UDP-glucuronyltransferase Activity Research Articles

Low-polar extract from seed of Cleistocalyx nervosum var. paniala modulates initiation and promotion stages of chemically-induced carcinogenesis in rats

BackgroundCleistocalyx nervosum var. paniala is a local fruit mainly cultivated in the north of Thailand. Our previous study has reported that the methanol extract of C. nervosum seed presented antimutagenicity in a Salmonella mutation assay. The present study focused on the effect of a low-polar extract of C. nervosum seed on the early stages of diethylnitrosamine (DEN)- and dimethylhydrazine (DMH)-induced carcinogenesis in rats. MethodsDried C. nervosum seed powder was extracted using dichloromethane. To study its effect on the initiation stage of carcinogenesis of rats, they were fed with various doses of C. nervosum seed extract (CSE) for 21 days. DEN injection was used to initiate hepatocarcinogenesis and partial hepatectomy was performed to amplify mutated hepatocytes resulting in micronucleated hepatocyte formation. To study the role of CSE on the promotion stage, rats were injected with DEN and DMH to induce preneoplastic lesions and the numbers of glutathione S-transferase placental form (GST-P) positive foci in the liver and aberrant crypt foci (ACF) in the colon were measured. This was followed by CSE administration for 10 weeks. The inhibitory mechanisms of CSE on initiation and promotion stages, including xenobiotic metabolism, cell proliferation and apoptosis, were investigated. ResultsThe total phenolic content in CSE was 80.34 ± 2.29 mg gallic acid equivalents (GAE) per g of extract and 2,4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone was found to be a major flavonoid. The main terpenoids in CSE were β-selinene, α-selinene, γ-selinene and o-cymene while 24(Z)-methyl-25-homocholesterol was a major phytosterol. CSE significantly decreased the number of micronucleated hepatocytes in DEN-initiated rats and enhanced the activities of hepatic glutathione S-transferase and UDP-glucuronyltransferase. Furthermore, the formation of preneoplastic lesions in the liver and colon was statistically reduced by CSE. CSE also diminished cell proliferation in the liver and colon indicated by the number of PCNA positive cells. However, CSE did not alter the numbers of apoptotic hepatocytes and colonocytes in DEN- and DMH-initiated rats. ConclusionsThe dichloromethane extract of C. nervosum seed demonstrated chemopreventive effects on chemically-induced carcinogenesis in both initiation and promotion stages in rats. The inhibitory mechanism might be involved in the modulation of hepatic detoxifying enzymes and suppression of hepatocyte and colonocyte proliferation.

Changes in hepatic metabolic enzyme activities and biliary excretion of 4-nitrophenol in streptozotocin induced diabetic rats

Activity of hepatic metabolic enzymes of glucuronidation and sulfation of 4-nitrophenol (PNP) and biliary excretion of its glucuronide (PNP-G) and sulfate (PNP-S) conjugates have been investigated in control and streptozotocin (STZ)-induced diabetic rats. 500 μM PNP solution was luminally perfused in a cannulated jejunal loop for 90 minutes. It was found that biliary excretion of PNP-G was significantly decreased in the diabetic rats. This effect of STZ could be completely reversed by administration of rapid-acting insulin. Activity of hepatic UDP-glucuronyltransferase and β-glucuronidase was also depressed by the STZ pretreatment. Administration of insulin antagonized the inhibitory action of STZ on UDP-glucuronyltransferase, but the reduced activity of β-glucuronidase was not reversed. Biliary excretion of PNP-S was also depressed in the diabetic rats. Whereas, different effects of insulin administration were observed. Namely, the lower biliary excretion rate of PNP-S was not changed after administration of insulin. Activity of the sulfotransferase and the arylsulfatase enzymes was not altered either by STZ pretreatment or by insulin administration. Biliary excretion of PNP was also significantly depressed by STZ and this depression was not changed after insulin administration. The results call attention to hepatobiliary circulation of low molecular weight xenobiotics and their glucuronide and sulfate conjugates.

The combined use of chemical and biochemical markers in Rutilus rutilus to assess the effect of dredging in the lower course of the Ebro River

The lower course of the Ebro River is polluted with high concentrations of organochlorine compounds dumped by a chloro-alkali plant during the last century. A remediation plan, including building of a protective wall, removal and disposal of polluted sediments started in 2012. With the aim of assessing the effects of dredging of contaminated sediments and potential alterations of water quality, areas located upstream (RR) and downstream (BE, A) the chemical plant (FL) were monitored prior (October 2012) and during dredging (June 2013) using roach (Rutilus rutilus) as sentinel organisms. Concentrations of organochlorine compounds (OCs) in fish muscle and biliary levels of polycyclic aromatic hydrocarbons (PAHs), galaxolide (HHCB) and alkyphenols (APEs) were determined together with selected enzymatic activities (7-ethoxyresorufin-O-deethylase (EROD), 7-benzyloxy-4-trifluoromethyl-coumarin O-debenzyloxylase (BFCOD) and UDP-glucuronyltransferase (UGT)) in the liver. The obtained results proved the effectiveness of the wall retaining suspended particles and avoiding further contamination of downstream sites as fish sampled at downstream sites showed up to 9-fold higher concentrations of OCs in muscle during wall construction than during dredging. EROD and UGT activities were induced in fish from downstream sites; however, no clear response to the observed pollution gradient was detected.

