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1.
Green tea, one of the most popular beverages consumed in Asian countries, has been reported to possess anticarcinogenic and antimutagenic properties. The aim in this study is to test the radical scavenging effect of catechins and caffeine, which were major components of green tea, and if they really prevent oxygen radical-induced mutagenesis. We used TA102 strain of Salmonella typhimurium which is sensitive to hydroxyl radical in the Ames mutation assay. We found that caffeine did not show any effects on mutagenesis in this system, but catechin significantly reduced mutagenesis or genotoxicity caused by hydroxyl radical. This radical-scavenging action of catechins may indeed contribute to the anticarcinogenic activity of green tea as has been proposed.  相似文献   

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3.
Pleurotus cornucopiae (PC) mushroom with a brilliant yellow pileus is found in the field and known in Japan as Tamogi dake mushroom. The purpose of this paper is to investigate the mechanism of the antimutagenic effect of PC mushroom using both the Ames test and Comet assay. We have found a strong inhibitory effect of both aqueous and organic PC extracts on the mutagenicity elicited by benzo[a]pyrene (B[a]P). This inhibition was dose-dependent in reaction mixtures containing cytosolic and microsomal fractions (S-9) from untreated rat liver as well as in those containing S-9 from aryl hydrocarbon receptor (Ah) ligand of Sudan III-treated rats. Sudan III was a potent inducer of cytochrome P450 1A (CYP1A) activity. We treated rats with Sudan III to enhance the metabolic activation of B[a]P by the S-9 fraction. To explain whether this antimutagenicity was due to the inhibition of CYP1A activity that metabolically activates B[a]P, we tested the effects of the extracts on activities of CYP1A1 and CYP1A2, represented by ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-demethylase (MROD), respectively. Both aqueous and organic extracts inhibited EROD activity at all dose levels, while the inhibitory effect was only observed at high doses with regard to MROD activity. Furthermore, pre-treatment of Chinese hamster V79cells with PC extracts significantly reduced H2O2-induced-DNA damage, indicating that PC extracts provide a protective effect against oxidative DNA damage. These results indicate that whole-mushroom extracts contain compounds that may inhibit the metabolic activation of B[a]P by CYP1A1 as well as prevent oxidative DNA damage.  相似文献   

4.
Five commonly used human cytochrome P450 (CYP) inhibitors were examined for their effects on coumarin 7-hydroxylase (CYP2A) activity in pig liver microsomes. The K(m) and V(max) values for coumarin 7-hydroxylation in pig liver microsomes were estimated to be 1 μm and 0.26 nmol·mg/min, respectively. The following human CYP inhibitors caused little or no inhibition of CYP2A as defined by a K(i) > 200 μm: quinidine (CYP2D6), troleandomycin (CYP3A4), and sulfaphenazole (CYP2C9). The other two human CYP inhibitors were classified as strong inhibitors of CYP2A: 8-methoxypsoralen (CYP2A6) and α-naphthoflavone (CYP1A1/2). In the absence of a preincubation period, 8-MOP inhibited the 7-hydroxylation of coumarin with a K(i) value of 1.1 μm, which decreased to 0.1 μm when 8-MOP was preincubated with pig liver microsomes for 3 min. α-Naphthoflavone inhibited the 7-hydroxylation of coumarin with a K(i) value of 32 μm, which did not increase ability to inhibitor CYP2A when α-naphthoflavone was preincubated with pig liver microsomes for 3 min. These results of this study suggest that 8-MOP is a potent, mechanism-based inhibitor of pig CYP2A activity in pig liver microsomes.  相似文献   

