On the autoxidation of bilirubin

Lightner, David A.; Cu, Alexander; McDonagh, Antony F.; Palma, Lucita A.

doi:10.1016/0006-291x(76)90925-6

Cited by 29 publications

(15 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When the computed specific activity ofthe extracted bilirubin was multiplied by the amount of pigment in the dose plus the added carrier, the isotope content of authentic [3H]bilirubin was found to be consistently lower (6.6+0.3%) than the total radioactivity of the injected dose. This difference appeared to be the result of degradation of a small fraction of the added pigment to labeled diazo-negative derivatives (4,38), occurring during the brief period when the pigment was dissolved in 0.1 M NaOH before its addition to serum (4,38,39). A difference between the computed isotope in authentic [3H]bilirubin and total radioactivity was found in all plasma samples collected from intact rats that had been given a tracer pulse of [3H]bilirubin.…”

Section: Analytical Proceduresmentioning

confidence: 91%

“…Before radiobilirubin can be added to serum for injection, the crystalline pigment has to be dissolved in an aqueous solvent at alkaline pH which inevitably results in breakdown of a small amount of the pigment to labeled diazo-negative degradation products of undetermined structure (4,38,39). Although this can be minimized by exclusion of light and by limiting pigment exposure to the alkali to a few seconds, analysis of the injected pigment by the cetrimide extraction procedure and TLC indicated that in the present experiments an average of 6.6% of the radiobilirubin had been degraded in the process ofpreparing it for injection.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Bilirubin kinetics in intact rats and isolated perfused liver. Evidence for hepatic deconjugation of bilirubin glucuronides.

Gollan¹,

Hammaker²,

Ličko³

et al. 1981

J. Clin. Invest.

View full text Add to dashboard Cite

Section: Analytical Proceduresmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Bilirubin kinetics in intact rats and isolated perfused liver. Evidence for hepatic deconjugation of bilirubin glucuronides.

Gollan¹,

Hammaker²,

Ličko³

et al. 1981

J. Clin. Invest.

View full text Add to dashboard Cite

“…Bilirubin is chemically unstable in alkaline solution and undergoes autooxidation (14). Complexed with albumin, the decomposition of bilirubin is slowed down but still occurred under the conditions in the incubator (Fig.…”

Section: Discussionmentioning

confidence: 99%

Bilirubin Toxicity in Neural Cell Lines N115 and NBR10A

1985

View full text Add to dashboard Cite

ABSTRACT. The toxicity of bilirubin was investigated in 2 neural cell lines NBRlOA and N115 using a quantitative dye assay 3-(4,s dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium biomide (MTT) as a measure of cell viability and [%]thymidine incorporation as a measure of DNA synthesis. Short exposures (up to 2 h) to bilirubin, even up to a bilirubin-albumin molar ratio of 1.5, yielded no evidence of toxicity using these assays. At longer exposure times (24 h) a decrease in cell viability and I3H]thymidine incorporation was detected at a molar ratio of 0.8 when the bilirubin concentration was 0.1 m M or higher, whereas lower bilirubin levels a t this molar ratio showed no deleterous effect. The effect of bilirubin is more pronounced a t a molar ratio of 1.5 with longer incubation periods. The M T T assay showed the N115 cells appeared to be more resistant to bilirubin cytotoxicity than NBRlOA cells, a finding which was not obtained from ['Hlthymidine incorporation studies. This discrepancy can be explained by the fact that we are measuring two different variables; the M T T assay estimates the number of viable cells a t the end of the experiment by measuring mitochondria1 function whereas the [%)I]thymidine assay measures the rate of DNA synthesis during the last 2 h of the experiment. The concentration effect of bilirubin is evident from the ['HIthymidine studies in that at a molar ratio of 1.5 and bilirubin concentration of 0.075 m M or higher, there is both cell kill (decrease in DNA) and inhibition of [3H]-thymidine incorporation (decrease in specific activity). When the bilirubin concentration is reduced to 0.03 mM, there is little or no cell death (no change DNA) but inhibition still exists (42% decrease in specific activity).Thus, cell viability and function of these two neural lines is dependent not only on the bilirubin albumin molar ratio, but also on the absolute concentration of bilirubin and albumin as well a s the time of exposure. ciated with irreversible nuclear damage in the brain (kernicterus) (I). The toxic effect of bilirubin in tissue culture cells have been reported in a number of studies including histologic damage in dissociated rat cerebellum (2), decrease in glucose consumption in human fibroblasts (3), decrease in viability and ATP content (4), and increase in potassium leakage in modified L-929 mouse fibroblasts (5). Thaler (6) reported a decrease in DNA synthesis in hepatoma cells. Cell viability in most of these studies was assessed by the exclusion of either trypan blue or erythrocin B. The dyes will only stain those cells which are nonviable and leaky. A qualitative assessment of viable to nonviable cells is usually done by counting under the microscope.T o our knowledge, n o studies have been done on the cytotoxicity of bilirubin on neural cell lines in culture. In the present study, we evaluate the effects of bilirubin in the presence or absence of albumin on cytotoxicity in two established neural cell lines, namely N1 15, a rat neuroblastoma cell and NBRlOA a murine neuroblastoma h...