Selenium alone or in combination with lycopene modifies liver metabolizing enzymes against galactosamine – A time bound study

Background: Hepatitis is one of the major public health problems worldwide. This study was designed to evaluate the potential hepatoprotective effects of lycopene (Lyco) and selenium (Se) against galactosamine (Gala) induced hepatitis in rats.Materials and Methods: Seventy five (75) male albino rats were grouped into five of fifteen rats each. GP 1: Control. Animals in Groups (II-V) were injected i.p with Gala (300 mg/kg b.w daily) for 5 days. GP III: Rats were orally pretreated with Lyco (15 mg/kg b.w). GP IV: rats were pretreated orally sodium selenite (0.1 mg/kg b.w) by gavages. GP V: Rats treated with both Lyco and Se. The treatment was continuous for 30 days.Results: The levels of serum inflammatory markers interleukine-6 (IL-6), tumor necrosis factor TNF- α, nitric oxide (NO) and malondialdhyde (MDA) were markedly elevated in rats injected with Gala compared with control group. Administration of Lyco combined with Se reversed these effects and significantly reduced the levels of these markers (p<0.001) compared with Gala. In addition, combined treatment resulted in a significant improvement in antioxidant activities as superoxide dismutase (SOD) and catalase compared with untreated. Non-significant changes were recorded in the activities of UDP-glucuronyltransferase and sulphotransferase in rats injected with Gala but the activity of glutathione Stransferase was significantly elevated (p<0.001).Conclusion: The combined effect of Lyco + Se showed a significant hepatoprotective action against Gala induced hepatitis in rats through inhibition of release of inflammatory mediators and enhancement of antioxidant capacity.Key words: Galactosamine- Lycopene- selenium- hepatitis- rats.

Evaluation of the synergistic effect of Allium sativum, Eugenia jambolana, Momordica charantia, Ocimum sanctum, and Psidium guajava on hepatic and intestinal drug metabolizing enzymes in rats.

Aims/Background:This study was to investigated the synergistic effect of polyherbal formulations (PHF) of Allium sativum L., Eugenia jambolana Lam., Momordica charantia L., Ocimum sanctum Linn., and Psidium guajava L. in the inhibition/induction of hepatic and intestinal cytochrome P450 (CYPs) and Phase-II conjugated drug metabolizing enzymes (DMEs). Consumption of these herbal remedy has been extensively documented for diabetes treatment in Ayurveda.Methodology:PHF of these five herbs was prepared, and different doses were orally administered to Sprague–Dawley rats of different groups except control group. Expression of mRNA and activity of DMEs were examined by real-time polymerase chain reaction and high performance liquid chromatography in isolated liver and intestine microsomes in PHF pretreated rats.Results:The activities of hepatic and intestinal Phase-II enzyme levels increased along with mRNA levels except CYP3A mRNA level. PHF administration increases the activity of hepatic and intestinal UDP-glucuronyltransferase and glutathione S-transferase in response to dose and time; however, the activity of hepatic sulfotransferase increased at higher doses.Conclusions:CYPs and Phase-II conjugated enzymes levels can be modulated in dose and time dependent manner. Observations suggest that polyherbal formulation might be a possible cause of herb-drug interaction, due to changes in pharmacokinetic of crucial CYPs and Phase-II substrate drug.

찔레꽃 및 찔레꽃 복합물 추출물이 고지방·고콜레스테롤 식이 흰쥐의 지질 함량 개선에 미치는 영향

본 연구에서는 고지방·고콜레스테롤 식이 흰쥐에서 찔레꽃과 찔레꽃 복합물이 혈청 및 간 조직의 지질대사에 미치는 영향을 관찰하였다. 실험군을 4군으로 나누어 정상 식이군(N군), 고지방·고콜레스테롤 식이군(HF군), 고지방·고콜레스테롤 식이에 찔레꽃을 5% 첨가한 군(HR군), 고지방·고콜레스테롤 식이에 찔레꽃 복합물을 첨가한 군(HRC군)으로 나누었다. 찔레꽃 복합물은 찔레꽃, 뱀딸기풀, 곰보배추, 조릿대로 구성되어 있다. 체중증가량과 식이효율은 HF군이 N군에 비해 유의적으로 증가하였고 HR군과 HRC군이 HF군에 비해 감소하였다. 혈청 중성지질은 HF군이 N군에 비해 유의적으로 증가하였고 HRC군은 유의적으로 크게 감소하였다. 혈청 HDL-cholesterol은 HR군과 HRC군이 HF군에 비해 증가하였다. 혈청 총콜레스테롤과 LDL-cholesterol은 HF군이 N군에 비해 유의적으로 증가하였고, 특히 동맥경화지수에서 HRC군은 HF군에 비해 유의적으로 감소하였다. 간 중성지질과 총콜레스테롤은 HF군이 N군에 비해 유의적으로 증가하였고 HR군과 HRC군은 HF군에 비해 유의적으로 감소하였다. 대변 중성지질과 총콜레스테롤은 HR군과 HRC군이 HF군에 비해 유의적으로 증가하였다. UDPglucuronyl transferase 활성은 HR군과 HRC군이 HF군에 비해 증가하였다. Total bile acid는 HR군과 HRC군이 HF군에 비해 증가하였고, 특히 HRC군은 HF군에 비해 유의적으로 증가하였다. 이러한 결과 찔레꽃과 찔레꽃 복합물은 UDP-glucuronyl transferase 활성, total bile acid 및 지질대사 조절에 효과적으로 활용될 수 있다고 사료된다.