5.
The inhibitory effects of fluoroquinolones on the enzyme activity, protein levels and mRNA expression of liver cytochrome P450 (CYP) 1A and 3A were investigated in male broiler chicks. Enrofloxacin (20 mg/kg), sarafloxacin (8 mg/kg) and marbofloxacin (5.5 mg/kg) were administrated in drinking water for 7 consecutive days. A cocktail of the probe drugs caffeine and dapsone was used to determine CYP1A and 3A activity. Western blot analysis and real-time PCR were used to determine the effects on protein levels of CYP1A and 3A, and on CYP1A4, 1A5, 3A37 mRNA levels. Enrofloxacin increased the half-life of elimination for both caffeine and dapsone, and decreased expression of CYP1A and 3A protein. Marbofloxacin decreased the metabolism of caffeine and expression of CYP1A protein. However, no change in mRNA expression was observed for any treatment group. This suggested that high doses of enrofloxacin and marbofloxacin, but not sarafloxacin, inhibit CYP in chick liver raising the possibility of drug-drug interaction when using these compounds.  相似文献   

6.
The objective of this study was to determine the activity of steroid‐ and eicosanoid‐metabolizing enzymes in horses with varying BCSs. The BCSs of twenty non‐pregnant, anoestrous mares were determined prior to euthanasia, and tissue samples were collected from the liver, kidney, adrenal gland, ovary and endometrium. Cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A) and uridine 5′‐diphospho‐glucuronosyltransferase (UGT) activities were determined using luminogenic substrates. The MIXED procedure of SAS was used to test the effect of BCS on enzyme activity and differences between tissues. Activity of CYP1A in adrenals was increased (p ≤ .05) in BCS 5 versus BCSs 4 and 6. Activity of CYP1A in the liver was increased (p = .05) in BCS 4 versus BCSs 5 and 6. Activity of CYP1A was 100‐fold greater (p < .0001) in the liver than in the adrenal, ovary and kidney. Activity of CYP2C was 100‐fold greater (p < .0001) in the liver than in the adrenal, ovary and endometrium. Activity of CYP3A was only detectable in the liver. Activity of UGT in the kidney was decreased (p = .02) in BCS 4 versus BCSs 5 and 6. Activity of UGT was threefold greater (p < .0001) in the liver than in the kidney, whereas activity of UGT was ninefold greater (p < .0001) in the kidney than in the ovary and endometrium. In general, BCS did not alter the activity of steroid‐ and eicosanoid‐metabolizing enzymes in horses. However, tissue differences in these enzymes indicated abundant hepatic metabolism in horses, which is similar to other livestock species.  相似文献   

7.
Green tea (Camellia sinensis) is a popular herbal plant with abundant health benefits, and thus, it has been used as a potent antioxidant for a long time. Based on the available literature, the diversity and the availability of multifunctional compounds in green tea offer its noteworthy potential against many diseases such as liver and heart diseases, inflammatory conditions and different metabolic syndromes. Owing to its bioactive constituents including caffeine, amino acids, l -theanine, polyphenols/flavonoids and carbohydrates among other potent molecules, green tea has many pharmacological and physiological effects. The effects of green tea include anti-oxidative, anti-inflammatory, anti-arthritic, anti-stress, hypolipidaemic, hypocholesterolaemic, skin/collagen protective, hepatoprotective, anti-diabetic, anti-microbial, anti-infective, anti-parasitic, anti-cancerous, inhibition of tumorigenesis and angiogenesis, anti-mutagenic, and memory and bone health-improving activities. Apart from its utilization in humans, green tea has also played a significant role in livestock production such as in dairy, piggery, goatry and poultry industries. Supplementation of animal feeds with green tea and its products is in line with the modern concepts of organic livestock production. Hence, incorporating green tea or green tea by-products into the diet of poultry and other livestock can enhance the value of the products obtained from these animals. Herein, an effort is made to extend the knowledge on the importance and useful applications of green tea and its important constituents in animal production including poultry. This review will be a guideline for researchers and entrepreneurs who want to explore the utilization of feeds supplemented with green tea and green tea by-products for the enhancement of livestock production.  相似文献   

