Equilibrium and kinetic studies on the complexation of boric acid with chromotropic acid

Shao, Changwei; Matsuoka, Shiro; Miyazaki, Yoshinobu; Yoshimura, Kazuhisa; Suzuki, Toshishige M.; Tanaka, David A. Pacheco

doi:10.1039/b004399k

Cited by 23 publications

(23 citation statements)

References 34 publications

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“…The second stage of the reaction is fast in which the second curcumin hydrolyzes in a similar fashion. This mechanism is supported by the earlier report of a two‐stage formation mechanism for the spiroborate esters of chromotropic acid with diols .…”

Section: Resultssupporting

confidence: 84%

Kinetics and Mechanism of the Thermal and Hydrolytic Decomposition Reaction of Rosocyanin

John

Rugmini

Nair

2018

Int J of Chemical Kinetics

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Spiroborate esters of curcumin find applications in the field of medicinal and analytical chemistry. The present paper reports the hydrolytic and thermal stability of rosocyanin, a 1:2 spiroborate ester of curcumin used for the photometric estimation of boron in different matrices. The effect of temperature, pH, and solvents was monitored spectrophotometrically for the hydrolysis of rosocyanin. The reaction followed first‐order kinetics, and the reaction rate enhanced with an increase in the percentage of water in an aqueous organic mixture, temperature, and pH. 11B NMR and UV–visible spectra were used to identify the hydrolysis product. The possible mechanistic route for the hydrolysis of rosocyanin was proposed. Solid‐state stability of rosocyanin was investigated by thermogravimetric analysis, and the data were analyzed using different solid‐state reaction models to find the suitable reaction model. Kinetic parameters associated with its thermal decomposition were calculated using Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose isoconversional methods and were compared.

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Section: Resultssupporting

confidence: 84%

Kinetics and Mechanism of the Thermal and Hydrolytic Decomposition Reaction of Rosocyanin

John

Rugmini

Nair

2018

Int J of Chemical Kinetics

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“…A comparable two‐stage boron‐bridging process has been described for chromotropic acid (CTA; Fig. b) (Shao et al ., ), and the formation of the 1 : 2 (CTA–B (−) –CTA) complex may be a helpful model for studies of RG‐II dimerization. Interestingly, negatively charged groups neighbouring the boron atom can stabilize B‐bridges once formed, as shown in 11 B‐NMR studies of CTA (Shao et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Boron bridging of rhamnogalacturonan‐II is promoted in vitro by cationic chaperones, including polyhistidine and wall glycoproteins

Chormova

Fry

2015

New Phytologist

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Summary Dimerization of rhamnogalacturonan‐II (RG‐II) via boron cross‐links contributes to the assembly and biophysical properties of the cell wall. Pure RG‐II is efficiently dimerized by boric acid (B(OH)3) in vitro only if nonbiological agents for example Pb2+ are added. By contrast, newly synthesized RG‐II domains dimerize very rapidly in vivo. We investigated biological agents that might enable this.We tested for three such agents: novel enzymes, borate‐transferring ligands and cationic ‘chaperones’ that facilitate the close approach of two polyanionic RG‐II molecules. Dimerization was monitored electrophoretically.Parsley shoot cell‐wall enzymes did not affect RG‐II dimerization in vitro. Borate‐binding ligands (apiose, dehydroascorbic acid, alditols) and small organic cations (including polyamines) also lacked consistent effects. Polylysine bound permanently to RG‐II, precluding electrophoretic analysis. However, another polycation, polyhistidine, strongly promoted RG‐II dimerization by B(OH)3 without irreversible polyhistidine–RG‐II complexation. Likewise, partially purified spinach extensins (histidine/lysine‐rich cationic glycoproteins), strongly promoted RG‐II dimerization by B(OH)3 in vitro.Thus certain polycations, including polyhistidine and wall glycoproteins, can chaperone RG‐II, manoeuvring this polyanionic polysaccharide domain such that boron‐bridging is favoured. These chaperones dissociate from RG‐II after facilitating its dimerization, indicating that they act catalytically rather than stoichiometrically. We propose a natural role for extensin–RG‐II interaction in steering cell‐wall assembly.

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“…The formed borate polyanion might play the role of leading ion in EKS. The generation of borate polyanion was already verified in some studies, where the boron complexed with other polyhydroxy compounds . However, there may be another opinion that the better stacking efficiency is caused by the different composition between the two BGEs.…”

Section: Resultsmentioning

confidence: 89%

Electrokinetic supercharging preconcentration prior to CGE analysis of DNA: Sensitivity depends on buffer viscosity and electrode configuration

Mori

Yamada

et al. 2013

Electrophoresis

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Aiming to high sensitivity DNA analysis by CGE, electrokinetic supercharging (EKS) approach was adopted in this article. EKS is known as an online preconcentration technique that combines electrokinetic sample injection (EKI) with transient ITP (tITP). Herein, two factors of buffer viscosity and electrode configuration were studied to further improve EKS performance. An ultralow-viscosity Tris-Boric acid-EDTA (TBE) buffer solution, consisted of 2% low-molecular-weight hydroxypropyl methyl cellulose (HPMC) and 6% mannitol and with pH 8.0 adjusted by boric acid, was applied. The boric acid would make a complex with mannitol and generates borate polyanion, which acts as the leading ion for tITP process. The new electrode configuration, a Pt ring around capillary, was modified on Agilent CE system to lead large amount sample introduction during EKS. The standard DNA sample of φX174/HaeIII digest was used to evaluate the qualitative and quantitative abilities of the proposed strategy. The 170,000-fold highly diluted sample at concentration of 3.0 ng/mL was enriched by EKS and detected by normal UV detection method. The obtained LOD of the weakest peak of 72 bp fragment was around 7.7 pg/mL, apparently improved more than 10,000-fold in comparison with conventional CGE with UV detection.

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Equilibrium and kinetic studies on the complexation of boric acid with chromotropic acid

Cited by 23 publications

References 34 publications

Kinetics and Mechanism of the Thermal and Hydrolytic Decomposition Reaction of Rosocyanin

Kinetics and Mechanism of the Thermal and Hydrolytic Decomposition Reaction of Rosocyanin

Boron bridging of rhamnogalacturonan‐II is promoted in vitro by cationic chaperones, including polyhistidine and wall glycoproteins

Electrokinetic supercharging preconcentration prior to CGE analysis of DNA: Sensitivity depends on buffer viscosity and electrode configuration

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