Hepatic biotransformation and antioxidant enzyme activities in Mediterranean fish from different habitat depths

Marine fish are threatened by anthropogenic chemical discharges. However, knowledge on adverse effects on deep-sea fish or their detoxification capabilities is limited. Herein, we compared the basal activities of selected hepatic detoxification enzymes in several species (Solea solea, Dicentrarchus labrax, Trachyrhynchus scabrus, Mora moro, Cataetix laticeps and Alepocehalus rostratus) collected from the coast, middle and lower slopes of the Blanes Canyon region (Catalan continental margin, NW Mediterranean Sea). The xenobiotic-detoxifying enzymes analysed were the phase-I carboxylesterases (CbEs), and the phase-II conjugation activities uridine diphosphate glucuronyltransferase (UDPGT) and glutathione S-transferase (GST). Moreover, some antioxidant enzyme activities, i.e., catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR), were also included in this comparative study. Because CbE activity is represented by multiple isoforms, the substrates α-naphthyl acetate (αNA) and ρ-nitrophenyl acetate (ρNPA) were used in the enzyme assays, and in vitro inhibition kinetics with dichlorvos were performed to compare interspecific CbE sensitivity.Activity of xenobiotic detoxification enzymes varied among the species, following a trend with habitat depth and body size. Thus, UDPGT and some antioxidant enzyme activities decreased in fish inhabiting lower slopes of deep-sea, whereas UDPGT and αNA-CbE activities were negatively related to fish size. A trend between CbE activities and the IC50 values for dichlorvos suggested S. solea and M. moro as potentially more sensitive to anticholinesterasic pesticides, and T. scabrus as the most resistant one. A principal component analysis considering all enzyme activities clearly identified the species but this grouping was not related to habitat depth or phylogeny. Although these results can be taken as baseline levels of the main xenobiotic detoxification enzymes in Mediterranean fish, further research is needed to evaluate their response to environmental contaminant exposure.

Spectrum of UGT1A1 Variations in Chinese Patients with Crigler-Najjar Syndrome Type II.

Crigler–Najjar Syndrome type II (CNS-II) is an autosomal recessive hereditary condition of unconjugated hyperbilirubinemia without hemolysis, with bilirubin levels ranging from 102.6 μmol/L to 342 μmol/L. CNS-II is caused by a deficiency of UDP-glucuronyl transferase (UGT), which is encoded by the UDP-glucuronyl transferase 1A1 gene (UGT1A1). In East Asian populations, the compound homozygous UGT1A1 G71R and Y486D variants are frequently observed in cases with bilirubin levels exceeding 200 μmol/L. In this study, we investigated the spectrum of UGT1A1 variations in Chinese CNS-II patients. We sequenced the enhancer, promoter, and coding regions of UGT1A1 in 11 unrelated Chinese CNS-II patients and 80 healthy controls. Nine of these patients carried variations that are here reported for the first time in CNS-II patients, although they have been previously reported for other types of hereditary unconjugated hyperbilirubinemia. These individual variations have less influence on UGT activity than do the compound homozygous variation (combination of homozygous G71R variant and Y486D variant). Therefore, we propose that the spectrum of UGT1A1 variations in CNS-II differs according to the bilirubin levels.

Inhibitory Effects of Palm Tocotrienol-Rich Fraction Supplementation on Bilirubin-Metabolizing Enzymes in Hyperbilirubinemic Adult Rats

BackgroundPhenylhydrazine, a hemolytic agent, is widely used as a model of experimental hyperbilirubinemia. Palm tocotrienol-rich fraction (TRF) was shown to exert beneficial effects in hyperbilirubinemic rat neonates.AimTo investigate the effects of palm TRF supplementation on hepatic bilirubin-metabolizing enzymes and ocidative stress status in rats administered phenylhydrazine.MethodsTwenty-four male Wistar rats were divided into two groups; one group was intraperitoneally injected with palm TRF at the dose of 30 mg/kg/day, while another group was only given vehicle (control) (vitamin E-free palm oil) for 14 days. Twenty-four hours after the last dose, each group was further subdivided into another two groups. One group was administered phenylhydrazine (100 mg/kg, intraperitoneally) and another group was administered normal saline. Twenty-four hours later, blood and liver were collected for biochemical parameter measurements.ResultsPhenylhydrazine increased plasma total bilirubin level and oxidative stress in the erythrocytes as well as in the liver, which were reduced by the pretreatment of palm TRF. Palm TRF also prevented the increases in hepatic heme oxygenase, biliverdin reductase and UDP-glucuronyltransferase activities induced by phenylhydrazine.ConclusionPalm tocotrienol-rich fraction was able to afford protection against phenylhydrazine-induced hyperbilirubinemia, possibly by reducing oxidative stress and inhibiting bilirubin-metabolizing enzymes in the liver.