8.
Supplementation of pigs with vitamin E, the most important lipid-soluble antioxidant, has been shown to improve meat quality and animal health. Previous studies in cultured cells and laboratory animals indicate synergistic effects between polyphenols and vitamin E. The present feeding trial was undertaken to investigate the effects of dietary green tea polyphenols (GTP) on vitamin E status, antioxidative capacity and parameters of meat quality in growing pigs. Eighteen castrated, crossbred, male pigs received a flavonoid-poor diet based on corn starch, caseinate and rapeseed oil with a total vitamin E content of 17 IU/kg diet over a period of 5 weeks. This basal diet was supplemented with green tea extract to provide daily doses of 0 (control), 10 and 100 mg GTP/kg body weight. Dietary supplementation of growing pigs with GTP did not affect serum, liver, lung and muscle vitamin E (α- and γ-tocopherol) concentrations, plasma antioxidant capacity (ferric reducing ability of plasma, trolox equivalent antioxidant capacity) or parameters of meat quality including meat temperature, pH, conductivity, colour and drip loss. In conclusion, supplementation of pig diets with green tea catechins is not associated with improved antioxidant status and meat quality under practice-oriented conditions.  相似文献   

9.
Our previous studies demonstrated that prenatal diethylstilbestrol (DES) treatment disrupts steroidogenesis but induces high-level expression of androgen receptor (AR) mRNA to inhibit the disruption of spermatogenesis. This study examined which prenatal DES treatment influenced hepatic microsomal enzymes, CYP3A1, CYP2B1/2, CYP2C11, UGT2B1 (UDP-glucuronosyltransferase 2B1), and IGF-1 (insulin-like growth factor-1), in male rat offspring. DES treatment decreased the mRNA expression levels of CYP3A1 and CYP2B1/2, but did not alter the expression of CYP2C11. At 6 weeks, DES treatment increasd the mRNA expression levels of UGT2B1 and IGF-1. These results suggest that prenatal DES treatment alters two hepatic enzymes (CYP3A1 and CYP2B1/2) and IGF-1 mRNA expression levels to counteract the low level of testosterone, but this disrupted UGT2B1 mRNA expression reduces the testosterone level.  相似文献   

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11.
本文旨在探讨苜蓿皂苷对高脂血症大鼠胆固醇代谢及肝脏组织中胆固醇7α-羟化酶( CYP7 A1)、低密度脂蛋白受体(LDL-R)基因表达的影响.取雄性健康SD大鼠40只,随机分为4组,分别为:正常对照组、高脂模型组、苜蓿皂苷预防组和苜蓿皂苷治疗组,每组10只.正常对照组饲喂基础饲粮,其余3组均饲喂高脂饲粮,其中苜蓿皂苷预防组从第1周开始灌胃240 mg/kg苜蓿皂苷,苜蓿皂苷治疗组从第5周开始灌胃240 mg/kg苜蓿皂苷,试验期共8周.测定试验大鼠体重、肝脏系数、血脂水平和肝脏病理变化情况,并采用酶联免疫法和实时荧光定量PCR技术分别检测大鼠肝脏CYP7A1和LDL-R的蛋白和mRNA表达结果.结果表明:1)和高脂模型组相比,苜蓿皂苷极显著降低预防组大鼠体重及预防组和治疗组血清总胆固醇及低密度脂蛋白胆固醇含量(P＜0.01),同时改善肝脏脂化程度.2)苜蓿皂苷预防组和治疗组CYP7 A1和LDL-R的蛋白和mRNA表达量极显著高于高脂模型组(P＜0.01).结果提示,苜蓿皂苷通过促进肝脏CYP7A1和LDL-R的表达,增强肝脏胆固醇的排泄,发挥其对高脂血症的预防和治疗作用.  相似文献   

12.
The purpose of this study was to examine: 1) whether caffeine in the fertilization medium under mineral oil is essential for bovine in vitro fertilization by fully capacitated spermatozoa, 2) the minimum concentration of caffeine that shows an adverse effect on the motility of preincubated spermatozoa. Cumulus-oocyte complexes with heterogeneous-appearing ooplasm were matured in in vitro culture for 24 h and used for insemination. The fertilization rates of the preincubated spermatozoa introduced into the fertilization medium containing 0 mM or 5 mM caffeine were examined. The fertilization rate of the spermatozoa introduced into the medium without caffeine (final concentration of caffeine at fertilization was 0.27-0.35 mM) was significantly higher than that in the medium with 5 mM caffeine (82.4% vs 55.2%, P<0.05). When the final concentration of caffeine at fertilization was reduced ten-fold (0.02-0.03 mM), the fertilization rate was not significantly improved (86.0%). The motility of the preincubated spermatozoa introduced into the fertilization medium containing 0-5 mM caffeine was examined. The sperm motility in the fertilization medium without caffeine was significantly higher than that in the fertilization medium with more than 2 mM caffeine. These results indicate that caffeine in the fertilization medium is not essential for bovine in vitro fertilization by fully capacitated spermatozoa, and that more than 2 mM caffeine has an adverse effect on preincubated (capacitated) sperm motility.  相似文献   

