Alterations in brush border membrane enzymes, carbohydrate metabolism and oxidative damage to rat intestine by potassium bromate

Effects of Arbutin on Potassium Bromate-Induced Erythrocyte Toxicity in Rats: Biochemical Evaluation of Some Metabolic Enzyme Activities In Vivo and In Vitro

In the present study, the inhibitory effect of potassium bromate on the pentose phosphate pathway and intracellular antioxidant systems enzymes (glucose 6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), glutathione reductase (GR), glutathione S-transferase (GST), and thioredoxin reductase (TrxR)) and the role of arbutin in ameliorating this inhibition were investigated. In the in vivo phase of the study, Wistar Albino rats (28 male adults) were randomly divided into four groups. Control (n = 7): isotonic serum (0.5 mL, i.p), potassium bromate group (n = 7): potassium bromate (100 mg/kg), arbutin group (n = 7): arbutin (i.p.) (50 mg/kg/day), potassium bromate + arbutin, and Group (n = 7): potassium bromate (100 mg/kg) + arbutin (50 mg/kg/day) (i.p). The results of in vivo study showed that the activities of G6PD, 6PGD, GR, and TrxR enzymes were strongly inhibited in potassium bromate groups (p < 0.05). It was determined that GST enzyme activity decreased in the potassium bromate group, but this decrease was not statistically significant compared to the control group (p ⩾ 0.05). A statistically significant increase was found in G6PD, 6PGD, GST, and TrxR enzyme activities in the arbutin group compared to the control group (p < 0.05). The increase in GR enzyme activity was not statistically significant (p ⩾ 0.05). The potassium bromate + arbutin group's enzyme activity increased in comparison to the potassium bromate group and was discovered to be closer to the control group. It was found that potassium bromate inhibited the 6PGD enzyme obtained from rat erythrocyte tissues with IC50 = 346 μM value and Ki = 434.4 μM ± 6.1 value, and the inhibition was noncompetitive.

Potassium bromate – inhalable fraction. Documentation of proposed values of occupational exposure limits (OELs)

Potassium bromate (V), (KBrO3) exists as white crystals, crystalline powder or granules. It is highly soluble in water, tasteless and odourless. Potassium bromate is a strong oxidizing agent. In the past it has been used as food additive in flour milling, as an ingredient in fish-paste in Japan, in cheese making, in beer malting, as a component of cold hair wave liquid and an oxidizing compound. Moreover, bromate is formed as a by-product of water disinfection by ozonation and is frequently detected in tap and bottled water. In fact bromate is one of the most prevalent disinfection by-product of surface water. Occupational exposure to potassium bromate occurs mainly in production plants during packaging processes. In Poland, about 1 160 persons were exposed to this compound in 2016. Bromate caused many acute poisonings by accidental ingestion, mainly among children, and more often ingested for tentative suicide by young women, especially hairdressers. In the acute phase of poisoning, gastrointestinal disturbances, irreversible hearing loss, and acute renal failure were observed. Acute renal failure was associated with hemolytic uremic syndrome. There are no data on chronic intoxication of humans by potassium bromate and epidemiological studies on this subject. On the basis of the value of median lethal dose (LD50) per os in rat, potassium bromate has been classified as a compound belonging to the category „Toxic”. Major toxic signs and symptoms in animals after a single intragastric administration of potassium bromate were tachypnea, hypothermia, diarrhea, lacrimation, suppression of locomotor movement, ataxic gait, and animals lying in a prone position. At autopsy the major findings were strong hyperemia of glandular stomach mucosa and congestion of lungs. Microscopically, necrosis and degenerative changes of the proximal tubular epithelium and hearing cells of internal ear were found. It was stated that the compound is not irritating, corrosive or sensitizing. In subchronic and chronic exposure of rodents, potassium bromate led to liver and kidney dysfunction and tubular epithelial damage. Potassium bromate had mutagenic and clastogenic effects. It induced point mutations, structural chromosome aberrations, micronuclei in polychromatic erythrocytes in male mice, DNA oxidative damage by modification of deoxyguanosine to 8-hydroxydeoxyguanosine, and DNA double-strand breakage. Potassium bromate induced neoplasms in rodents and exerted promotion effect in comparison with well-known carcinogens. Besides from preneoplastic changes, expressed by high incidences of renal cell tumors and dysplastic foci, bromate induced solid neoplasms, such as adenomas and adenocarcinomas in a rat kidney and thyroid, and mesotheliomas of peritoneum and tunica vaginalis testis. The European Union classified potassium bromate as a substance that can cause cancer (Group 1.B), whereas IARC classified it as a presumably carcinogenic agent for human (Group 2.B). In principle, effects of bromate on reproduction and ontogenetic development of offspring were not observed. Animal studies suggest that a kidney is a critical organ in the exposure to potassium bromate. The results of subchronic exposure of male rats to potassium bromate administered with drinking water were used to calculate the value of MAC-NDS. The critical effects in kidney were: an increase of organ weight and dose-dependent histopathological alterations defined as epithelium urinary tract hypertrophy. The NOAEL value is 1.5 mg/kg b.w./day. For the calculation of the maximum allowable concentration (MAC) value, 5 uncertainty factors with total value of 24 were used. Based on this estimation it is proposed to accept the MAC-TWA value for potassium bromate at 0.44 mg/m3. The risks of kidney and thyroid cancer in condition of occupational exposure are 2.2 · 10-3 and 0.6 · 10-3, respectively. There is no reason to determine the value of short-term exposure limit (STEL) and the biological exposure index (BEI). „Carc.1.B” notation (carcinogenic substance) was proposed

Effect of Potassium Bromate on the Liver of Adult Male Albino Rat and A Possible Protective Role of Vitamin C: Histological, Immunohistochemical, and Biochemical Study