Metabolic enzyme activities and drug excretion in the small intestine and in the liver in the rat

The aim of these experiments was the investigation of the correlation between the metabolic enzyme activities and the intestinal and hepatic excretion of p-nitrophenol (PNP) and its metabolites (PNP-glucuronide: PNP-G and PNP-sulfate: PNP-S) in the same group of rats (n = 10). A jejunal loop was perfused with isotonic medium containing PNP in a concentration of 500 μM. The samples were obtained from the luminal perfusion medium and from the bile. For enzyme assays tissue samples were obtained from the liver and jejunum at the end of experiments. Significant differences were calculated by the Student's t-test. The activity of UDP-glucuronyltransferase and sulfotransferase was about three times higher in the liver than in the small intestine. The activity of the ß-glucuronidase was about six times higher, the activity of the arylsulfatase was approximately seven times greater in the liver than in the jejunum. No significant difference was found between the luminal appearance and the biliary excretion of PNP-G. Contrary to these findings, the biliary excretion of PNP-S was significantly higher than the luminal appearance of PNP-sulfate. It can be concluded that no direct correlation exists between the activity of metabolic enzymes and the excretion rate of PNP-metabolites in the liver and in the jejunal segment of the small intestine.

울금(Curcuma longa L.)이 고지방·고콜레스테롤 식이 흰쥐에서의 담즙산 및 UDP-glucuronyl transferase 활성에 미치는 영향

The current study examined the effect of turmeric powder on bile acid and UDP-glucuronyl transferase activity in rats fed a high-fat and -cholesterol diet. Sprague-Dawley male rats weighing 120±10 g were randomly assigned to a normal diet group (N group) and a high-fat and -cholesterol diet group (HF group), which was further divided into a high-fat and high-cholesterol with a 2.5% tumeric powder supplement group (TPA group) and 5% turmeric powder-supplemented group (TPB group). Body weight gain and food efficiency ratio were significantly increased in the N group as compared to the HF group, but they were significantly decreased in turmeric-supplemented groups as compared to the HF group. The total serum cholesterol and TG contents of the turmeric-supplemented groups were decreased as compared to those of the HF group. Especially, the TPB group was significantly decreased as compared to the HF group. The serum LDL-cholesterol and AI of the turmeric-supplemented groups were decreased as compared to the HF group. The hepatic triglyceride contents of all groups supplemented with the tumeric powder were significantly decreased as compared to the HF group. The hepatic UDP-glucuronyl transferase activity of the turmeric-supplemented groups was increased as compared to the HF group. In particular, the TPB group was significantly increased as compared to the HF group. The serum total bile acid contents of the turmeric-supplemented groups were increased as compared to the HF group. These results suggest that tumeric has powerful health benefits that are created via UDP-glucuronyl transferase activity, bile acid, and lipid metabolism.

Developmental triclosan exposure decreases maternal, fetal, and early neonatal thyroxine: A dynamic and kinetic evaluation of a putative mode-of-action

This work tests the mode-of-action (MOA) hypothesis that maternal and developmental triclosan (TCS) exposure decreases circulating thyroxine (T4) concentrations via up-regulation of hepatic catabolism and elimination of T4. Time-pregnant Long-Evans rats received TCS po (0–300mg/kg/day) from gestational day (GD) 6 through postnatal day (PND) 21. Serum and liver were collected from dams (GD20, PND22) and offspring (GD20, PND4, PND14, PND21). Serum T4, triiodothyronine (T3), and thyroid-stimulating hormone (TSH) concentrations were measured by radioimmunoassay. Ethoxy-O-deethylase (EROD), pentoxyresorufin-O-depentylase (PROD) and uridine diphosphate glucuronyltransferase (UGT) enzyme activities were measured in liver microsomes. Custom Taqman® qPCR arrays were employed to measure hepatic mRNA expression of select cytochrome P450s, UGTs, sulfotransferases, transporters, and thyroid hormone-responsive genes. TCS was quantified by LC/MS/MS in serum and liver. Serum T4 decreased approximately 30% in GD20 dams and fetuses, PND4 pups and PND22 dams (300mg/kg/day). Hepatic PROD activity increased 2–3 fold in PND4 pups and PND22 dams, and UGT activity was 1.5 fold higher in PND22 dams only (300mg/kg/day). Minor up-regulation of Cyp2b and Cyp3a expression in dams was consistent with hypothesized activation of the constitutive androstane and/or pregnane X receptor. T4 reductions of 30% for dams and GD20 and PND4 offspring with concomitant increases in PROD (PND4 neonates and PND22 dams) and UGT activity (PND22 dams) suggest that up-regulated hepatic catabolism may contribute to TCS-induced hypothyroxinemia during development. Serum and liver TCS concentrations demonstrated greater fetal than postnatal internal exposure, consistent with the lack of T4 changes in PND14 and PND21 offspring. These data support the MOA hypothesis that TCS exposure leads to hypothyroxinemia via increased hepatic catabolism; however, the minor effects on thyroid hormone metabolism may reflect the low efficacy of TCS as thyroid hormone disruptor or highlight the possibility that other MOAs may also contribute to the observed maternal and early neonatal hypothyroxinemia.

