Inhibition of fluorescent advanced glycation end products (AGEs) of human serum albumin upon incubation with 3-ß-hydroxybutyrate.

Advanced glycation end products (AGEs), which are the final products of glycation, have a major role in diabetic complication and neurodegenerative disorders. The 3-ß-hydroxybutyrate (3BHB), a ketone body which is produced by the liver, can be detected in increased concentrations in individuals post fasting and prolonged exercises and in diabetic (type I) patients. In this study, the inhibitory effect of 3BHB on AGEs formation by glucose from the human serum albumin (HSA) was studied at physiological conditions after 35 days of incubation, using physical techniques such as circular dichroism and fluorescence spectroscopy, as well as differential scanning calorimetry (DSC). The fluorescence intensity measurements of glycated HSA by glucose (GHSA) in the presence of 3BHB indicate a decrease in AGEs formation. The DSC deconvolution profile results also confirm the protective role of 3BHB on incubated with glucose by preventing the enthalpy reduction of the HSA tail segment, compared with the deconvolution profile seen for incubated with glucose alone. The concentration of 3BHB used in this study is in accordance with the concentration detected in the body of individuals post fasting and prolonged exercises.

Fabrication of a novel iron(III)-PVC membrane sensor based on a new 1,1'-(iminobis(methan-1-yl-1-ylidene))dinaphthalen-2-ol synthetic ionophore for direct and indirect determination of free iron species in some biological and non-biological samples.

In this novel, the iron(III)-PVC membrane sensor was investigated based on a new 1,1'-(iminobis(methan-1-yl-1-ylidene))dinaphthalen-2-ol (IBMYD) synthetic ionophore as a suitable carrier. The best performance was observed for the membrane composition including 33.0% PVC, 65.0% TEHP, 1.0% NaTPB and 1.0% ionophore. The electrode displayed a linear potential response over a wide concentration range from 1.0 x 10(-7) to 1.0 x 10(-1)mol L(-1), with a detection limit of 5.0 x 10(-8)mol L(-1) and a good Nernstian slope of 19.9+/-0.3 mV decade(-1). The sensor possessed some advantages such as short conditioning time, very fast response time (<12s) and especially good discriminating ability towards Fe(III) ions over a wide variety of alkali, alkaline earth, transition, and heavy metal ions. The potential response of the proposed sensor was independent of the pH of the test solution, in the pH working range from 3.0 to 6.3. The fabricated electrode was applied for at least 2 months, without any measurable divergence in the potential characteristics. The optimized sensor was used successfully for direct and indirect determination of free iron species in some different synthetic and real samples with satisfactory results.

First anionic 1,10-phenanthroline-2,9-dicarboxylate containing metal complex obtained from a novel 1:1 proton-transfer compound: synthesis, characterization, crystal structure, and solution studies.

The new 1,10-phenanthroline containing 1:1 proton-transfer compound LH(2), [pyda.H(2)](2+)[phendc](2-), was synthesized from the reaction of 2,6-pyridinediamine, pyda, and 1,10-phenanthroline-2,9-dicarboxylic acid, phendc.H(2), and characterized by elemental analysis, ES-Ms, IR, (1)H, (13)C NMR, and UV/vis spectroscopies. Subsequently, the first example of [phendc](2)(-) containing anionic complex [pyda.H](2)[Co(phendc)(2)].10H(2)O, was prepared, using the above novel proton-transfer compound, and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in the space group P2(1)/n of the monoclinic system with four molecules in a unit cell of dimensions a = 11.877(3) A, b = 31.473(9) A, c = 12.915(4) A, and beta = 116.223(5) degrees. The structure has been refined to a final value for the crystallographic R factor of 0.0524 based on 9021 observed independent reflections. The complexation reactions of pyda, phendc.H(2), and LH(2) with H(+) as well as LH(2) with Co(II) in aqueous solution were investigated by potentiometric pH titrations, and the equilibrium constants for all major complexes formed are described. The results are presented in the form of distribution diagrams revealing the concentrations of individual complex species as a function of pH. The results revealed that, at a pH range of 5.2-6.2, the major complex species is [(pyda.H)](2)[Co(phendc)(2)], similar to the isolated crystalline complex.

Studies on mechanism of 8-methoxypsoralen-DNA interaction in the dark.

The interaction of 8-methoxypsoralen (8-MOP) with calf thymus DNA was studied in darkness at 25 degrees C and pH 7.4. The enthalpy curve for 8-MOP-DNA interaction was obtained by isothermal titration calorimetry and showed a two-step process for the interaction. According to the spectrophotometric data, it was suggested that some compaction may occur in the DNA structure at higher [8-MOP](t)/[DNA] ratio. Using the fluorescence quenching data, the Scatchard analysis was performed for 8-MOP-DNA interaction at the extended ranges of drug concentration. The results indicated that the first set of binding sites was occupied by 1 mol of drug bound per near eight base pairs of DNA. Also 8-MOP caused the quenching of the fluorescence emission of DNA-ethidium bromide complex. The Scatchard analysis of these data indicated the non-competitive manner for quenching. A non-displacement based quenching mechanism has been suggested for this behavior. The circular dichroism spectra also confirmed the non-intercalative binding of 8-MOP at higher concentrations accompanied by some conformational changes in DNA structure. It has been suggested that at low drug load, 8-MOP binds to DNA as an intercalator, which is an endothermic process, whereas at higher ratios of [8-MOP](t)/[DNA], it binds to the outside of DNA, probably in the minor groove and causes some compaction in DNA, which is the exothermic process.