Structure, Photochemistry, and Organic Chemistry of Bilirubin*
Karel P. M. Heirwegh, Stanley B. Brown in Bilirubin, 1982
Oxidative degradation of bile pigments can lead to monopyrrole derivatives. Identification of the derivatives is useful in elucidation of the nature of the pyrrole β-substituents. A particularly useful method is that developed by Rüdiger using dichromatechromic acid to yield cyclic imides and formyl pyrroles.11,12 Bilirubin-IXα with chromic acid would yield the cyclic imide products shown in Figure 9, but so would any of the other isomers of bilirubin, e.g., XIIIα, IXγ, etc. Dichromate oxidation can be more informative. With dichromate, methylvinylmaleimide and the pyrrole dialdehyde (Figure 9) are formed, an observation which would indicate clearly that the bile pigment has at least one central ring with methyl and propionic acid groups, and at least one end ring with methyl and vinyl substituents. Assuming that other cyclic imides and pyrrole d¡aldehydes were incapable of being formed, a tetrapyrrole would have end rings possessing only one methyl and one vinyl group (per end ring) and central rings possessing only one methyl and one propionic acid group per ring. Only the IIIα, IXα, and XIIIα isomers of bilirubin satisfy those criteria. Other oxidative degradation methods have been employed. Alkaline permanganate gives pyrrole-2,5-dicarboxylic acid (from the central rings),13,14 and paraperiodic acid can yield cyclic imides and pyrrole dialdehydes.15
Micronutrients
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Chromium (Cr) is an essential micro-mineral for animals and humans. It is a transition metal that can occur in a number of valence states: 0, +2, +3, and +6. Trivalent chromium (Cr 3+) is the most stable form in biological systems, and cannot be oxidized in tissues to hexavalent (Cr 6+) form which is toxic (4, 6, 8–9). Some roles of chromium in human nutrition are still uncertain, but chromium may act in an organic complex that influences and extends the action of insulin (9). Trivalent chromium (Cr 3+) binds to and activates insulin action, and functions primarily through its role in the regulation of insulin (4, 6, 8–9). Adequate dietary chromium intake may contribute to a normalization of insulin in the body. Chromium (Cr 3+) reduces blood glucose levels in subjects with hyperglycemia, increases low blood glucose concentrations in subjects with hypoglycemia, and has no effect on normal subjects (4). It also functions in carbohydrate, lipid, and nucleic acid metabolism (4). It has been found in nucleoproteins isolated from beef liver and also in RNA preparations (8). Chromium is a cross-linking agent for collagen and may have a role in lipoprotein metabolism, in structure of nucleic acids, and in gene expression (9). Chromium deficiencies may exist particularly in children suffering from protein-calorie malnutrition (8). Chromium poisoning in humans is rare and usually limited to accidental ingestion of hexavalent (Cr6+) chromic acid or chromate (CrO4−2) which is water-soluble and highly toxic (6). Toxicity of hexavalent chrome such as chromate (CrO4−2) to the liver, kidneys, blood, or nervous system are the major causes of death (8).