The Significance of Enterohepatic Circulation in the Causation Neonatal Hyperbilirubinemia

Sir, This is in reference to the study by Rana et al.[1] A robust triple-blind design, appropriate sample-size, and statistical methods–sensitivity analysis and effect-size estimation– employed by the authors could well make the investigation a landmark study evaluating the role of zinc in the prevention of hyperbilirubinemia in neonates. However, the study simultaneously conjures-up an important question about the role of enterohepatic circulation (EHC) in the causation of neonatal jaundice which may also have implications on the physiological doctrine for the intervention tested. Overproduction of bilirubin from heme is considered the most prevalent mechanism of neonatal hyperbilirubinemia apart from impaired uptake, conjugation, and EHC. We have limited instances where EHC is considered the prime mechanism for jaundice, e.g., pyloric stenosis, lower intestinal atresia, paralytic ileus, and meconium-plug-syndrome (virtually no removal of bilirubin due to distal obstruction). There is limited data to suggest that the resorption of bilirubin from the intestine can be a major cause of neonatal physiologic jaundice [2]. It has been stated that neonatal hyperbilirubinemia is exacerbated–if not caused–by enhanced bilirubin resorption through EHC [3]. In fact, more obvious than EHC, a markedly reduced UDP-glucuronyl transferase activity is noted in pyloric stenosis [3]. Enhanced EHC induced by human milk has a putative role in prolonging ‘breastmilk jaundice’ [4]. In the past, various strategies have been employed to counteract EHC with inconsistent results, in terms of the incidence and severity of jaundice [5]. Consequently, it is advised that such interventions are at the best used as an adjuvant, along with more established modalities like phototherapy [6]. The results of the present study by Rana et al., showing no significant reduction in the incidence of hyperbilirubinemia, requirement of phototherapy and mean STB (serum total bilirubin) at 72 h, are in line with the outcomes of previous studies employing other agents. Therefore, although past studies have suggested that EHC may play a significant role in the bilirubin metabolism, it appears less likely that EHC is a major cause of neonatal hyperbilirubinemia, though it may play some contributory role in prolonging physiological jaundice. Therefore, negative results of these studies probably have a bearing on the underlying doctrine of ‘prevention of hyperbilirubinemia by clogging-up EHC’, irrespective of the agent (agar, charcoal, cholestyramine or zinc) employed. Other limitations of the study were the use of nonstandardized oral zinc dose, lack of serum zinc level monitoring, inadequate reporting of the adequacy of breastfeeding and vomited and/or skipped doses, and delayed initiation of the intervention.

