RESUMEN
The Myrciaria dubia (Myrtaceae) fruit is traditionally used to treat malnutrition due to its high levels of vitamin C and phenolic compounds. Because of its composition, this plant is very promising in the research of novel natural treatment for pain disorders. This study analyzed the phytochemical profile of M. dubia juice and assessed its antinociceptive and antiedematogenic potential. The phytochemical profile was determined through high-performance liquid chromatography (HPLC), the oral antinociceptive effect of M. dubia 50% juice (Md50) was evaluated by formalin, hot plate and Complete Freund's Adjuvant tests and the antiedematogenic activity by paw edema. HPLC revealed the presence of ascorbic acid, rutin, and ellagic acid as major compounds. Md50 showed an antinociceptive effect in the acute and chronic phases of the formalin test. In the hot plate test, Md50 also induced an antinociceptive effect of 0.5 up to 6 h, showing antinociceptive and antiedematogenic potential without changing the spontaneous locomotion of animals. All protocols were submitted and approved by the Ethics Committee for use of Animals of the Lutheran University of Brazil (protocol No. 2013-30P).
Asunto(s)
Myrtaceae , Extractos Vegetales , Analgésicos , Animales , Frutas/química , Ratones , Fenoles/análisisRESUMEN
Coffee is the main source of chlorogenic acid in the human diet, and it contains several chlorogenic acid isomers, of which the 5-caffeoylquinic acid (5-CQA) is the predominant isomer. Because there are no available data about the action of chlorogenic acids from instant coffee on hepatic glucose-6-phosphatase (G-6-Pase) activity and blood glucose levels, these effects were investigated in rats. The changes on G-6-Pase activity and liver glucose output induced by 5-CQA were also investigated. Instant coffee extract with high chlorogenic acids content (37.8%) inhibited (p < 0.05) the G-6-Pase activity of the hepatocyte microsomal fraction in a dose-dependent way (up to 53), but IV administration of this extract did not change the glycaemia (p > 0.05). Similarly, 5-CQA (1 mM) reduced (p < 0.05) the activity of microsomal G-6-Pase by about 40%, but had no effect (p > 0.05) on glucose output arising from glycogenolysis in liver perfusion. It was concluded that instant coffee extract with high content of chlorogenic acids inhibited hepatic G-6-Pase in vitro, but failed to reduce the glycaemia probably because the coffee chlorogenic acids did not reach enough levels within the hepatocytes to inhibit the G-6-Pase and reduce the liver glucose output.
Asunto(s)
Glucemia/metabolismo , Ácido Clorogénico/farmacología , Café/química , Glucosa-6-Fosfatasa/antagonistas & inhibidores , Microsomas Hepáticos/enzimología , Extractos Vegetales/química , Ácido Quínico/análogos & derivados , Animales , Ácido Clorogénico/química , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Índice Glucémico/efectos de los fármacos , Humanos , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , Microsomas Hepáticos/efectos de los fármacos , Ácido Quínico/química , Ácido Quínico/farmacología , Ratas , Ratas WistarRESUMEN
Dietary isoprenic derivatives such as ß-ionone (ßI) are a promising class of chemopreventive agents. In this study, cellular aspects of ßI protective activities during early hepatocarcinogenesis were evaluated. Male Wistar rats were submitted to "resistant hepatocyte" model and then received daily 16 mg/100 g body weight (b.w.) of ßI (ßI group) or only 0.25 mL/100 g b.w. of corn oil (vehicle, control group [CO]) during 4 wk, specifically during early promotion phase. Compared to controls, ßI inhibited (P < 0.05) the development of persistent preneoplastic lesions (pPNL), considered to be potential hepatocellular carcinoma (HCC) progression sites, and increased remodeling PNL (rPNL) (P < 0.05) that tend to regress to a normal phenotype. Increased ßI hepatic levels (P < 0.05), in the ßI group, were associated with its chemopreventive actions. Compared to control rats, ßI reduced the frequency of both pPNL and rPNL positive for tumor growth factor (TGF)-α (P < 0.05), reduced the frequency of pPNL stained for p65 (nuclear factor-kappaB; NF-κB) (P < 0.05), and reduced the frequency of pPNL positive for cytoplasmic p53 (P < 0.05). Our data demonstrated that ßI targets TGF-α, NF-κB, and p53 in initial phases of hepatocarcinogenesis and specifically inhibits PNL with increased probability to progress to HCC. This isoprenoid may represent a chemopreventive agent of choice for HCC control.