show abstract

“…[15][16][17][18][19][20][21] High concentrations of 1.1 (UCB) in the blood and bodily tissues leads to serious health problems such as jaundice, athetoid cerebral palsy, and hearing loss or deafness, particularly in newborn infants where the blood-brain barrier is not yet well formed and so may allow bilirubin to enter the brain. 3,15 The beneficial biological effects of BPs and their derivatives have been of mounting interest recently as their potent anti-mutagenicity, 15,18,19,21 and anti-oxidant properties 18,[22][23][24][25][26][27][28] come to light as well as their ability to bind to certain important enzymes.…”

Section: The Biological Properties Of Bile Pigments and Their Derivatmentioning

confidence: 99%

“…Unconjugated bilirubin-IXα (1.1, UCB) is unstable to pH changes and isomerises to bilirubin-III and XIIIin acid and alkaline solutions (Figure 1.6). The process of isomerisation starts with the dissociation of 1.1 (UCB) into four different dipyrrolic units which then randomly reassemble the C10 covalent bond between two symmetrical dipyrrolic units to create symmetric bilirubin-III and XIII 7,16,66,72,73 The photochemical isomers, bilirubin-XIIIWhich exhibit no exo-vinyl groups, are more unstable than bilirubin-IXα which have one exo-vinyl and one endo-vinyl group and bilirubin-III which contain two endo-vinyl group (Figure 1.6). 67 In a similar fashion to 1.1 (UCB), The isomerisation of 1.1 (UCB) in acidic environment in which the protonation of carbons nearby C10 to break the C10-bridge covalent bond and produce four different dipyrrolic units and then randomly reassemble the C10 covalent bond.…”

Section: 59mentioning

confidence: 99%

Physical and chemical interactions between bile pigments and polyaromatic mutagens

Trieu¹

View full text Add to dashboard Cite

A major cause of cancer in humans is exposure to mutagenic compounds. This raises the question of how humans can be protected from these environmental mutagens. Bile pigments (BPs) such as biliverdin, unconjugated bilirubin and protoporphyrin and their derivatives have recently been found to act as antioxidants and inhibit the mutagenic effects of several known environmental mutagens including 2-aminofluorene, benzo [α]pyrene, and 2-amino-1-methyl-6-phenylimido [4,5-b]pyridine. Despite these promising results, very little is known about the mechanisms by which this inhibition is achieved. Understanding these mechanisms would be useful for future drug development. Therefore, this PhD thesis aims to explore physical and chemical interactions between BPs and mutagens. Effects of BPs on the bioavailability and metabolism of mutagens were also examined in vitro using the colorectal adenocarcinoma (Caco-2 cell) monolayer model and the human liver S9 fraction.The physical interactions between mutagens and BPs were examined using three different methods:NMR, UV and effects of bioavailability. The results of the comparison of the NMR spectra of mutagens in the absence and presence of BPs showed very little changes in the chemical shifts of the protons and the changes that did occur were the result of acid/base interactions between the BPs and mutagens. The UV spectrum of each mutagen was measured in the presence and absence of varying concentrations of BPs, and there were no changes to the UV spectra of any of the compounds. Strong physical interactions or aggregation of compounds can also affect their absorption across cell monolayers and so the apparent permeability of mutagens across Caco-2 cell monolayers in the presence and absence of BPs were measured. The results indicated that BPs increased the permeability of the mutagens slightly and effected how much of the compounds remained in tight association with the monolayer but the effects were small. These experiments provided evidence to suggest that physical interactions and aggregations are unlikely to be a major contributing mechanism of the inhibitory effects of BPs on environmental mutagens.Chemical reactions between BPs and the DNA modifying metabolites of mutagens (epoxides) were studied using styrene epoxide as a model for the reactive metabolites. Styrene epoxide is commercially available, stable and less toxic than the reactive metabolites of the mutagens.Competitive reactions were performed in which BPs and their derivatives were placed in solution with guanine and allowed to react with styrene epoxide. These reactions showed that BPs and their dimethyl esters are more reactive to the epoxide than guanine. Bile pigments primarily react through their carboxylic acid groups with the mono-and di-styrene epoxide esters being the major products isolated form the reactions. The pyrrole rings in bilirubin also showed some evidence of iii reaction with styrene epoxide though the products were too unstable to isolate. Thus, it was clear that BPs can effecti...

show abstract

On the autoxidation of bilirubin

Cited by 29 publications

References 18 publications

Bilirubin kinetics in intact rats and isolated perfused liver. Evidence for hepatic deconjugation of bilirubin glucuronides.

Bilirubin kinetics in intact rats and isolated perfused liver. Evidence for hepatic deconjugation of bilirubin glucuronides.

Bilirubin Toxicity in Neural Cell Lines N115 and NBR10A

Physical and chemical interactions between bile pigments and polyaromatic mutagens

Contact Info

Product

Resources

About