고추씨 에탄올 추출물이 콜레스테롤 흡착능 및 UDP-glucuronyl transferase 활성에 미치는 영향

본 연구에서는 고추씨 에탄올추출물이 콜레스테롤 흡착능 및 UDP-glucuronyl transferase 활성에 미치는 영향을 관찰하였다. In vitro 콜레스테롤 흡착능에서는 대조군에 비해 고추씨 에탄올추출물 모든 농도에서 유의적으로 증가하였다. In vivo에서 실험동물은 체중 <TEX>$100{\pm}10$</TEX> g 내외의 Sprague-Dawley계 수컷 흰쥐를 사용하였으며, 실험군은 정상식이를 공급한 정상군과 고지방 고콜레스테롤 식이 실험군으로 나누고 고지방 고콜레스테롤 실험군을 다시 고추씨 에탄올추출물을 공급하지 않은 군(HF groups), 0.1% 공급한 군(HEA group), 0.2%을 공급한 군(HEB group) 및 0.5%을 공급한 군(HEC group), 5군으로 나누고 각 군당 8마리씩 3주간 사육하였다. 체중증가량은 정상군에 비해 HF 군에서 유의적으로 증가하였고 고추씨 에탄올추출물을 공급한 모든 군에서 HF 군에 감소하였으나 유의적인 차이는 없었다. 식이효율은 고추씨 에탄올추출물을 각각 0.1%, 0.2% 및 0.5% 공급한 군에서는 HF군에 비해 유의적이지는 않았지만 감소하는 경향을 보였다. 간조직의 총콜레스테롤 및 중성지질 함량은 정상군에 비해 HF 군에서 유의적으로 증가하였고 HF 군에 비해 HEA, HEB 및 HEC군에서는 유의적이지는 않았지만 다소 감소하는 경향을 나타내었다. UDP-glucuronyl transferase 활성에서는 정상군에 비해 HF 군에서 증가되었고, 고추씨 에탄올추출물 공급군인 HEC 군에서는 HF 군에 비해 유의적으로 증가되어 가장 높은 활성을 나타내었다. 혈청중의 총콜레스테롤 및 중성지방 농도는 정상군에 비해 HF 군에서 유의적으로 증가하였고, HEA, HEB 및 HEC 군에서 HF 군에 비해 감소하였다. HDL-콜레스테롤은 정상군에 비해 HF 군에서 유의적으로 감소하였으나 HEA, HEB 및 HEC 군에서는 HF 군에 비해 정상군 수준으로 증가하는 경향을 보였다. 반면, LDL-콜레스테롤은 HF 군에서 정상군에 비해 유의적으로 증가하였으나 HEA, HEB 및 HEC 군에서는 모두 유의적 감소를 나타내었다. 대변중의 총콜레스테롤 함량은 정상군에 비해 HF 군에서 유의적으로 증가하였고 HF 군에 비해 특히 고추씨 에탄올추출물 공급군 HEB 군 및 HEC 군에서 증가하는 경향을 나타내었으나 유의적인 차이는 없었다. 중성지질 함량은 정상군에 비해 HF 군에서는 유의적이지는 않았지만 증가되었고, 고추씨 에탄올추출물을 공급한 HEB군 및 HEC 군에서 HF 군에 비해 다소 증가하는 경향을 나타내었다. 따라서 고추씨 에탄올 추출물은 콜레스테롤 흡착능에서 효과적으로 작용하였으며 고지방 고콜레스테롤 식이 흰쥐의 UDP-glucuronyl transferase 활성 및 지질대사에 효과적으로 작용하였음을 규명하였다. The purpose of this study was to investigate the effects of ethanol extracts from red pepper seeds on cholesterol adsorption capacity and UDP-glucuronyl transferase activity. In vitro cholesterol adsorption capacity of 2%, 5% and 10% ethanol extracts from red pepper seed groups were significantly higher than that of the control group. Sprague-Dawley strain male rats weighing <TEX>$100{\pm}10$</TEX> g were randomly assigned to one normal diet N group and experimental groups fed high fat and high cholesterol diet, which were divided into HF (0.0%), HEA (0.1%), HEB (0.2%), and HEC (0.5%) groups according to the amount of ethanol extracts from red pepper seeds added to their basal diet. The body weight gain in the HF group was higher than that in the N group, and those in the HEA, HEB and HEC groups were lower than that in the HF group However, there were no statistically significant differences among the all the groups. The hepatic triglyceride and total cholesterol contents in the N group was significantly lower than that in the HF group, and those in the HEA, HEB and HEC groups were lower than that in the HF group. The hepatic UDP-glucuronyl transferase activity in the N group was lower than that of the HF group and those in the HEA, HEB and HEC groups were lower than that of the HF group. The serum total cholesterol and triglyceride contents of the HF group were significantly higher than that of the N group, and those of the HEA, HEB and HEC groups were lower than that of the HF group. The serum HDL-cholesterol contents in all groups supplemented with the ethanol extracts from red pepper seeds were significantly higher than that of the HF group. The serum LDL-cholesterol contents of the HF group were significantly higher than that of the N group, and those of the HEA, HEB and HEC groups were lower than that of the HF group. The fecal total cholesterol contents were significantly higher in the HF group compared to the N group, and those of the HEB and HEC groups were lower than that of the HF group. The fecal triglyceride contents in the N group was higher than that of the HF group, and those of the HEA, HEB and HEC groups were lower than that of the HF group. This study suggested that the ethanol extracts from red pepper seeds have powerful health benefits by the UDP-glucuronyl transferase activity and lipid metabolism.

Acetaminophen Pharmacokinetics in Children With Nonalcoholic Fatty Liver Disease

: The aim of the study was to evaluate UDP-glucuronyltransferase activity and the pharmacokinetics of a single oral dose of acetaminophen (APAP) in children with nonalcoholic fatty liver disease (NAFLD). : Twelve boys 10 to 17 years old with biopsy-proven NAFLD and 12 age- and sex-matched controls without NAFLD were recruited. Following administration of a single oral dose of APAP (5 mg/kg, maximum 325 mg), APAP and its glucuronide metabolite (APAP-G) were measured in plasma, urine, and sputum at various intervals up to 24 hours. The activity of UDP-glucuronyltransferase was estimated by the plasma ratio of APAP-G to APAP at 4 hours. : Following administration of APAP, children with NAFLD had significantly higher concentrations of APAP-G in serum (P = 0.0071) and urine (P = 0.0210) compared with controls. No significant differences in APAP pharmacokinetics parameters were observed between the 2 groups. : APAP glucuronidation is altered in children with fatty liver disease. Despite the altered disposition of this metabolite, the pharmacokinetics of a single 5 mg/kg dose of APAP is the same in children with NAFLD as in children with normal liver function.

