Revalidation and rationale for high pKa values of unconjugated bilirubin

Ostrow, J. Donald; Mukerjee, Pasupati

doi:10.1186/1471-2091-8-7

Cited by 22 publications

(35 citation statements)

References 46 publications

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“…Bilirubin was purified and recrystallized according to McDonagh and Assisi [23]. Its molar extinction coefficient in chloroform (E 453 nm = 56200 L/mol cm) was comparable to the published value [24]. In addition, an HPLC analysis revealed one major peak corresponding to naturally occurring isomer bilirubin IX␣ (92%) and two smaller peaks of isomers bilirubin III␣ (4%) and bilirubin XIII␣ (4%) which are generally present in commercial UCB lots.…”

Section: Preparation and Storage Of Standardsmentioning

confidence: 93%

Highly sensitive method for quantitative determination of bilirubin in biological fluids and tissues

Zelenka

Leníček

Muchová

et al. 2008

Journal of Chromatography B

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Section: Preparation and Storage Of Standardsmentioning

confidence: 93%

Highly sensitive method for quantitative determination of bilirubin in biological fluids and tissues

Zelenka

Leníček

Muchová

et al. 2008

Journal of Chromatography B

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“…Due to the above, these factors are no longer credible/acceptable and pKa values rationalization based on them 13 may be misleading. Moreover, both pKa values estimated in this work are consistent with the low experimental values reported.…”

Section: Discussionmentioning

confidence: 99%

“…In the present study we have evaluated the factors related to the internal hydrogen bonding of UCB proposed by Ostrow and Mukerjee 13 that were used to justify rationally its high pKa values.…”

Section: Discussionmentioning

confidence: 99%

“…4 12, 13 providing a rationalization based on three theoretical factors: (a) the restricted rotation of the -COOH and -COO − group, (b) the effect of breaking the -OH O = C< bond on ionization, and (c) the steric hindrance to solvation of -COO − group, each factor related to the intramolecular H-bonding of UCB. 13 Because of these theoretical factors are based on smaller molecules with structures largely different from UCB, in this article we review the proposed factors through quantum mechanical calculations on the whole UCB molecule to avoid invalid comparisons. Our results provide evidence that the alleged structural factors proposed 13 to account for the higher pKa values are inconsistent with a more rigorous analysis.…”

Section: Introductionmentioning

confidence: 99%

“…13 Because of these theoretical factors are based on smaller molecules with structures largely different from UCB, in this article we review the proposed factors through quantum mechanical calculations on the whole UCB molecule to avoid invalid comparisons. Our results provide evidence that the alleged structural factors proposed 13 to account for the higher pKa values are inconsistent with a more rigorous analysis. Besides, low pKa values were estimated from our calculations.…”

Section: Introductionmentioning

confidence: 99%

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Computational chemical analysis of unconjugated bilirubin anions and insights into pKa values clarification

Vega-Hissi

Estrada

Lavecchia

et al. 2013

The Journal of Chemical Physics

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The pKa, the negative logarithm of the acid dissociation equilibrium constant, of the carboxylic acid groups of unconjugated bilirubin in water is a discussed issue because there are quite different experimental values reported. Using quantum mechanical calculations we have studied the conformational behavior of unconjugated bilirubin species (in gas phase and in solution modeled implicitly and explicitly) to provide evidence that may clarify pKa values because of its pathophysiological relevance. Our results show that rotation of carboxylate group, which is not restricted, settles it in a suitable place to establish stronger interactions that stabilizes the monoanion and the dianion to be properly solvated, demonstrating that the rationalization used to justify the high pKa values of unconjugated bilirubin is inappropriate. Furthermore, low unconjugated bilirubin (UCB) pKa values were estimated from a linear regression analysis.

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Label‐Free Detection of Unbound Bilirubin and Nitrophenol Explosives in Water by a Mechanosynthesized Dual Functional Zinc Complex: Recognition of Picric Acid in Various Common Organic Media

Nair,

Debnath,

Ghosh

et al. 2023

Chemistry A European J

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High levels of unconjugated bilirubin (UB) in serum lead to asymptomatic and neonatal jaundice and brain dysfunctions. Herein, we have reported the detection of UB at as low as 1 μM in an aqueous alkaline medium using a Zn(II) complex. The specificity of the complex has been validated by the HPLC in the concentration window 6–90 μM, which is rare. The sensory response of the probe at physiological pH against nitro explosives developed it as an instant‐acting fluorosensor for picric acid (PA) and 2,4‐dinitrophenol (2,4‐DNP). Spectroscopic titration provided a binding constant of 4×105 M−1 with PA. The naked eye detection was found to be 15 μM. The solid‐state photoluminescent nature of the complex enabled it for PA sensing in the solid phase. Interestingly, the probe remained fluorescent in various volatile and non‐volatile organic solvents. As a result, it can also detect PA and 2,4‐DNP in a wide range of common organic media. NMR studies revealed the coordination of PA, 2,4‐DNP, and UB to the Zn(II) center of the probe, which is responsible for the observed quenching of the probe with the analytes.

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Revalidation and rationale for high pKa values of unconjugated bilirubin

Cited by 22 publications

References 46 publications

Highly sensitive method for quantitative determination of bilirubin in biological fluids and tissues

Highly sensitive method for quantitative determination of bilirubin in biological fluids and tissues

Computational chemical analysis of unconjugated bilirubin anions and insights into pKa values clarification

Label‐Free Detection of Unbound Bilirubin and Nitrophenol Explosives in Water by a Mechanosynthesized Dual Functional Zinc Complex: Recognition of Picric Acid in Various Common Organic Media

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