Asunto(s)
Anticarcinógenos/farmacología , Carcinoma Hepatocelular/tratamiento farmacológico , Neoplasias Hepáticas Experimentales/tratamiento farmacológico , Norisoprenoides/farmacología , Animales , Quimioprevención , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , FN-kappa B/antagonistas & inhibidores , FN-kappa B/metabolismo , Ratas , Ratas Wistar , Factor de Crecimiento Transformador alfa/antagonistas & inhibidores , Factor de Crecimiento Transformador alfa/metabolismo , Proteína p53 Supresora de Tumor/antagonistas & inhibidores , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Folic acid (FA) supplementation during carcinogenesis is controversial. Considering the impact of liver cancer as a public health problem and mandatory FA fortification in several countries, the role of FA supplementation in hepatocarcinogenesis should be elucidated. We evaluated FA supplementation during early hepatocarcinogenesis. Rats received daily 0.08 mg (FA8 group) or 0.16 mg (FA16 group) of FA/100 g body weight or water (CO group, controls). After a 2-week treatment, animals were subjected to the "resistant hepatocyte" model of hepatocarcinogenesis (initiation with diethylnitrosamine, selection/promotion with 2-acetylaminofluorene and partial hepatectomy) and euthanized after 8 weeks of treatment. Compared to the CO group, the FA16 group presented: reduced (p < 0.05) number of persistent and increased (p < 0.05) number of remodeling glutathione S-transferase (GST-P) positive preneoplastic lesions (PNL); reduced (p < 0.05) cell proliferation in persistent GST-P positive PNL; decreased (p < 0.05) hepatic DNA damage; and a tendency (p < 0.10) for decreased c-myc expression in microdissected PNL. Regarding all these parameters, no differences (p > 0.05) were observed between CO and FA8 groups. FA-treated groups presented increased hepatic levels of S-adenosylmethionine but only FA16 group presented increased S-adenosylmethionine/S-adenosylhomocysteine ratio. No differences (p > 0.05) were observed between experimental groups regarding apoptosis in persistent and remodeling GST-P positive PNL, and global DNA methylation pattern in microdissected PNL. Altogether, the FA16 group, but not the FA8 group, presented chemopreventive activity. Reversion of PNL phenotype and inhibition of DNA damage and of c-myc expression represent relevant FA cellular and molecular effects.
Asunto(s)
Transformación Celular Neoplásica/efectos de los fármacos , Suplementos Dietéticos , Ácido Fólico/farmacología , Neoplasias Hepáticas Experimentales/prevención & control , Animales , Apoptosis/efectos de los fármacos , Peso Corporal/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/metabolismo , Quimioprevención , Daño del ADN , Metilación de ADN , Expresión Génica , Genes myc , Glutatión Transferasa/metabolismo , Hígado/anatomía & histología , Hígado/metabolismo , Hígado/patología , Neoplasias Hepáticas Experimentales/genética , Neoplasias Hepáticas Experimentales/metabolismo , Masculino , Tamaño de los Órganos/efectos de los fármacos , Lesiones Precancerosas/genética , Lesiones Precancerosas/metabolismo , Lesiones Precancerosas/prevención & control , Ratas , Ratas Wistar , S-Adenosilhomocisteína/metabolismo , S-Adenosilmetionina/metabolismoRESUMEN
Chemopreventive activities of the dietary isoprenoids ß-ionone (ßI) and geraniol (GOH) were evaluated during the promotion phase of hepatocarcinogenesis. Over 5 consecutive weeks, rats received daily 16 mg/100 g body weight (b.w.) of ßI (ßI group), 25 mg/100 g b.w. of GOH (GOH group), or only corn oil (CO group, controls). Compared to the CO group, the following was observed: only the ßI group showed a decrease in the mean number of visible hepatocyte nodules (P<.05); ßI and GOH groups had reduced mean number of persistent preneoplastic lesions (pPNLs) (P<.05), but no differences regarding number of remodeling PNL (rPNLs) were observed; only the ßI group exhibited smaller rPNL size and percentage of liver sections occupied by pPNLs (P<.05), whereas the GOH group displayed a smaller percentage of liver sections occupied by rPNLs (P<.05); a trend was observed in the ßI group, which showed reduced cell proliferation of pPNLs (P<.10), and the GOH group had increased apoptosis in pPNLs and rPNLs (P<.05); only the ßI group displayed reduced total plasma cholesterol concentrations (P<.05) and increased hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase mRNA levels (P<.05); only the GOH group had lower hepatic membrane RhoA protein levels (P<.05); both the ßI- and GOH-treated groups had higher hepatic concentrations of ßI and GOH, respectively (P<.05). Given these data, ßI and GOH show promising chemopreventive effects during promotion of hepatocarcinogenesis by acting through distinct mechanism of actions: ßI may inhibit cell proliferation and modulate HMGCoA reductase, and GOH can induce apoptosis and inhibit RhoA activation.
