linoleic-acid and formic-acid

Magnetite-containing glass-ceramics are promising bio-materials for replacing bone tissue after tumour resection. Thanks to their ferrimagnetic properties, they generate heat when subjected to an alternated magnetic field. In virtue of this they can be employed for the hyperthermic treatment of cancer. Moreover, grafting anti-cancer drugs onto their surface produces specific anti-neoplastic activity in these biomaterials. Gallic acid (GA) exhibits antiproliferative activity which renders it a promising candidate for anticancer applications. In the present paper, the reactivity of ferrimagnetic glass-ceramic SC-45 grafted with GA (SC-45+GA) was studied in terms of ROS release, rupture of the C-H bond of the formate molecule and Fenton reactivity by EPR/spin trapping in acellular systems. The ability of these materials to cause lipid peroxidation was assessed by UV-vis/TBA assay employing linoleic acid as a model of membrane lipid. The results, compared to those obtained with SC-45, showed that GA grafting (i) significantly enhanced the Fenton reactivity and (ii) restored the former reactivity of SC-45 towards both the C-H bond and linoleic acid which had been completely suppressed by prolonged contact with water. Fe

Topics: Biocompatible Materials; Body Fluids; Ceramics; Formates; Gallic Acid; Humans; Hydrogen Peroxide; Iron; Linoleic Acid; Lipid Peroxidation; Magnets; Microscopy, Electron, Scanning; Oxidation-Reduction; Reactive Oxygen Species; Spectrophotometry; Spectroscopy, Fourier Transform Infrared

Free fatty acids bind to beef heart cytochrome c oxidase and induce spectral shifts similar to those obtained with high spin ligands. Oleic (18:1(n-9)) and linoleic (18:2(n-6)) acids induce substantial blue shifts of the Soret peak of oxidized enzyme. Small saturated fatty acids (< 15 carbon atoms) shift the Soret peak to the red, and longer chain acids induce smaller blue shifts. Formate-induced spectral shifts are modified by short chain fatty acids but are unaffected by longer chain fatty acids for which effects are additive with those of formate. Inhibition by formate is partially relieved by all fatty acids tested. Palmitic and linoleic acids increase turnover at low cytochrome c levels and decrease the K(m) for cytochrome c at high cytochrome c levels. Oleic acid protects the enzyme against acid denaturation during turnover. Bovine serum albumin produces a red shift in the oxidase Soret peak and inhibits turnover of the isolated enzyme. Oleic acid and serum albumin modify the electron paramagnetic resonance spectrum of oxidized oxidase, oleic acid shifting the g = 3 (cytochrome a) peak towards low field and albumin towards higher field strengths. The oxidase may possess at least two fatty acid binding sites at one of which cytochrome c binding is modulated and at another spectral changes may be induced. One site is close enough to the binuclear centre to interact allosterically with ligand binding at that centre.

Topics: Animals; Arachidonic Acid; Catalysis; Cattle; Electron Spin Resonance Spectroscopy; Electron Transport Complex IV; Enzyme Activation; Fatty Acids; Formates; Kinetics; Linoleic Acid; Linoleic Acids; Male; Models, Molecular; Myocardium; Oleic Acid; Palmitic Acid; Protein Binding; Protein Conformation; Serum Albumin, Bovine; Spectrophotometry, Atomic