13.
本试验旨在探究绿茶粉及绿茶多酚对犬的抗氧化作用。选用5月龄杂交幼犬15只,随机分为3个组,每组5只。对照组饲喂基础饲粮,绿茶粉组饲喂基础饲粮+1.0%的绿茶粉,绿茶多酚组饲喂基础饲粮+0.25%的绿茶多酚。试验期为84 d。结果表明:与试验开始时相比,试验结束时对照组犬体重增长了162%,绿茶粉组犬体重增长了101%,绿茶多酚组犬体重增长了132%,且绿茶粉组和绿茶多酚组试验结束时犬体重显著低于对照组(P0.05),比对照组分别降低了61%和30%。试验第84天,绿茶粉组及绿茶多酚组犬血清中谷丙转氨酶(ALT)、谷草转氨酶(AST)、乳酸脱氢酶(LDH)活性均显著或极显著低于对照组(P0.05或P0.01),血清超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性极显著高于对照组(P0.01),血清丙二醛(MDA)含量极显著低于对照组(P0.01),肝脏抗氧化基因[谷氨酸半胱氨酸连接酶催化亚基(GCLC)、谷氨酸半胱氨酸连接酶修饰亚基(GCLM)、血红素氧合酶1(HO-1)、过氧化氢酶(CAT)]和Ⅱ相解毒酶基因[谷胱甘肽硫转移酶M1(GSTM1)和醌氧化还原酶1(NQO1)]的mRNA相对表达量显著高于对照组(P0.05)。综上所述,在本试验条件下,在犬饲粮中添加1.0%的绿茶粉或0.25%的绿茶多酚均具有保护肝脏、抗氧化、促进Ⅱ相解毒酶基因表达及控制体重的作用。  相似文献   

14.
Abstract

Cytochrome P450s (CYPs) are the main catalytic enzymes for metabolism by a variety of endogenous and exogenous substrates in mammals, fish, insects, etc. We evaluated the application of a multidrug cocktail on changes in CYP1, CYP2, and CYP3 activity in Turbot Scophthalmus maximus. The probe drugs were a combination of caffeine (5 mg/kg body weight), dapsone (5 mg/kg), and chlorzoxazone (10 mg/kg). After a single intraperitoneal injection of the cocktail, the concentration of all three probe drugs in the plasma increased quickly to a peak and then decreased gradually over 24 h. Pharmacokinetic profiles of the three probe drugs were determined using a noncompartmental analysis, and the typical parameters were calculated. In the assay for CYP induction, pretreatment with rifampicin significantly reduced the typical pharmacokinetic metrics for caffeine and chlorzoxazone, but not dapsone, indicating that the activity of CYP1 and CYP2 in turbot were induced by rifampicin.

Received November 25, 2013; accepted May 29, 2014.  相似文献   

15.
The effects of a hot water infusion and an aqueous acetone extract of green tea (Camellia sinensis) on the motility of infective larvae of the sheep nematodes Teladorsagia circumcincta and Trichostrongylus colubriformis were investigated under in vitro conditions. The infusion and extract dose-dependently inactivated the infective larvae as assessed by the larval migration inhibition (LMI) assay. To determine the components responsible for the inhibitory activity, the hot water infusion and aqueous acetone extract of green tea were fractionated on Sephadex LH-20 and the green tea extract fractions (GTE-I-VIII) characterised by mass spectrometry. The larvae were exposed to increasing concentrations of these GTE fractions. Fractions containing epigallocatechin gallate (EGCG) and proanthocyanidin oligomers were most effective. GTE fractions were more effective against T. circumcincta than T. colubriformis larvae as assessed by the LMI assay.  相似文献   

