Spectroscopic Study on the Interaction between Methylene Blue and Chondroitin 4-Sulfate and Its Analytical Application

Abstract

The interaction of Methylene Blue (MB) with chondroitin-4-sulfate (CHS) has been investigated using spectroscopic techniques, including UV-Vis absorption, Rayleigh resonance scattering (RRS), and circular dichroism (CD). The addition of CHS caused a decrease in the absorbance of MB at 664 nm with a new absorption band appearing at 570 nm, enhanced RRS at 314 nm and 560 nm, and also resulted in an intense CD signal at 568 nm. The Scatchard model has been applied to calculating the binding constant and the number of binding sites. The calculated parameters are consistent with the experimental results. The factors affecting the interaction were investigated. Quantitative spectroscopic methods were developed for the first time. They are based on the fact that a decrease in the absorption at 664 nm and an enhancement of the RRS intensity at 314 nm are proportional to the concentration of CHS added in a certain range. Satisfactory results were obtained on the determination of synthetic samples.

Substitution‐Inert Polynuclear Platinum Complexes as Metalloshielding Agents for Heparan Sulfate

“…The addition of increasing concentrations of FPX to a solution containing MB also resulted in the gradual decrease of MB absorbance (Figure b, left). The association constant between MB and FPX was determined by the Scatchard plot and the value (4.0±0.1×10 4 m −1 ) is two orders of magnitude lower compared with the previously reported association constant between MB and the chondroitin sulfate (CS) polymer (1.73×10 6 m −1 ) . We then studied the effect of metalloshielding on the MB–FPX interaction by adding aliquots of MB to a solution containing FPX pre‐incubated with varying concentrations of PPCs.…”

“…To assess the strength of the noncovalent FPX–PPC interaction for the different compounds in the PPC library, two different competitive inhibition assays were developed (Figure a). The first was based on a spectroscopic investigation of the interaction of methylene blue (MB) with heparin and HS . The second measured the displacement of intercalated ethidium bromide (EtBr) from DNA, which is a useful assay to gauge the relative strengths of coordination compounds to oligosaccharides (heparin/HS) versus oligonucleotides (DNA/RNA) .…”

Inclusion excluded: Chiroptical sensing of the external surface of sulfated cyclodextrins

“…Noticeably, the replacement of the -NH 2 groups with -H, -OH or -OMe substituents completely abolishes the heparan sulfate binding of surfen [15,16]. In addition, electrostatic complexes of basic organic compounds formed with sulfated glycosaminoglycans are highly sensitive to the ionic strength of the solution and dissociate at physiological salt concentration [17,18]. In contrast to this, surfen does bind to sulfated CDXs in the presence of 0.1 M sodium chloride and increse of the Na + concentration up until 1.25 M caused only a small fluctuation of the  max value but did not cancel the UV hypochromism, the spectroscopic sign of CDX association of the drug molecules (Fig.…”

Design and evaluation of matrix-based controlled release tablets of diclofenac sodium and chondroitin sulphate

“…Drug content of DS was analyzed by measuring the absorbance of standard and samples at λ = 275 nm using UV/Visible spectrophotometer (Jasco model V-530, Tokyo, Japan). Drug content of CS was analyzed by using method described by Zhang et al 11 and measuring the absorbance of complex at λ = 662.5 nm and comparing the content from a standard calibration curve. Further the similarity factor (f 2 ) for the release of DS between the test product and that of marketed formulation, Voveran SR (Novartis, Basel, Switzerland), was performed.…”

“…The rate of polymer swelling and dissolution as well as the corresponding rate of drug release are found to increase with either higher levels of drug loading or with use of lower viscosity grades of HPMC. 11 The aim of this study was to develop a controlled release dosage form of DS and CS and to evaluate the drug release kinetics from the HPMC matrix.…”