Asunto(s)
Apoptosis , Proliferación Celular , Hidroximetilglutaril-CoA Reductasas/metabolismo , Norisoprenoides/farmacología , Terpenos/farmacología , Proteína de Unión al GTP rhoA/metabolismo , Monoterpenos Acíclicos , Animales , Western Blotting , Carcinoma Hepatocelular/tratamiento farmacológico , Carcinoma Hepatocelular/metabolismo , Quimioprevención , Colesterol/sangre , Hígado/patología , Neoplasias Hepáticas/tratamiento farmacológico , Neoplasias Hepáticas/metabolismo , Masculino , Lesiones Precancerosas/tratamiento farmacológico , Lesiones Precancerosas/metabolismo , Ratas , Ratas WistarRESUMEN
Leptin, a hormone secreted by the adipocytes, plays a central role in glucose metabolism and the action of insulin. Here we assessed, by means of rat-liver perfusion, the direct influence of physiological (10 ng/ml) and supraphysiological (50 or 100 ng/ml) concentrations of leptin on the suppressive effect of insulin on the glucose production and glycogenolysis stimulated by 8-bromoadenosine-3':5'-monophosphate (8-Br-cAMP). Portal infusion of insulin (20 microU/ml) or leptin (10 ng/ml) reduced (p<0.05) the glucose production and glycogenolysis induced by 8-Br-cAMP (0.3 microM). However, portal infusion of physiological (10 ng/ml) and supraphysiological (50 or 100 ng/ml) concentrations of leptin together with the insulin did not modify the suppressive effect of the latter on the glucose production and glycogenolysis stimulated by 8-Br-cAMP. Moreover, prolonging the period of leptin infusion from 20 to 40 min also failed to influence the liver response to insulin. Thus, we conclude that: (a) leptin, at physiological levels, has a direct and acute effect, inhibiting the glucose production and glycogenolysis stimulated by 8-Br-cAMP; (b) leptin, at either physiological or supraphysiological concentrations, has no short-term influence on the suppressive effect of insulin on glycogen catabolism stimulated by 8-Br-cAMP.
Asunto(s)
GMP Cíclico/análogos & derivados , Glucosa/biosíntesis , Glucogenólisis/efectos de los fármacos , Insulina/farmacología , Leptina/farmacología , Glucógeno Hepático/metabolismo , Hígado/efectos de los fármacos , Animales , GMP Cíclico/farmacología , Hígado/metabolismo , Masculino , Perfusión , Ratas , Ratas WistarRESUMEN
A suplementação com ácido fólico (AF) apresenta efeitos quimiopreventivos, porém, pode aumentar o risco de desenvolvimento e acelerar a progressão do câncer se ocorrer em doses elevadas ou após a ocorrência de lesões pré-neoplásicas (LPN). O AF é essencial na síntese de novo de purinas e timidalato e consequentemente na síntese, replicação e reparo do DNA, proliferação celular e apoptose. Assim, a deficiência pode implicar em danos ao DNA e erros na sua replicação e reparo, processos importantes na carcinogênese, onde as células apresentam taxas de replicação e divisão aceleradas, e é possível que a suplementação module estes processos. Além disso, como AF ocupa uma posição de destaque no metabolismo dos grupamentos metila pode exercer efeitos sobre a hipometilação global do DNA e o aumento da expressão de proto-oncogenes como o c-myc, fenômenos característicos da hepatocarcinogênese. Assim, objetivando-se avaliar os efeitos do AF na promoção da hepatocarcinogênese em ratos Wistar, desenvolveu-se o modelo do /"Hepatócito Resistente/" e administrou-se por entubação gástrica diariamente, durante 5 semanas, o AF (0,16; 0,32; ou 0,64 mg / 100 g de peso / dia) ou água (0,25 mL / 100 g de peso / dia). Então, avaliou-se as LPN hepáticas presentes visíveis à macroscopia e microscopia (GST-P), a proliferação celular (BrdU) e a apoptose (microscopia de fluorescência) no tecido hepático ao redor das LPN e nas LPN persistentes e em remodelação, a intensidade de danos ao DNA (/"Cometa/" alcalino), e o padrão de metilação global (Dot Blot) e a expressão do c-myc (RT-PCR) especificamente em LPN microdissecadas. Apesar de não ter alterado a incidência e multiplicidade das LPN, o tratamento com AF 0,32 mg / 100 g promoveu um aumento na porcentagem de lesões ≥ 1 mm e o com AF 0,64 mg / 100 g a diminuição na porcentagem dessa lesões com relação ao grupo água (p<0,05). De modo semelhante, observou-se na análise das LPN GST-P positivas que o AF 0,32 mg / 100 g promoveu aumento e...
