In vitro reducing abilities towards chromate of various hydroxy-containing compounds, including saccharides and their derivatives

Kaiwar, Sharada P.; Raghavan, M. S. S.; Rao, Chebrolu P.

doi:10.1016/0008-6215(94)84224-8

Cited by 22 publications

(3 citation statements)

References 38 publications

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“…The dominance of [Cr(O)( O 3 , O 4 -saH) 2 ] 3- is an excellent example of the preference for Cr(V) to bind to cis - rather than trans -diol groups. This has been illustrated previously on several occasions for Cr(V), , and also for V(IV)-diol binding . Binding via the 4,5-diol group is evident in Cr(V)-qa species, which indicates that the donor properties of the 3,4-diol in saH 4 may be either sterically or electronically enhanced, compared to qaH 5 .…”

Section: Discussionsupporting

confidence: 64%

“…The definitive assignment of the species as a Cr(V)-NADP species, however, is questionable, on the basis of similar g iso and 1 H a iso values observed in EPR spectra formed upon the reduction of Cr(VI) by GSH, in the presence of d -glucose. , More recently, the species formed between Cr(V) and cis - and trans -1,2-cyclohexanediol have been examined using EPR spectroscopy, in an attempt to better understand the species formed between Cr(V) and d -glucose . Because of their potential biological relevance, Cr(V)-sugar complexes have been the focus of several studies and have been characterized by electrochemistry , and EPR 39,41,44-47 and electronic absorption spectroscopies . The effect upon Cr(V) speciation of different intracellular pH values present in phagocytic cells has yet to be thoroughly investigated.…”

Section: Introductionmentioning

confidence: 99%

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Competition between 1,2-Diol and 2-Hydroxy Acid Coordination in Cr(V)-Quinic Acid Complexes: Implications for Stabilization of Cr(V) Intermediates of Relevance to Cr(VI)-Induced Carcinogenesis

Codd

Lay

1999

J. Am. Chem. Soc.

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For the speciation of Cr(V) intermediates formed during the intracellular reduction of Cr(VI) to be understood, the intramolecular competition between 1,2-diol and 2-hydroxy acid coordination to Cr(V) as a function of pH has been studied in quinic acid complexes. The Cr(V)-2-hydroxy acid complex, K[Cr(O)(qaH3)2]·H2O (qaH5 = 1R,3R,4R,5R-1,3,4,5-tetrahydroxycyclohexanecarboxylic acid, I), has been isolated and characterized. In aqueous solutions at pH values <4.0, K[Cr(O)(qaH3)2]·H2O gives two EPR signals (g iso = 1.9787, A iso = 17.2 × 10-4 cm-1; g iso = 1.9791, A iso = 16.4 × 10-4 cm-1). The relative intensities of the signals are independent of [qaH5]/[Cr(V)], and of increasing [qaH5] and [Cr(V)] at constant [qaH5]/[Cr(V)] and pH values. These signals are consistent with those found with well-characterized Cr(V)-2-hydroxy acid complexes and are assigned to two geometric isomers of the [Cr(O)(O 1,O 7-qaH3)2]- linkage isomer. Both the 2-hydroxy acid (O 1,O 7) and vic-diol (cis-O 3,O 4; trans-O 4,O 5) groups of qaH5 are viable Cr(V) donors. In the reduction of Cr(VI) by GSH in the presence of an excess of qaH5, the EPR spectra are similar to that of K[Cr(O)(qaH3)2]·H2O at low pH values (<4.0). At intermediate pH values (pH 5−7.5) additional signals appear (g iso = 1.9791, g iso = 1.9794, g iso = 1.9799), which have EPR spectral data consistent with the presence of Cr(V)-qa linkage isomers, featuring one of each donor type (1 × 2-hydroxy acid; 1 × diol). By using EPR spectral simulation, we deduced that the cis-diol linkage isomer, [Cr(O)(O 1,O 7-qaH3)(O 3,O 4-qaH2)]2-, is an order of magnitude more thermodynamically stable to intramolecular ligand exchange compared to the trans-diol linkage isomer, [Cr(O)(O 1,O 7-qaH3)(O 4,O 5-qaH2)]2-. At pH values >7.5, the Cr(V)-qa EPR spectra reveal two triplets (g iso = 1.9800, g iso = 1.9802), which are ascribed to geometric isomers of a bis-diol Cr(V)-qa complex, [Cr(O)(O 3,O 4-qaH2)2]3-. The concentration of the trans-diol isomer, [Cr(O)(O 4,O 5-qaH2)2]3-, is predicted to be negligible. This assignment is supported by the similarity of the EPR spectral data with those formed in the Cr(VI) reduction by GSH in the presence of the related polyol (cis-O 3,O 4; trans-O 4,O 5) ligand, shikimic acid (3R,4R,5R-3,4,5-trihydroxycyclohexenecarboxylic acid, II), which does not possess a 2-hydroxy acid moiety. The relative intensities of the EPR signals of the Cr(V)-sa species (g iso = 1.9800, g iso = 1.9801), ascribed to geometric isomers of [Cr(O)(O 3,O 4-saH)2]3-, are independent of increasing pH and of [saH4] at pH values >4.0. The results show that 2-hydroxy acid ligands are favored with respect to 1,2-diols for stabilizing Cr(V) at low pH values relevant to phagocytosis of insoluble chromates (pH ∼4), but the opposite is the case when soluble chromates are taken up by the cells at pH = 7.4. Both classes of ligands compete effectively for complexation of Cr(V) compared to glutathione at all pH values studied.

