Kinetics and mechanism of oxidation of chondroitin-4-sulfate polysaccharide by chromic acid in aqueous perchlorate solutions

Sulfated glycosaminoglycans (GAGs) are a family of complex polysaccharides ubiquitously distributed in extracellular matrices and at cell surfaces and playing key roles in a myriad of biological processes. Their structures are based on disaccharide building blocks, usually containing an amino sugar and an uronic acid, decorated with one or more sulfate groups. Many efforts to gain access to a large number of sulfated GAG polysaccharides with potential tailored biomedical applications, usually based on suitable chemical (and chemo-enzymatic) derivatization procedures that modified the native polysaccharide structures, have been reported in the last two decades. In this review we survey such reactions on the basis of (i) the sulfated GAG substrate [(fucosylated) chondroitin sulfate, dermatan sulfate, heparin, and heparan sulfate], and (ii) the sort of structural modification (sulfation pattern modification, oxidation, carboxy group derivatization, N- and O-acylation, reducing-end functionalization)

show abstract

“…Diketone formation on GlcA units was postulated for the oxidation of CS‐A with chromic acid in aqueous perchlorate solution …”

Section: Chondroitin Sulfate Fucosylated Chondroitin Sulfate Andmentioning

confidence: 99%

Chemical Derivatization of Sulfated Glycosaminoglycans

2016

View full text Add to dashboard Cite

show abstract

“…In view of the forgoing arguments and our interest in the oxidation of polysaccharides by various oxidants in both alkaline and acidic media [27][28][29][30][31][32][33][34] in particular by the alkaline hexacyanoferrate(III) as an oxidant [19][20][21] in a series of investigations in our laboratory, we are prompted to undertake the present investigation of oxidation of methyl ester of pectic acid (pectin) by alkaline [Fe(CN) 6 ] 3− with the aim to verify and rectify the errors in derivation of rate-law expression of this redox reaction, which is reported elsewhere, 26 as well as to elucidate a suitable oxidation mechanism consistent with the kinetic results obtained. Again, this investigation aims to shed some light on the nature of electron-transfer mechanism and transition states in the rate-determining step in comparison to that reported for oxidation of the other polysaccharides by this oxidant in alkaline solutions earlier.…”

Section: Introductionmentioning

confidence: 99%

A promising methyl ester of pectic acid polysaccharide in biomedicine and pharmaceutics applications: Oxidation of methyl ester of pectic acid by alkaline hexacyanoferrate(III). A kinetic and mechanistic orientation

Hassan

Ibrahim²

2019

Int J of Chemical Kinetics

Self Cite

View full text Add to dashboard Cite

The oxidation of methyl ester of pectic acid (pectin) (PEC) by a hexacyanoferrate(III) ion at a constant ionic strength of 0.1 mol dm−3 has been investigated spectrophotometrically. The oxidation rates were found to increase with increasing the alkali concentration, indicating that the nature of reaction was base catalyzed. The agreement of [pectin] dependence of the rate constants to the Michaelis‐Menten kinetics proves the formation of 1:1 intermediate complex prior to the rate‐determining step. The deviation of the pseudo–first‐order curves from linearity after 65‐70% of reaction completion indicates the interference of some oxidation products during the reaction progression. The oxidation process was proceeding via a free‐radical intervention mechanism. The activation parameters have been evaluated, and a suitable reaction mechanism is suggested and discussed.

show abstract

“…The oxidation products were identified by elemental analysis and spectral data as described earlier. 9,10…”

Section: Resultsmentioning

confidence: 99%

“…This fact may be attributed to the complex kinetic study of oxidation. However, the kinetics of oxidation of CS by a multiequivalent oxidant such as chromic acid 9 and a one-equivalent oxidant such as hexacyanoferrate(III) 10 has been reported earlier. A lack of information on the nature of the electron-transfer mechanism and transition states in the rate-determining steps for redox systems involving the CS substrate is recognized, which makes the kinetics and mechanistics of the electron-transfer process remains not complete and poor understand.…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Oxidation of Some Sustainable Sulfated Natural Polymers: Kinetics and Mechanism of Oxidation of Water-Soluble Chondroitin-4-Sulfate Polysaccharide by Hexachloroiridate(IV) in Aqueous Solutions

Hassan

Ibrahim

2019

ACS Omega

View full text Add to dashboard Cite

The kinetics and mechanism of hexachloroiridate(IV) oxidation of chondroitin-4-sulfate as a sustainable coordination biopolymer macromolecule (CS) in aqueous acidic solutions at a constant ionic strength of 0.1 mol dm –3 has been investigated spectrophotometrically. Pseudo first-order plots gave sigmoidal curves of S-shape nature, indicating that the kinetics is complex. Two distinct stages have been observed. The first stage was relatively fast corresponding to the autoacceleration period, followed by a slow stage which became linear at a longer time period called the induction period. First-order dependence with respect to the [OX] and fractional first order in [CS] was observed for both stages. Kinetic evidence for formation of the 1:1 intermediate complex within the two stages has been revealed. The influence of [H + ] on the rate constants indicated that the oxidation was of acid inhibition nature. The kinetic parameters have been evaluated, and a suitable reaction mechanism is suggested and discussed in terms of the nature of the electron-transfer process.

show abstract

Kinetics and mechanism of oxidation of chondroitin-4-sulfate polysaccharide by chromic acid in aqueous perchlorate solutions

Cited by 13 publications

References 26 publications

Chemical Derivatization of Sulfated Glycosaminoglycans

Chemical Derivatization of Sulfated Glycosaminoglycans

A promising methyl ester of pectic acid polysaccharide in biomedicine and pharmaceutics applications: Oxidation of methyl ester of pectic acid by alkaline hexacyanoferrate(III). A kinetic and mechanistic orientation

Oxidation of Some Sustainable Sulfated Natural Polymers: Kinetics and Mechanism of Oxidation of Water-Soluble Chondroitin-4-Sulfate Polysaccharide by Hexachloroiridate(IV) in Aqueous Solutions

Contact Info

Product

Resources

About