Furan in heat‐treated foods: Formation,exposure, toxicity,and aspects of risk assessment

Furan is formed in a variety of heat‐treated foods through thermal degradation of natural food constituents. Relatively high levels of furan contamination are found in ground roasted coffee, instant coffee, and processed baby foods. European exposure estimates suggest that mean dietary exposure to furan may be as high as 1.23 and 1.01 μg/kg bw/day for adults and 3‐ to 12‐month‐old infants, respectively. Furan is a potent hepatotoxin and hepatocarcinogen in rodents, causing hepatocellular adenomas and carcinomas in rats and mice, and high incidences of cholangiocarcinomas in rats at doses ≥2 mg/kg bw. There is therefore a relatively low margin of exposure between estimated human exposure and doses that cause a high tumor incidence in rodents. Since a genotoxic mode of action cannot be excluded for furan‐induced tumor formation, the present exposures may indicate a risk to human health and need for mitigation. This review summarizes the current knowledge on mechanisms of furan formation in food, human dietary exposure to furan, and furan toxicity, and highlights the need to establish the risk resulting from the genotoxic and carcinogenic properties of furan at doses lower than 2 mg/kg bw.     

Ochratoxin A induces oxidative DNA damage in liver and kidney after oral dosing to rats

The nephrotoxic/carcinogenic mycotoxin ochratoxin A (OTA) occurs as a contaminant in food and feed and may be linked to human endemic Balkan nephropathy. The mechanism of OTA-derived carcinogenicity is still under debate, since reactive metabolites of OTA and DNA adducts have not been unambiguously identified. Oxidative DNA damage, however, has been observed in vitro after incubation of mammalian cells with OTA. In this study, we investigated whether OTA induces oxidative DNA damage in vivo as well. Male F344 rats were dosed with 0, 0.03, 0.1, 0.3 mg/kg bw per day OTA for 4 wk (gavage, 7 days/wk, five animals per dose group). Subsequently, oxidative DNA damage was determined in liver and kidney by the comet assay (single cell gel electrophoresis) with/without use of the repair enzyme formamido-pyrimidine-DNA-glycosylase (FPG). The administration of OTA had no effect on basic DNA damage (determined without FPG); however, OTA-mediated oxidative damage was detected with FPG treatment in kidney and liver DNA of all dose groups. Since the doses were in a range that had caused kidney tumors in a 2-year carcinogenicity study with rats, the oxidative DNA damage induced by OTA may help to explain its mechanism of carcinogenicity. For the selective induction of tumors in the kidney, increased oxidative stress in connection with severe cytotoxicity and increased cell proliferation might represent driving factors.     

Hepatoprotective effect of the root extract of Decalepis hamiltonii against carbon tetrachloride-induced oxidative stress in rats

Decalepis hamiltonii, a climbing shrub, grows in the forests of peninsular India and is consumed for its health promoting properties. The hepatoprotective activity of the aqueous extract of the roots of D. hamiltonii with known antioxidant constituents was studied against carbon tetrachloride (CCl₄)-induced oxidative stress and liver injury in rats. Pretreatment of rats with aqueous extract of the roots of D. hamiltonii, single (50, 100 and 200 mg/kg b.w.) and multiple doses (50 and 100 mg/kg b.w. for 7 days) significantly prevented the CCl₄ (1 ml/kg b.w.) induced hepatic damage as indicated by the serum marker enzymes (AST, ALT, ALP, and LDH). Parallel to these changes, the root extract also prevented CCl₄-induced oxidative stress in the rat liver by inhibiting lipid peroxidation and protein carbonylation, and restoring the levels of antioxidant enzymes (SOD, CAT, GPx, GR, and GST) and glutathione. The biochemical changes were consistent with histopathological observations suggesting marked hepatoprotective effect of the root extract in a dose dependent manner. Protective effect of the aqueous extract of the roots of D. hamiltonii against CCl₄-induced acute hepatotoxicity could be attributed to the antioxidant constituents.     