Environmental toxicants on Leydig cell function
C. Yan Cheng in Spermatogenesis, 2018
Chromium is a heavy metal that is commonly used in industrial processes such as leather tanning operations, metal processing, stainless steel welding, chromate production, and chrome pigment production. When chromium was exposed, it also strongly accumulated in the interstitial cells in rat testis.231 Chromium may also be a Leydig cell toxicant. Exposure to hexavalent chromium (20, 40, and 60 mg/kg BW/day) for 90 days reduced Leydig cell numbers, downregulated Hsd3b1, and decreased testosterone levels.240 In vitro treatment of chromium to TM3 Leydig cells inhibited steroid production in these Leydig cells.241,242
The role of eugenol in the prevention of chromium-induced acute kidney injury in male albino rats
Published in Alexandria Journal of Medicine, 2018
Chromium (Cr) is a heavy metal that has several valence states; the most common one is the hexavalent chromium (CrVI), that is widely used in industries, e.g. leather tanning, stainless steel manufacturing, chrome plating (chromates added as anticorrosive agents to paints, primers, and other surface coatings), welding and wood preservation.1,2 CrVI can also be found in drinking water and in public water systems.3 Environmental and/or occupational exposure to CrVI-containing compounds is known to be toxic and carcinogenic to human beings and animals.4 A major adverse effect of chromium poisoning is nephrotoxicity due to chromium excretion through the kidney, this increases its chromium content and subsequently, nephropathy occurs.5 The toxic manifestations of chromium are considered to be due to oxidative stress.6,7 leading to serious damage to the vital organs.8,9
Assessment of trace element toxicity in surface water of a fish breeding river in Bangladesh: a novel approach for ecological and health risk evaluation
Published in Toxin Reviews, 2022
Md. Refat Jahan Rakib, Yeasmin Nahar Jolly, Bilkis Ara Begum, Tasrina Rabia Choudhury, Konika Jannat Fatema, Md. Saiful Islam, Mir Mohammad Ali, Abubakr M. Idris
The mean concentration of Cd was observed in surface water samples (0.032 mg/L in wet season and 0.04 mg/L in dry season) (Table 2). Slightly higher Cd level was found in dry season which might be due to the variation in water capacity of the river where low water flow in dry season resulted the precipitation of the TEs in water; thereby increasing its concentration (Islam et al. 2014). The dissolved Cr concentration varies from 0.001 to 0.006 mg/L during wet season and 0.019–0.167 mg/L during dry season (Table 2). The highest Cr concentration was obtained at SW4 site for both the season, presumably as a result of the effects from tannery and dyeing industries (Arias-Barreiro et al. 2010). The chromium enrichment of surface water can have been caused by two reasons: (1) natural: concentration of Cr-bearing minerals; and (2) anthropogenic: industrial activities such as tanneries and textile factories which are discharging Cr-based oxidants (chromate, dichromate, etc.) (Facetti et al. 1998). Consequently, the waste discharged from such industries is responsible for elevated Cr level in river water (Mohiuddin et al. 2011, Islam et al.2014).
Toxicity of mixtures of zinc oxide and graphene oxide nanoparticles to aquatic organisms of different trophic level: particles outperform dissolved ions
Published in Nanotoxicology, 2018
Nan Ye, Zhuang Wang, Se Wang, Willie J. G. M. Peijnenburg
Daphnia magna, originally obtained from Jiangmen Hongguang Hi-Tech Biological Co., Ltd (Jiangmen, China), was selected as the test species. The OECD Guideline 202 with slight modifications was used to test the acute toxicity of the studied toxicants to D. magna (OECD, 2004). The toxicity tests were performed using newborn neonates (<24 h old). Five individuals were transferred into a test vial, containing 50 mL of the test toxicants or control. Daphnids were exposed to increasing initial concentrations of the ZnO NPs (from 0.01 to 0.4 mg/L), ZnCl2 (from 0.125 to 8 mg/L), and the GO NPs (from 1 to 80 mg/L). Each exposure concentration was tested with three parallels. Each assay was repeated with different batches of daphnids at three different times and the data presented are the mean of the runs (n = 3). Daphnids were incubated under a 10:14 h light/dark photoperiod (20 ± 1 °C) without feeding during the 48 h exposure period. After 48 h, the immobility was examined by activation of the animals by slightly shaking the test vial and monitoring them for 30 s upon agitation of the suspension. Toxicity of potassium dichromate was assessed as a positive control to strengthen the quality control of the D. magna acute toxicity tests.
Related Knowledge Centers
- Chromium
- Hydrogen Peroxide
- Oxidizing Agent
- Potassium Dichromate
- Pyridine
- Oxyanion
- Oxidation State
- Solution
- Potassium Chromate
- Ether