Potassium bromate (KBrO3 ) is a food additive which is used primarily as a maturing agent for flour. It is proved as a toxic agent with significant reduction in the activities of antioxidant capacity. The therapeutic efficacy of vitamin C as antioxidant may provide a possible solution to KBrO3 mediated oxidative damage. Twenty four adult male albino rats were used to evaluate the protective role of vitamin C against KBrO3 induced hepatotoxicity and divided into four groups; Group 1 (control), Group 2: received 30 mg/Kg/day vitamin C orally for 4 weeks, Group 3: received 20 mg/Kg/dose KBrO3 orally twice weekly for 4 weeks and Group 4: received both KBrO3 and vitamin C. Liver specimens were processed for histological study by light and electron microscopes and stained immunohistochemically to detect glial fibriller acidic protein (GFAP). Serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were estimated as well as the levels of malondialdehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD) activities in all dissected tissues were determined. KBrO3 induced histological alterations in the form of degeneration, cellular infiltration and significant increase in collagen deposition in portal tracts with a significant increase in immunoexpression of GFAP. Significant rise in serum levels of AST, ALT, and MDA in liver tissues were recorded. However, levels of GSH and SOD were significantly decreased. Most of these changes were improved by vitamin C treatment. In conclusion, vitamin C ameliorates the histological and biochemical alterations of the liver induced by KBrO3 . Anat Rec, 299:1256-1269, 2016. © 2016 Wiley Periodicals, Inc.

Biological properties of Alsidium corallinum and its potential protective effects against damage caused by potassium bromate in the mouse liver

In the course of searching for hepatoprotective agents from natural sources, the protective effect of chemical constituents of the marine red alga Alsidium corallinum (A. corallinum) against potassium bromate (KBrO3)-induced liver damage in adult mice was investigated. The in vitro antioxidant and antibacterial properties of A. corallinum were firstly investigated. Then, A. corallinum was tested in vivo for its potential protective effects against damage caused by KBrO3 in mice models divided into four groups: controls, KBrO3, KBrO3 + A. corallinum, and A. corallinum. Our results demonstrated the rich composition of A. corallinum in antioxidant compounds like phenolics, flavonoids, anthocyanins, polysaccharides, chlorophyll and carotenoids. Its antioxidant activity was also confirmed using β-carotene bleaching by linoleic acid assay, reducing sugar test and trolox equivalent antioxidant capacity. The ethanolic extract of A. corallinum also showed good inhibition of the tested bacteria. The coadministration of the red alga associated to the KBrO3 alleviated hepatotoxicity as monitored by the improvement of hepatic oxidative stress biomarkers and plasma biochemical parameters, when compared to the KBrO3-treated mice. These results were confirmed by the improvement of histological and molecular changes. Treatment with A. corallinum prevented liver damage induced by KBrO3, thus protecting the body against free radicals and reducing inflammation and hypercholesterolemia risks.

Chemoprotective effect of taurine on potassium bromate-induced DNA damage, DNA-protein cross-linking and oxidative stress in rat intestine

Potassium bromate (KBrO3) is widely used as a food additive and is a major water disinfection by-product. It induces multiple organ toxicity in humans and experimental animals and is a probable human carcinogen. The present study reports the protective effect of dietary antioxidant taurine on KBrO3-induced damage to the rat intestine. Animals were randomly divided into four groups: control, KBrO3 alone, taurine alone and taurine+ KBrO3. Administration of KBrO3 alone led to decrease in the activities of intestinal brush border membrane enzymes while those of antioxidant defence and carbohydrate metabolism were also severely altered. There was increase in DNA damage and DNA-protein cross-linking. Treatment with taurine, prior to administration of KBrO3, resulted in significant attenuation in all these parameters but the administration of taurine alone had no effect. Histological studies supported these biochemical results showing extensive intestinal damage in KBrO3-treated animals and greatly reduced tissue injury in the taurine+ KBrO3 group. These results show that taurine ameliorates bromate induced tissue toxicity and oxidative damage by improving the antioxidant defence, tissue integrity and energy metabolism. Taurine can, therefore, be potentially used as a therapeutic/protective agent against toxicity of KBrO3 and related compounds.

Proteome changes in the small intestinal mucosa of broilers (Gallus gallus) induced by high concentrations of atmospheric ammonia

Background

Ammonia is a well-known toxicant both existing in atmospheric and aquatic system. So far, most studies of ammonia toxicity focused on mammals or aquatic animals. With the development of poultry industry, ammonia as a main source of contaminant in the air is causing more and more problems on broiler production, especially lower growth rate. The molecular mechanisms that underlie the negative effects of ammonia on the growth and intestine of broilers are yet unclear. We investigated the growth, gut morphology, and mucosal proteome of Arbor Acres broilers (Gallus gallus) exposed to high concentrations of atmospheric ammonia by performing a proteomics approach integrated with traditional methods.

Results

Exposure to ammonia interfered with the development of immune organ and gut villi. Meanwhile, it greatly reduced daily weight gain and feed intake, and enhanced feed conversion ratio. A total of 43 intestinal mucosal proteins were found to be differentially abundant. Up-regulated proteins are related to oxidative phosphorylation and apoptosis. Down-regulated proteins are related to cell structure and growth, transcriptional and translational regulation, immune response, oxidative stress and nutrient metabolism. These results indicated that exposure to ammonia triggered oxidative stress, and interfered with nutrient absorption and immune function in the small intestinal mucosa of broilers.

Conclusions

These findings have important implications for understanding the toxic mechanisms of ammonia on intestine of broilers, which provides new information that can be used for intervention using nutritional strategies in the future.

Electronic supplementary material

The online version of this article (doi:10.1186/s12953-015-0067-4) contains supplementary material, which is available to authorized users.