The involvement of oxidative stress in ochratoxin A and fumonisin B1 toxicity in rats

The aim of this study was to find out whether very low doses of nephrotoxic and hepatotoxic mycotoxins ochratoxin A (OTA) and fumonisin B1 (FB1) induce oxidative stress in rat kidney and liver and whether their effect is synergistic. Rats were treated orally with OTA (5 ng/kg b.w. and 50 microg/kg b.w.) and FB1 (200 ng/kg b.w. and 50 microg/kg b.w.), or their combinations. Malondialdehyde (MDA) and protein carbonyls (PCs) concentration in kidney was affected with lower dose of OTA than in liver (p<0.05). FB1 did not affect MDA and PCs concentrations in the liver, while in the kidney both FB1 doses increased MDA concentration (p<0.05). The combination of the lower doses of OTA+FB1 increased the MDA and PCs concentration both in the liver and the kidney, compared to controls and animals treated with respective doses of mycotoxins (p<0.05). The combinations of mycotoxins reduced the catalase activity only in the kidney when compared to controls (p<0.05). In contrast to the increased kidney concentrations of MDA and PCs even with very low doses of OTA and FB1, the activity of catalase and SOD does not change. Combinations of OTA+FB1 affected almost all parameters, which indicates their potential to produce oxidative damage.     

Reverse Effect of Opuntia ficus‐indica L. Juice and Seeds Aqueous Extract on Gastric Emptying and Small‐Bowel Motility in Rat

This study was conducted to compare the effects of juice and seeds on gastric emptying, small‐bowel motility and intestinal ion transport. Separate groups of rats were randomized to receive NaCl, increasing doses of juice (5, 10, and 20 mL/kg, b.w.) or seeds aqueous extract (100, 200, and 400 mg/kg, b.w.). Simultaneously, two other groups were received, the reference drugs; clonidine (1 mg/kg) and yohimbine (2 mg/kg). The charcoal meal was used as a suspension for gastrointestinal motility test. The purgative action of juice was confirmed using the loperamide (5 mg/kg, p.o.) induced constipation. To evaluate the antisecretory effect, we were used as a hypersecretion agent, the castor oil at the dose of 5 mL/kg. Compared to the control and standard groups, we were showed that the prickly pear has an opposite effect on small‐bowel motility and gastric emptying. Indeed, the juice at various doses has a laxative effect of gastrointestinal transit in healthy and constipated‐rats. However, the aqueous extract of the seeds leads to a reduction of motility in normal rats which gives it a remarkable antidiarrhoeal activity, a notable intestinal fluid accumulation decline and electrolyte concentrations reestablishment. Moreover, orally juice administered at different doses accelerated the stomach emptying time in contrast to the seeds aqueous extract. More importantly, a significant variation in the phytochemical constituents levels between juice and seeds was found. These findings confirm the reverse therapeutic effects of this fruit in the treatment of digestive disturbances such as difficulty stool evacuation and massive intestinal secretion, likewise, the gastric emptying process perturbation.     

白芍总苷对高尿酸血症并发肝脏损伤的保护作用

目的：探讨白芍总苷（total glucosides of paeony,TGP）对大鼠高尿酸血症并发肝脏损伤的保护作用。方法：将50只雄性Sprague-Dawley大鼠随机分为5组：正常组、模型组、TGP低剂量组（100 mg/kg）、TGP高剂量组（300 mg/kg）和别嘌醇组（27.0 mg/kg）,每组10只。模型组、TGP低、高剂量组和别嘌醇组大鼠分别按照1.5 mL/100 g的体积灌胃腺嘌呤6.66 mg/mL+氧嗪酸钾100 mg/mL的混合液制造高尿酸血症大鼠模型,每日7:00和20:00各1次,持续3周。每日12:00按剂量分别灌胃给药TGP和别嘌醇,持续5周。5周后,处死大鼠,检测各组大鼠的肝脏脏器指数,血清中总胆固醇（total cholesterol,TC）、甘油三酯（triglyceride,TG）、丙二醛（malondialdehyde,MDA）、超氧化物歧化酶（superoxide dismutase,SOD）、谷草转氨酶（aspartate aminotransferase,AST）、谷丙转氨酶（alanine aminotransferase,A...     