Comparison of the Ability of Myricetin and Quercetin to Modulate the Oxidative DNA Damage Induced by Heterocyclic Amines

The aim of the present study was to compare the ability of the myricetin and quercetin to modulate the oxidative DNA damage induced by 2-amino-3, 8- dimethylimidazo [4,5-f] quinoxaline (8-MeIQx), 2-amino- 3, 4, 8- trimethylimidazo [4, 5-f]-quinoxaline (4,8-diMeIQx) and 2-amino-1-methyl-6-phenyl-imidazo [4,5-b] pyridine (PhIP), in human hepatoma cells. DNA damage (strand breaks and oxidized purines/pyrimidines) was evaluated by the alkaline single-cell gel electrophoresis or comet assay. None of the myricetin and quercetin concentrations tested protected against 8-MeIQx, 4, 8-diMeIQx and PhIP-induced DNA strand breaks. The oxidized pyrimidines induced by 4, 8-diMeIQx and PhIP were reduced by myricetin but not by quercetin. Quercetin reduced the oxidized purines induced by 8-MeIQx and PhIP, while myricetin also reduced the induced by 4, 8-diMeIQx. One feasible mechanism by which myricetin and quercetin exert their protective effect towards HCAs-induced oxidative DNA could be related in part to the reduction of human CYP1A1. Another mechanism claimed to be responsible for the protective effect of myricetin and quercetin is the induction of phase II metabolizing enzymes such as UDP-glucuronyltrasferase (UGT). The ethoxyresorufin O-deethylation (CYP1A1) activity was moderately inhibited by myricetin, while little effect was observed by quercetin. On the contrary, quercetin showed the greatest increase on UDP-glucuronyltransferase activity. However, these are not the only mechanisms by which myricetin and quercetin exert their protective effect, other mechanisms such as stimulation of the repair of carcinogen-induced DNA damage and or the free radical scavenging efficiency have been also implicated. In conclusion, our results clearly indicate that myricetin was more efficient than quercetin to prevent DNA damage (oxidized purines and pyrimidines) induced by the three HCAs evaluated. This protective effect depends on the chemical structure of flavonoid and the mutagen studied.

Precision-Cut Slices as a Tool for Studying Phase II Drug Metabolism in Rat Small Intestine in Vitro

ABSTRACTA wide range of endogenous and exogenous compounds including many drugs and their metabolites are inactivated by phase II drug metabolism enzymes UDP-glucuronyltransferase and glutathione S-transferase. The aim of the study was to set up an intestinal precision-cut slice technique for evaluating phase II drug metabolism in rat small intestine. The enzyme activity of UDP-glucuronyltransferase and glutathione S-transferase was measured up to 4 h of incubation and compared with those from intestinal cells obtained by mucosa scraping technique. The results from our study suggest that the activity of both phase II drug metabolism enzymes remains constant at least for a period of 4 h. Both intestinal preparations exhibit phase II metabolic activities at similar rates, but precision-cut intestinal slices have a longer life span. They remain viable up to 24 h of incubation. Precision cut slices might be reliable and quite simple system for evaluating xenobiotic phase II metabolism in rat intestine in vitro.

Effects of (+)catechin and (−)epicatechin on heterocyclic amines-induced oxidative DNA damage

The aim of the present study was to evaluate the protective effect of (+)-catechin and (-)-epicatechin against 2-amino-3,8- dimethylimidazo[4,5-f]quinoxaline (8-MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]-quinoxaline (4,8-diMeIQx) and 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP)-induced DNA damage in human hepatoma cells (HepG2). DNA damage (strand breaks and oxidized purines/pyrimidines) was evaluated by the alkaline single-cell gel electrophoresis or comet assay. Increasing concentrations of 8-MeIQx, 4,8-diMeIQx and PhIP induced a significant increase in DNA strand breaks and oxidized purines and pyrimidines in a dose-dependent manner. Among those, PhIP (300 µm) exerted the highest genotoxicity. (+)-Catechin exerted protection against oxidized purines induced by 8-MeIQx, 4,8-diMeIQx and PhIP. Oxidized pyrimidines and DNA strand breaks induced by PhIP were also prevented by (+)-catechin. Otherwise, (-)-epicatechin protected against the oxidized pyrimidines induced by PhIP and the oxidized purines induced by 8-MeIQx and 4,8-diMeIQx. One feasible mechanism by which (+)-catechin and (-)-epicatechin exert their protective effect towards heterocyclic amines-induced oxidative DNA damage may be by modulation of phase I and II enzyme activities. The ethoxyresorufin O-deethylation (CYP1A1) activity was moderately inhibited by (+)-catechin, while little effect was observed by (-)-epicatechin. However, (+)-catechin showed the greatest increase in UDP-glucuronyltransferase activity. In conclusion, our results clearly indicate that (+)-catechin was more efficient than (-)-epicatechin in preventing DNA damage (strand breaks and oxidized purines/pyrimidines) induced by PhIP than that induced by 8-MeIQx and 4,8-diMeIQx.

