal preparations, respectively. The active flavonoids in the cells remarkably inhibited the sulfation, but not glucuronidation, in cell-free enzymatic preparations in vitro. The mechanism of inhibition of conjugation by flavonoids in cultured hepatocytes is not likely to depend on the direct inhibition of sulfo- and glucurono-transferase activity by flavonoids.


Assuntos
Acetaminofen/metabolismo , Flavonoides/farmacologia , Hepatócitos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Acetaminofen/antagonistas & inibidores , Animais , Células Cultivadas , Flavonoides/química , Glucuronídeos/antagonistas & inibidores , Glucuronídeos/metabolismo , Hepatócitos/metabolismo , Fígado/metabolismo , Fígado/ultraestrutura , Masculino , Ratos , Ratos Wistar , Frações Subcelulares/efeitos dos fármacos , Frações Subcelulares/metabolismo , Sulfetos/antagonistas & inibidores , Sulfetos/metabolismo
18.
J Biochem Mol Toxicol ; 17(4): 239-47, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-12898648

RESUMO

Previous studies examined the bioavailability and first-pass biotransformation of 3-hydroxy[(3)H]benzo[a]pyrene ([(3)H]-3-OHBaP) in an isolated perfused catfish intestinal model. This work showed that 3-OHBaP, or a metabolite formed in intestine, bound covalently to blood protein. In this study, the blood adducts were characterized in vitro by incubating bovine ferric hemoglobin or albumin with [(3)H]-3OHBaP under various conditions. Incubation of 2 microM [(3)H]-3-OHBaP with hemoglobin for 1 h resulted in 7.49 pmol bound/mg protein, while albumin binding was 1.37 pmol/mg protein. Mild acid hydrolysis released only 5% of the radioactivity from 3-OHBaP-hemoglobin adducts. After gel filtration, the 3-OHBaP-hemoglobin adducts were examined by HPLC analysis. A single peak of radioactivity was detected at the same retention time as the heme component of hemoglobin. Unbound 3-OHBaP was oxidized to BaP-3,6-dione during incubation with ferric hemoglobin. Treatment of hemoglobin with ascorbic acid decreased the formation of hemoglobin adducts by 33%, while hydrogen peroxide treatment increased adduct formation by 44%. Incubation of [(3)H]-BaP-3-beta-D-glucuronide (BaP-3G) with hemoglobin and beta-glucuronidase resulted in greater binding to hemoglobin than incubation with [(3)H]-3-OHBaP alone. The hemoglobin adduct obtained from [(3)H]-BaP-3G also co-migrated with heme. These results indicate that an oxidative process is involved in formation of the heme adduct and that 3-OHBaP or BaP-3G might be a precursor of the bound metabolite.


Assuntos
Benzopirenos/metabolismo , Hemoglobinas/metabolismo , Albumina Sérica/metabolismo , Animais , Ácido Ascórbico/química , Ácido Ascórbico/metabolismo , Benzopirenos/química , Bovinos , Cromatografia Líquida de Alta Pressão , Glucuronidase/metabolismo , Hemoglobinas/química , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Ligação Proteica , Albumina Sérica/química , Fatores de Tempo , Trítio
19.
Biol Pharm Bull ; 26(8): 1108-14, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12913260

RESUMO

Sixteen flavonoids including quercetin and kaempferol and their relatives were examined for their ability to promote DNA degradation induced by the bleomycin (BLM)-Fe complex. Three hydroxyl groups in the flavonoidal nucleus were proposed as a crucial structural requirement for effectively promoting DNA degradation: 1). the C7-hydroxyl substitution in the A-ring; 2). the C4'-hydroxyl substitution in the B-ring; and 3). the C3-hydroxyl substitution in the C-ring. Flavonoids, which lack even one of these hydroxyl substitutions, showed remarkably diminished activity. There was a good correlation (r=0.920, p<0.001) between activity to promote DNA degradation and oxidizability, which was measured following the Fe(III)-induced oxidation of flavonoids themselves, among the 16 flavonoids. The oxidizability of flavonoids which have the crucial hydroxyl substitutions, was remarkably enhanced in the presence compared with the absence of BLM. On the other hand, the extent of oxidation of flavonoids lacking these substitutions was enhanced little or not at all by BLM. No correlation between the Fe(III)-reducing activity and DNA degradation-promoting activity was found among flavonoids satisfying the crucial structural requirements. Furthermore, the correlation between the extent of oxidation of flavonoids and the Fe(III)-reducing activity was not confirmed among these flavonoids. Therefore, it was suggested that Fe(III)-reducing activity was not the only factor determining DNA degradation-promoting activity in flavonoids having the three hydroxyl groups necessary for effectively promoting DNA degradation induced by BLM-Fe complex.


Assuntos
Bleomicina/farmacologia , DNA/metabolismo , Compostos Ferrosos/farmacologia , Flavonoides/metabolismo , Animais , Relação Dose-Resposta a Droga , Flavonoides/química , Oxirredução , Salmão , Relação Estrutura-Atividade
20.
Biol Pharm Bull ; 26(8): 1120-4, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12913262

RESUMO

Glucurono- and sulfo-conjugation of kaempferol in rat liver preparations and cultured hepatocytes were studied using high-performance liquid chromatography (HPLC) with two distinctly different elution solvents. Kaempferol glucuronides and sulfates were produced by treating kaempferol with microsomes plus UDPGA or with cytosol plus PAPS, respectively. HPLC analysis of the conjugates revealed one major and three minor glucuronides with solvent A and one sulfate with solvent B. Kaempferol metabolites produced by cultured hepatocytes also consisted of four glucuronides and one minor sulfate, all of which corresponded to their respective in vitro-produced conjugates in the liver subcellular preparations. The relative proportion of kaempferol sulfate accounted for about 9% of the total conjugates in the cultured hepatocytes. The kinetic data on glucurono- and sulfo-conjugation of kaempferol by the liver subcellular preparations correlated well with the preferential production of kaempferol glucuronides in the cultured hepatocytes. Glucurono- and sulfo-conjugation of 3-, 5- and 7-OH flavones in the liver subcellular preparations were also kinetically characterized. 7-OH flavone was predominantly conjugated to form a glucuronide compared to 3- and 5-OH flavones. These data suggest that glucuronidation at the 7-OH position on the A-ring is a major metabolic pathway of kaempferol in hepatic cells.


Assuntos
Glucuronídeos/metabolismo , Hepatócitos/metabolismo , Quempferóis/metabolismo , Sulfetos/metabolismo , Animais , Biotransformação , Células Cultivadas , Quempferóis/química , Fígado/metabolismo , Masculino , Ratos , Ratos Wistar , Frações Subcelulares/metabolismo
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