Dose effect on the uptake and accumulation of hydroxytyrosol and its metabolites in target tissues in rats

Hydroxytyrosol (HT) is the most prominent phenolic compound of virgin olive oil and due to its scientifically validated biological activities it is entering to the market as a potentially useful supplement for cardiovascular disease prevention. The aim of the present study was to investigate the relationship between the HT dose intake and its tissue uptake in rats, and thus, providing complementary information in relation to the target‐dose relationship. Rats were given a refined olive oil enriched with HT at different doses (1, 10, and 100 mg/kg) and they were sacrificed after 5 h to ensure the cell tissue uptake of HT and its metabolites. Plasma samples and different organs as liver, kidney, heart and brain were obtained, and HT metabolites were analyzed by UPLC‐MS/MS. The results showed that HT and its metabolites could be accumulated in a dose‐dependent manner basically in the liver, kidney, and brain and were detected in these tissues even at nutritionally relevant human doses. The detection of free HT in liver and kidney was noteworthy. To date, this appears to be the only biologically active form, and thus, it provides relevant information for optimizing the potential applications of HT to prevent certain hepatic and renal diseases. In recent years, HT and its derivatives have led to a great interest from the virgin olive oil producers and manufacturers of nutraceutical supplements. The increasing interest in HT is mainly due to the European Food Safety Agency (EFSA) Panel on Dietetic Products, Nutrition, and Allergies (NDA) scientific opinion that established a cause‐and‐effect relationship between the consumption of olive oil polyphenols and protection of LDL particles from oxidative damage 1 . Based on this positive opinion, the health claim “Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress” was included in the list of health claims 2 , being the only authorized health claim in the European Union regarding polyphenols and health.     

The effects of T-2 toxin exposure on liver drug metabolizing enzymes in rabbit

High doses of T-2 toxin are known to decrease protein synthesis and mono-oxygenase activities in rat liver. The purpose of this study was to investigate whether exposure at a low dose could alter the normal metabolism of the xenobiotic by the liver. Three doses of T-2 toxin, dissolved in olive oil, were orally and daily administered to New Zealand white rabbits for five days. At 0.5mg/kg, three of the five animals died, whereas only a weak decrease in body weight gain and moderate signs of toxicity occurred in rabbits receiving 0.25mg/kg/day, and the body weight increased without signs of toxicity at 0.1mg/kg/day. At 0.25mg/kg/day, total liver microsomal P450 content, and the activities of aminopyrine and benzphetamine N-demethylases, pentoxyresorufin O-depentylase, glutathione S-transferases accepting 1-chloro-2,4-dinitrobenzene and 1,2-dichloro-4-nitrobenzene as substrates, were decreased. By contrast, ethylmorphine and erythromycin N-demethylases, ethoxyresorufin and methoxyresorufin O-dealkylases, aniline hydroxylase, and UDP-glucuronyltransferase accepting p-nitrophenol as substrate, were unaffected. The expression of P450 1A1, 1A2, 2A1, and 2B4, but not P450 2C3 and 3A6, were also decreased, whereas microsomal conjugated dienes, fluorescent substances, and malondialdehyde contents were increased. At 0.1mg/kg/day, neither significant effects on drug metabolizing enzymes nor microsomal oxidative damages were obtained. Taken together, these results suggest that a short exposure time to the mycotoxin would not be associated with significant changes in the normal metabolism of xenobiotics by the liver.     