Effect of cigarette smoke on mutagenic activation of environmental carcinogens by cytochrome P450 2A8 and inactivation by glucuronidation in hamster liver

To elucidate the mechanism underlying suppression of N-nitrosobis(2-oxopropyl)amine (BOP)-induced hamster pancreatic carcinogenesis by cigarette smoke (CS), hepatic levels of microsomal cytochrome P450 (CYP) enzymes, mutagenic activation of environmental carcinogens and three types of uridine diphosphate-glucuronyltransferase (UDPGT) and sulphotransferase (ST) activities were assayed in male Syrian golden hamsters and F344 rats exposed to CS. Immunoblot analyses of microsomal CYP proteins revealed induction of constitutive CYP1A2 (2.6-fold increase) and 2A8 (4.0-fold increase) and induction of CYP1A1 and constitutive CYP1A2 (3.9-fold increase) in rats following exposure to CS for 4 weeks using a Hamburg type II smoking machine. CS exposure enhanced mutagenicities of four heterocyclic amines in the presence of liver S9 in both species, whereas the mutagenicities of aflatoxin B(1) (AFB(1)), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were significantly increased by CS in hamsters but not in rats. However, no CS-induced alterations in the mutagenic activities of other carcinogens, including BOP and other pancreatic carcinogens, were observed in either species. Application of several CYP inhibitors revealed that the mutagenic activities of MeAαC, AFB(1) and NNK in the hamster liver S9 were partly associated with CYP2A8, whereas those of the three pancreatic carcinogens were selectively associated with CYP2B. CS enhanced UDPGT activities towards 4-nitrophenol (4-NP) (1.9- to 2.0-fold) but did not affect those of bilirubin, testosterone UDPGTs and three STs in both species. Together with the previous findings that BOP does not induce tumourigenesis in rats and that the glucuronidation of β-oxypropylnitrosamines is higher in rats than in hamsters, suppression of BOP-induced pancreatic carcinogenesis by CS might be attributed to increased detoxification by 4-NP UDPGT and not decreased CYP2B activation. This is the first demonstration of the induction of CYP2A protein by CS; CYP2A protein polymorphisms have been associated with oral and pulmonary carcinogenesis in smokers.

Differential sensitivity of CYP1A to 3,3′,4′,4-tetrachlorobiphenyl and benzo(a)pyrene in two Lepomis species

Although Lepomis species are abundant in a wide variety of habitats throughout North America and could serve as potentially valuable biomonitoring tools, few studies have examined the induction of pollutant biomarkers in this genus. We hypothesized that the induction of cytochrome P-450 1A (CYP1A), a sensitive and widely used indicator of response to aquatic contaminants, would serve as an effective biomarker of organic pollutant exposure in Lepomis species. We examined the response of CYP1A and two of the major pollutant-responsive phase II enzymes, glutathione S-transferase (GST), and uridine diphosphate glucuronyltransferase (UDPGT), in Lepomis exposed to organic pollutants under laboratory and field conditions. Two Lepomis species (longear sunfish, Lepomis megalottis and bluegill, Lepomis macrochirus) were exposed in the laboratory via intraperitoneal injection to corn oil (vehicle), benzo(a)pyrene (BaP) (10 and 50 mg/kg), a polynuclear aromatic hydrocarbon (PAH) or 3,4,3′,4′-tetrachlorobiphenyl (PCB 77) (0.1 and 1.0 mg/kg), a dioxin-like planar halogenated aromatic hydrocarbon (HAH), and sacrificed 2 (BaP) or 7 (corn oil, PCB77) days later. Lepomis hepatic CYP1A exhibited differential sensitivity to these two classes of environmental contaminants. CYP1A activity was weakly induced in bluegill exposed to 1.0 mg/kg PCB 77 (3 fold induction over controls) but strongly induced in both bluegill and longear sunfish exposed to 50 mg/kg BaP (37 and 15 fold induction over controls, respectively). In contrast, hepatic GST activity in both species remained unchanged following the treatment with either compound and hepatic UDPGT activity, which was assessed only in BaP-treated longear sunfish, was unaffected by that chemical, indicating these phase II enzymes may not be sensitive pollutant biomarkers in this genus. Further, longear sunfish collected from a PCB contaminated site displayed relatively low levels of CYP1A activity despite PCB body burdens associated with strong induction of CYP1A activity in other fish species. The strong induction of CYP1A by BaP with much weaker CYP1A response to PCB indicates that CYP1A in Lepomis sp. could be an excellent biomarker for PAH pollution, but may not be a reliable indicator of site contamination by halogenated hydrocarbons. We conclude that Lepomis species provide a useful model for examining the regulation and potential consequences of differential pollutant sensitivity, but that CYP1A in these species should be used with caution as an indicator of halogenated contaminants.