16.
Ebner, T., Schänzle, G., Weber, W., Sent, U., Elliott, J. In vitro glucuronidation of the angiotensin II receptor antagonist telmisartan in the cat: a comparison with other species. J. vet. Pharmacol. Therap.  36 , 154–160. Glucuronidation of telmisartan comprises nearly its entire metabolic clearance in several mammalian species including human. However, data were lacking for the cat, a species noted for its inability to glucuronidate some drugs. Therefore, the glucuronidation of telmisartan was investigated using feline liver microsomes and compared to liver microsomes of rats, dogs, and human, intestinal human microsomes and cell lines expressing human UDP‐glucuronosyltransferases (UGT). Incubation of telmisartan with cat liver microsomes readily yielded telmisartan glucuronide, and pooled (N = 3 for each gender) cat liver microsomes even showed the highest glucuronidation rate (cat > dog >> human > rat). Michaelis Menten kinetics were observed with Km of 7.5 and 10 μm and Vmax of 3.9 and 3.3 nmol/min/mg for male and female cats, respectively. Confirming the in vitro data, telmisartan glucuronide was detected as the major circulating metabolite in cat plasma. To elucidate which UGT enzymes are involved, telmisartan was incubated with cell lines expressing human UGTs. The highest glucuronidation activity was observed for UGT1A8, UGT1A7, and UGT1A9. In conclusion, telmisartan was effectively glucuronidated in cats. Defects of the UGT1A6 gene in cats do not affect the glucuronidation of telmisartan as it is not a substrate of human UGT1A6.  相似文献   

17.
研究了苜蓿皂苷对SD大鼠胆固醇代谢的影响,并初步探讨其分子机理。取雄性健康SD大鼠32只,随机分为4组,分别为:正常对照组、苜蓿皂苷组、高脂模型组和高脂皂苷组,每组8只。前4周为高脂模型建立期,后4周为灌胃期,正常对照组和苜蓿皂苷组饲喂基础饲粮,其余2组饲喂高脂饲粮,苜蓿皂苷组和高脂皂苷组从第5周开始灌胃240 mg/kg苜蓿皂苷,灌胃4周。测定试验大鼠体重、肝脏系数、血脂水平、粪便和肝脏中的胆固醇、胆汁酸含量,并用实时荧光定量PCR技术检测大鼠肝脏胆固醇7α-羟化酶(CYP7a1)和三磷酸腺苷结合盒转运体G5/三磷酸腺苷结合盒转运体G8(ABCG5/ABCG8) mRNA的表达量。结果表明,1)苜蓿皂苷显著降低高脂大鼠体重、肝脏系数;降低血清中总胆固醇含量,加速胆固醇向肝脏的聚集;增加粪便中胆固醇和胆汁酸的排出; 2)显著增加正常血脂水平大鼠粪便中胆固醇的含量,但对其体重、肝脏系数等影响不大;3)添加苜蓿皂苷后正常和高脂水平SD大鼠肝脏CYP7a1和ABCG5/ABCG8 mRNA的表达量均成倍增加。提示苜蓿皂苷能够调节SD大鼠体内胆固醇的分布,具有良好的降血脂效应,其效应可能与增加CYP7a1和ABCG5/ABCG8 mRNA表达量,加速体内胆固醇、胆汁酸排泄有关。  相似文献   

18.
通过烟焦油对小鼠肝微粒体ANDM和GST的作用,探讨甘草、黄芪、五味子及绿茶的抗烟毒作用。采用钙沉淀法制备肝微粒体,Lowry法测定蛋白含量并测定小鼠肝微粒体中的ANDM、GST活性水平。结果表明,2%LD50(0.01 g/kg)的烟焦油可使小鼠肝脏中ANDM显著升高,对GST的影响不明显,经统计学检验差异无显著性(P>0.05)。大剂量甘草、黄芪、五味子及绿茶组可使焦油升高的ANDM明显降低,并明显升高GST活性,经统计学检验差异有显著性(P<0.01)。说明甘草、黄芪、五味子及绿茶有明显的抗烟毒作用。  相似文献   