The induction and persistence of altered sphingolipid biosynthesis in rats treated with fumonisin B1

The fumonisins produced by Fusarium spp. are carcinogenic in rodents and possibly carcinogenic to humans. One action of fumonisins is to inhibit the enzyme ceramide synthase and as a consequence disrupt de novo sphingolipid biosynthesis. Measurement of the ratio of sphinganine (Sa) to sphingosine (So) in urine, serum and tissues has thus been made in various animal species as a marker of exposure to this mycotoxin. In this study in male BDIV rats, the effect of increasing daily gavage doses (0.01?5mg/kg b.w.) of fumonisin B₁ (FB₁) on the Sa/So ratio in various tissues and urine was examined as was the persistence of the effects after cessation of treatment. The lowest dose of FB₁ which induced an alteration of Sa/So in any tissue was 1mg/ kg b.w. The tissue most affected was the kidney, with the liver affected to a much lesser extent and the lung and oesophagus not at all. Only a modest indication of an alteration in Sa/So ratio was obtained in the urine. The large interindividual variations in urinary Sa and So in this strain of rat, even in the absence of FB₁ treatment, made interpretation of these data difficult. After cessation of treatment, the Sa/So ratio returned to normal in kidney after a period of 1?3 weeks. These data suggest that altered Sa/So ratios reflect recent exposure to FB₁ in the rat.     

Protective effect of white tea extract against acute oxidative injury caused by adriamycin in different tissues

Adriamycin (ADR) is an anticancer agent that increases oxidative stress in cells. We evaluated the protective effect of the long term consumption of white tea at two different doses against this drug. For this purpose rats were given distilled water (controls), 0.15 mg (Dose 1) or 0.45 mg (Dose 2) of solid tea extract/kg body weight for 12 months. All the animals received an injection of ADR, except half of the control group, which were given an injection of saline solution. This gave four experimental groups: Control (C), C + ADR, Dose 1 + ADR, and Dose 2 + ADR. The antioxidant activity (in liver, heart and brain microsomes) was analysed. White tea consumption for 12 months, at a non-pharmacological dose, reversed the oxidative damage caused by ADR, on both protein and lipid levels in all three organs. The heart recovered its antioxidant activity only at the highest dose of tea.     

槲皮素通过Nrf2通路对糖尿病大鼠胰腺氧化损伤的拮抗作用机制

目的：探讨槲皮素是否通过核因子E2相关因子2（nuclear factor erythroid 2-related factor 2, Nrf2）通路拮抗糖尿病大鼠胰腺氧化损伤。方法：选取SPF级SD大鼠48 只,随机选取10 只大鼠作为正常对照组,其余38 只大鼠饲喂高脂饲料联合注射30 mg/kg mb链脲佐菌素建立2型糖尿病（type 2 diabetes mellitus,T2DM）模型。以大鼠随机血糖浓度不低于16.7 mmol/L作为造模成功判断标准,按血糖浓度分层将大鼠随机分为T2DM模型组、低剂量槲皮素（L-QU）、高剂量槲皮素（H-QU）干预组,每组10 只,连续灌胃12 周。测定大鼠胰腺组织匀浆液的氧化损伤和抗氧化指标,运用Western Blot、实时定量聚合酶链式反应测定Nrf2、血红素氧合酶1（heme oxygenase 1,HO-1）、谷胱甘肽硫转移酶（glutathione S-transferase,GST）、NADP(H):醌氧化还原酶1（NADP(H):quinone oxido-reductase 1,NQO1）蛋白及其mRNA表达量。结果：与T2DM模型组相比,低、高剂量槲皮素干预显著降低了大鼠血糖浓度和胰腺丙二醛含量（P＜0.05）,减轻胰岛素抵抗,显著提高超氧化物歧化酶等抗氧化酶活力（P＜0.05）,Nrf2以及下游抗氧化酶HO-1、NQO1的蛋白含量和mRNA表达量均显著上升（P＜0.05）。结论：槲皮素可能是通过激活胰腺组织Nrf2信号通路,上调下游抗氧化酶表达,进而减轻T2DM大鼠胰腺氧化损伤,改善胰岛素抵抗,调节血糖水平,从而发挥防治糖尿病的作用。     