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Section: Discussionsupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Competition between 1,2-Diol and 2-Hydroxy Acid Coordination in Cr(V)-Quinic Acid Complexes: Implications for Stabilization of Cr(V) Intermediates of Relevance to Cr(VI)-Induced Carcinogenesis

Codd

Lay

1999

J. Am. Chem. Soc.

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“…The present study is envisaged to fill this lacuna, and a series of gadolinium oxide nanoparticles coated with different polyols were synthesized. We have used four types of polyols with different reductive abilities, , that is, diethylene glycol (DEG), triethylene glycol (TEG), tetraethylene glycol (TeEG), and polyethylene glycol (PEG 200). The influence of various polyols on the size and morphology of prepared Gd 2 O 3 nanoparticles is presented.…”

Section: Introductionmentioning

confidence: 99%

Effect of Polyol Chain Length on Proton Relaxivity of Gadolinium Oxide Nanoparticles for Enhanced Magnetic Resonance Imaging Contrast

Guleria

Pranjali

Meher³

et al. 2019

J. Phys. Chem. C

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We present the impact of surface modifications on the magnetic resonance imaging (MRI) contrast enhancement abilities of gadolinium oxide nanoparticles. A series of gadolinium oxide nanoparticles surface-coated with polyols of different reductive abilities such as diethylene glycol (DEG), triethylene glycol (TEG), tetraethylene glycol (TeEG), and polyethylene glycol (PEG 200) were synthesized. Particle sizes of synthesized Gd2O3 nanoparticles were found to be in correlation with the chain length of glycol. An enhancement in the in vitro and ex vivo relaxivity of Gd2O3 nanoparticles was revealed with the increase in glycol chain length. Among the various nanosystems, PEG-Gd2O3 has the highest in vitro and ex vivo relaxivities and excellent biocompatibility as revealed from cellular cytotoxicity experiments. The enhancement in MR contrast with glycol chain length can be attributed to the increase in surface hydrophilicity, and its modulation can be exploited as a novel strategy for enhancing the MRI contrast of gadolinium-based contrast agents.

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The EPR Pattern of [CrO(cis-1,2-cyclopentanediolato)2]− and [CrO(trans-1,2-cyclopentanediolato)2]−

Signorella

Daier

Santoro

et al. 2001

Eur. J. Inorg. Chem.

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The addition of a large excess of 1,2-cyclopentanediol to a 1:1 mixture of glutathione and Cr VI at pH 7.5 stabilises the intermediate Cr V species formed by the one-electron reduction of Cr VI by glutathione. The isotropic EPR parameters (g iso and A iso ) of the Cr V species formed with both cis-and trans-1,2-cyclopentanediol correspond to those calculated for five-coordinate oxo-Cr V complexes with four alcoholato

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In vitro reducing abilities towards chromate of various hydroxy-containing compounds, including saccharides and their derivatives

Cited by 22 publications

References 38 publications

Competition between 1,2-Diol and 2-Hydroxy Acid Coordination in Cr(V)-Quinic Acid Complexes: Implications for Stabilization of Cr(V) Intermediates of Relevance to Cr(VI)-Induced Carcinogenesis

Competition between 1,2-Diol and 2-Hydroxy Acid Coordination in Cr(V)-Quinic Acid Complexes: Implications for Stabilization of Cr(V) Intermediates of Relevance to Cr(VI)-Induced Carcinogenesis

Effect of Polyol Chain Length on Proton Relaxivity of Gadolinium Oxide Nanoparticles for Enhanced Magnetic Resonance Imaging Contrast

The EPR Pattern of [CrO(cis-1,2-cyclopentanediolato)2]− and [CrO(trans-1,2-cyclopentanediolato)2]−

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