Folic acid (FA) supplementation shows chemopreventive effects, however, it may increase the risk of development and accelerate cancer progression in case of high doses or after preneoplastic lesions (PNL) are established. FA is essential on de novo synthesis of purine and thymidalate and, consequently, on DNA synthesis, replication and repair, cell proliferation and apoptosis. Thus, its deficiency may cause DNA damage and replication and repair mistakes, important processes on carcinogenesis, where cells present high replication rates and accelerated division, and is possible that supplementation modulates these processes. Besides, as FA has a central role on methyl group metabolism, it may have effects on hepatocarcinogenesis peculiar events such as DNA global hypomethylation and on the increased expression of proto-oncogenes like c-myc. Objecting the evaluation of FA effects during hepatocarcinogenesis promotion in Wistar rats, the /"Resistant Hepatocyte/" model was developed and water (0.25 mL / 100 g BW / day) or FA (0.16; 0.32; or 0.64 mg / 100 g BW / day) were supplemented daily by gavage for 5 weeks. Then, hepatic PNL detected by macroscopy and microscopy (GST-P), cell proliferation (BrdU) and apoptosis (fluorescence microscopy) on surrounding tissue, persistent and remodeling PNL, DNA damage (alcaline Comet assay), DNA global methylation pattern (Dot Blot) and c-myc expression (RT-PCR) specifically in microdissected PNL were evaluated. Even though FA treatment was not able to change incidence and multiplicity of PNL, the treatment with 0.32 mg / 100 g of FA increased the percentage of lesions ≥ 1 mm whereas with 0.64 mg / 100 g of FA diminished the percentage of these lesions, compaired to the water group (p<0.05). Similarly, it could be observed in PNL positive GST-P analysis that FA 0.32 mg / 100 g enhanced and FA 0.64 mg / 100 g inhibited the carcinogenic process, although it was not possible to detect significant differences on number, size and
Asunto(s)
Animales , Masculino , Ratas , Ácido Fólico/química , Ácido Fólico/toxicidad , Carcinoma Hepatocelular , Vitaminas en la Dieta , Alimentos , Fenómenos Fisiológicos de la NutriciónRESUMEN
The effects of chlorogenic acid (CA) on hepatic glucose output, blood glucose levels and on glucose tolerance were analysed. Hepatic uptake of CA and its effects on hepatic catabolism of L-alanine and glucose-6-phosphatase (G-6-Pase) activity were also evaluated. CA (1 mM) inhibited about 40% of G-6-Pase activity (p < 0.05) in the microsomal fraction of hepatocytes, but no effect was observed on production of glucose from gluconeogenesis or on L-alanine catabolism, at various concentrations of CA (0.33, 0.5 and 1 mM), in liver perfusion experiments. Since there were indications of a lack of uptake of CA by the liver, it is possible that this compound did not reach sufficiently high intracellular levels to inhibit the target enzyme. Accordingly, intravenous administration of CA also failed to provoke a reduction in blood glucose levels. However, CA did promote a significant reduction (p < 0.05) in the plasma glucose peak at 10 and 15 min during the oral glucose tolerance test, probably by attenuating intestinal glucose absorption, suggesting a possible role for it as a glycaemic index lowering agent and highlighting it as a compound of interest for reducing the risk of developing type 2 diabetes.
Asunto(s)
Glucemia/efectos de los fármacos , Ácido Clorogénico/farmacología , Hígado/metabolismo , Animales , Área Bajo la Curva , Ácido Clorogénico/administración & dosificación , Glucosa/biosíntesis , Prueba de Tolerancia a la Glucosa , Glucosa-6-Fosfatasa/metabolismo , Glicerol/metabolismo , Concentración de Iones de Hidrógeno/efectos de los fármacos , Ácido Láctico/metabolismo , Hígado/efectos de los fármacos , Hígado/enzimología , Masculino , Ácido Pirúvico/metabolismo , Ratas , Ratas Wistar , Urea/metabolismoRESUMEN
The acute effects of physiological levels of leptin (10 ng ml(-1)) and insulin (20 microU ml(-1)) on hepatic gluconeogenesis and ketogenesis were compared. Leptin or insulin alone decreased (p<0.05) the activation of hepatic glucose, L-lactate and urea production from L-alanine. However, the hepatic glucose production was not modified if leptin was combined with insulin. These results indicated that both, i.e. leptin and insulin, could promote a non-additive reduction in the rate of catabolism of L-alanine. However, in contrast with insulin (p<0.05), leptin did not inhibit the activation of hepatic glucose production from pyruvate or glycerol. On the other hand, activation of hepatic production of acetoacetate and beta-hydroxybutyrate from octanoate was not affected by leptin or insulin. Thus, our data demonstrate that the acute effect of leptin on hepatic metabolism was partially similar to insulin (activation of glucose production from L-alanine and activation of acetoacetate or beta-hydroxybutyrate production from octanoate) and partially different from insulin (activation of glucose production from pyruvate or glycerol).