Energy Drink Induced Lipid Peroxidation and Oxidative Damage in Rat Liver and Brain When Used Alone or Combined with Alcohol

Energy drinks (ED) are containing large doses of metabolic stimulants and its use with ethanol has increased dramatically among young adults. In this study, we examined the effects of ED exposure either alone or in combination with ethanol on oxidative stress parameters including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH‐Px), and lipid peroxidation parameter malondialdehyde (MDA) in rat. Some histopathological findings were also evaluated. ED exposure led to a dose‐dependent increase in liver MDA compared to the control indicating oxidative damage. Histopathological findings also revealed that ED alone may generate liver damage. Ethanol exposure increased MDA level and SOD, CAT, and GSH‐Px activity in both the brain and the liver. The combination of ethanol and ED produced greater damage which is considered by further increases in SOD and GSH‐Px activity in the brain. Similar results for MDA were observed in both the liver and brain as well. Our findings suggest that ED consumption alone or combination with ethanol may represent a significant public health concern.     

A safety study of oral xanthohumol administration and its influence on fertility in Sprague Dawley rats

Xanthohumol (XN) is a prenylated chalcone, which has been shown to possess a broad range of potential cancer preventive and additional biological activities. In the present study, we have determined the subchronic 4-wk toxicity of XN and monitored its influence on fertility and development of offspring in two fertility studies. Four-week-old female Sprague Dawley (SD) rats were treated with 0.5% XN in the diet or with 1,000 mg XN/kg body weight (b.w.) per day by gavage for 28 days. No remarkable treatment-related changes in general appearance and b.w. occurred during the study. After autopsy, liver, kidney, lung, heart, stomach, and spleen were examined macroscopically and histopathologically. Relative liver weights of animals in both treatment groups were significantly reduced by 30--40% in comparison with the control group, indicating weak hepatotoxicity. Also, mammary glands of treated rats appeared less developed compared to the controls. Consequently, we investigated the influence of XN on rat reproduction. In two fertility studies, XN (100 mg/kg b.w. per day), given either for 4 wk prior to or during mating, gestation, and nursing, did not cause any adverse effects on female reproduction and the development of offspring. Noteworthy, treatment of male rats prior to mating significantly (p=0.027) increased the sex ratio of male to female offspring. Overall, lifelong treatment at a daily dose of 100 mg/kg b.w. in a two-generation study did not affect the development of SD rats.     

Subacute oral toxicity study of benzyl isothiocyanate in rats.

The subacute toxicity of benzyl isothiocyanate (BITC) was investigated in male rats given oral doses of 0, 50, 100 and 200 mg/kg body weight/day for 4 weeks. Body weight gain and food consumption were decreased with increasing doses of BITC. Haematological changes of toxicological relevance were observed in the highest dose group. BITC administration resulted in increased serum cholesterol level in all treatment groups and decreased serum triglycerides level at 200 mg/kg. Renal dysfunction was indicated by reduced urine volume, proteinuria and enhanced urinary lactate dehydrogenase activity. BITC exposure also affected the weights of various organs and caused histological changes in the ductus choledochus, liver, ileum and mesenteric lymph nodes.     

Subacute oral toxicity study of benzyl isothiocyanate in rats

The subacute toxicity of benzyl isothiocyanate (BITC) was investigated in male rats given oral doses of 0, 50, 100 and 200 mg/kg body weight/day for 4 weeks. Body weight gain and food consumption were decreased with increasing doses of BITC. Haematological changes of toxicological relevance were observed in the highest dose group. BITC administration resulted in increased serum cholesterol level in all treatment groups and decreased serum triglycerides level at 200 mg/kg. Renal dysfunction was indicated by reduced urine volume, proteinuria and enhanced urinary lactate dehydrogenase activity. BITC exposure also affected the weights of various organs and caused histological changes in the ductus choledochus, liver, ileum and mesenteric lymph nodes.     