19.
In this study, the potential for development of an animal model (GPG46) capable of rapidly detecting chemical carcinogenicity and the underlying mechanisms of action were examined in gpt delta rats using a reporter gene assay to detect mutations and a medium-term rat liver bioassay to detect tumor promotion. The tentative protocol for the GPG46 model was developed based on the results of dose-response exposure to diethylnitrosamine (DEN) and treatment with phenobarbital over time following DEN administration. Briefly, gpt delta rats were exposed to various chemicals for 4 weeks, followed by a partial hepatectomy (PH) to collect samples for an in vivo mutation assay. The mutant frequencies (MFs) of the reporter genes were examined as an indication of tumor initiation. A single intraperitoneal (ip) injection of 10 mg/kg DEN was administered to rats 18 h after the PH to initiate hepatocytes. Tumor-promoting activity was evaluated based on the development of glutathione S-transferase placental form (GST-P)-positive foci at week 10. The genotoxic carcinogens 2-acetylaminofluorene (2-AAF), 2-amino-3-methylimidazo [4,5-f] quinolone (IQ) and safrole (SF), the non-genotoxic carcinogens piperonyl butoxide (PBO) and phenytoin (PHE), the non-carcinogen acetaminophen (APAP) and the genotoxic non-hepatocarcinogen aristolochic acid (AA) were tested to validate the GPG46 model. The validation results indicate that the GPG46 model could be a powerful tool in understanding chemical carcinogenesis and provide valuable information regarding human risk hazards.  相似文献   

20.
The aim of this study was to evaluate the effect of bovine somatotropin (bST) on fetal and placental development during the first third of gestation in beef heifers. Angus heifers (n = 97) were randomly assigned to either receive a 500-mg injection of bST (BST) biweekly on days 0, 15, 29, 43, and 57 of gestation or not receive bST (CTL) throughout the experiment. Body weight (BW) was assessed on days −9, −3, 0, 15, 22, 29, 43, 50, 57, 64, and 77, while blood samples were collected on days 0, 22, 50, and 64. Pregnancy status was determined via transrectal ultrasonography on days 29 and 64. A subset of pregnant heifers (BST, n = 7; CTL, n = 5) were harvested on day 84, and complete gravid reproductive tracts and liver tissue were collected for analysis. Cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A), and uridine 5′-diphospho-glucuronosyltransferase (UGT) activities were determined. Mean change in BW and average daily gain of heifers between fixed-time artificial insemination (day 0) and day 77 did not differ between treatments (P ≥ 0.05). Mean concentrations of insulin-like growth factor 1 (IGF-1) were greater (P < 0.001) in BST (347 ± 27.7 ng/mL) compared with CTL (135 ± 32.8 ng/mL) heifers. Mean placental weight, fetal membrane weight, uterine weight, and ovarian and corpus luteum (CL) weights, as well as fetal morphometric data, did not differ (P ≥ 0.05) between treatments. However, BST heifers had greater (P = 0.03) quantities of combined fetal fluid compared with CTL (521.6 ± 22.9 vs. 429.6 ± 27.14 g, respectively). Tendencies were observed for BST heifers to have reproductive tracts with fewer placentomes (P = 0.08) and fetuses with greater umbilical diameters (P = 0.09) compared with CTL. The activity of CYP1A did not differ (P ≥ 0.05) within the maternal and fetal liver, caruncle, cotyledon, or CL tissue samples between treatments. Furthermore, CYP3A activity was only observed in maternal liver samples and was not different between treatments (P ≥ 0.05). Interestingly, CYP2C activity was greater (P = 0.01) in the liver of BST vs. CTL heifers, and UGT activity was greater (P = 0.02) in the CL from BST heifers compared with CTL. In conclusion, the administration of bST during the first third of gestation increased plasma concentrations of IGF-1, which resulted in an increase in fetal fluid, decrease in placentome number, and greater umbilical diameter, but failed to alter fetal development.  相似文献   

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