Effect of soybean oligosaccharides on blood lipid,glucose levels and antioxidant enzymes activity in high fat rats

The effect of soybean oligosaccharides on blood lipid levels and oxidative stress in rats fed on high-fat diet was investigated. Rats were divided into five groups of 10 animals each. The high-fat group received a high-fat diet containing 18% (w/w) lipid in the diet (36% of total energy). Animals allocated to the soybean oligosaccharides-treatment groups (I, II and III) received the high-fat diet and orally fed with soybean oligosaccharides at a single dose of 150, 300 and 450 mg/kg body weight, respectively. Control rats received basic diet. Results showed that soybean oligosaccharides significantly reduced abnormal blood glucose, lipid level and oxidative stress in animal models at all doses examined. Soybean oligosaccharides were able to reduce oxidative stress and improve abnormal blood lipid levels induced by high-fat diets. In summary, the present study may be important for reverse cardio-cerebrovascular disease.     

The subacute toxicity of glucosylthiazolidine-4-carbonic acid in rats

Glucosylthiazolidine-4-carbonic acid, an intermediate of the Maillard reaction between D-glucose and L-cysteine, was given in doses of 0, 25, 50 or 100 mg/kg b.w. by oral intubation to male and female rats for 21 days. General appearance, growth, food consumption, haematology, urine analysis and serum chemistry including determinations of enzyme activities, organ weights and macroscopic and microscopic pathology were used as criteria for adverse effects. Effects on the kidneys were indicated by oliguria and decreased specific gravity of the urine in males and histopathological changes of the proximal tubules in females. The no-effect dose established from this study is 25 mg/kg b.w.     

亚硒酸钠对大鼠的亚慢性毒性研究

目的：对常见的硒强化剂亚硒酸钠的亚慢性毒性进行研究。方法：以Wistar大鼠为实验动物,采用固定剂量染毒法以0.470、0.235、0.118mg/kg(1/25～1/100 LD50)剂量连续灌胃12周,停药后恢复观察2周,分别在实验的12、14周末取血及主要脏器,系统研究硒对大鼠生长性能、组织病理变化、血常规、血液生化指标的影响。结果：0.235mg/kg剂量对大鼠生长有一定抑制作用,对主要器官脏器系数、血常规指标、血液生化指标均有不同程度影响,剖检及组织学变化以心、肝、脾、肺、肾、肠道等器官损伤为主。结论：亚硒酸钠对大鼠有亚慢性毒性作用,经口灌胃的最低观察到损害作用剂量(LOAEL)为0.235mg/kg,最大无作用剂量(NOAEL)为0.118mg/kg,对大鼠造成的损伤在短期内部分可逆,无迟发性毒作用。     

Neuroprotective effect of Decalepis hamiltonii roots against ethanol-induced oxidative stress

The neuroprotective potential of the aqueous extract of the roots of Decalepis hamiltonii (D. hamiltonii root aqueous extract-DHRAE) was studied against ethanol-induced oxidative stress in the rat brain. Ethanol, single dose (5 g/kg body weight), induced oxidative stress in the rat brain which was evident from the increased lipid peroxidation and protein carbonylation, reduced glutathione, and suppressed activities of antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase. Pretreatment of rats with multiple doses of DHRAE, 50 and 100 mg/kg b.w., for 7 consecutive days significantly prevented the ethanol-induced oxidative stress. DHRAE, as such, boosted the antioxidant status of the rat brain. The neuroprotective potential of DHRAE can be attributed to the known antioxidant constituents or its interaction with antioxidant response elements (AREs) which needs to be ascertained.