ascorbic-acid and fluorexon

The antioxidant activity of flavonoids may involve their ability to complex body iron in non-redox-active forms. In this study, it was found that the catechol flavonoids rutin and quercetin are able to suppress redox-active labile plasma iron (LPI) in both buffered solution and in iron-overloaded sera. Both flavonoids are effective in loading the metal into the iron-transport protein transferrin. Iron derivatives of quercetin and rutin are able to permeate cell membranes, however, only free quercetin is able to gain access to the cytosol and decrease intracellular labile iron pools. These results suggest that the antioxidant activity of quercetin may be dependent on its ability to shuttle labile iron from cell compartments followed by its transfer to transferrin.

Topics: Animals; Antioxidants; Ascorbic Acid; Binding, Competitive; Cattle; Coordination Complexes; Deferiprone; Ferrous Compounds; Fluoresceins; HeLa Cells; Humans; Iron; Iron Chelating Agents; Oxidation-Reduction; Pyridones; Quaternary Ammonium Compounds; Quercetin; Rutin; Transferrin

Stratum corneum composition and structure limit cutaneous bioavailability of pharmaceutical and cosmetical agents. Electrically assisted transport can increase the rate and extent of delivery; moreover, it also enables the administration of polar and charged molecules into the skin.. The objective of this study was to investigate the effect of electrotreatment on skin permeability by measuring the cumulative delivery of caffeine and sodium ascorbyl phosphate. Furthermore, confocal microscopy was used to visualize the effect of electrotreatment on the penetration of calcein.. Porcine ear skin was used for the in vitro permeation studies, which involved application of either the caffeine or sodium ascorbyl phosphate (NAP) containing gels using the roll-on supplied with the electrotreatment device.. Electrotreatment increased the amount of caffeine and NAP in the skin. Enhancement factors (EF) for NAP of 7.2 and 14.9 were observed following 20 min of electrotreatment and either immediate sampling or a further 60 min of passive diffusion compared with passive diffusion for either 20 or 80 min. The effect on caffeine permeation was less significant (EF = 2.1 for 20 min electrotreatment compared with passive diffusion for 20 min). The confocal microscopy images showed that electrotreatment significantly increased calcein permeation; fluorescence was observed deep into the viable epidermis-reaching depths of up to 60 to 80 microns.. We have shown that electrotreatment increases skin permeability and the cumulative delivery of cosmeticals into the skin.

Topics: Administration, Cutaneous; Analysis of Variance; Animals; Ascorbic Acid; Caffeine; Diffusion; Ear; Electroporation; Fluoresceins; Gels; In Vitro Techniques; Iontophoresis; Microscopy, Confocal; Permeability; Skin; Swine

The fluorescent metal chelating dye calcein is used to obtain an estimate of cellular iron levels and to measure the kinetics of the entry of chelators and chelating drugs into cells. Under reducing conditions in the presence of ascorbic acid, such as that would be present in the cell, the Fe(II)-calcein complex was rapidly formed with a rate constant of 3 x 10(5) M(-1) s(-1). A slower iron-dependent catalytic degradation of calcein also occurred that resulted in the formation of a non-fluorescent calcein product. The Fe(II)-catalyzed degradation of calcein was largely, but not completely, prevented by catalase. Electron paramagnetic resonance spin trapping experiments showed that the Fe(II)-calcein complex promoted formation of hydroxyl or a hydroxyl radical-like species. Together these results indicated that Fe(II) catalyzed the degradation of calcein through both hydrogen peroxide, and to a lesser extent, non-hydrogen peroxide-dependent pathways. The iron-calcein complexes that were responsible for the degradation of calcein were likely high valence oxidizing iron-oxo species such as perferryl or ferryl complexes that were redox cycled by ascorbic acid. Thus, the use of calcein as an intracellular iron-sensing indicator may yield misleading results due to its degradation under certain conditions.

Topics: Ascorbic Acid; Catalase; Catalysis; Chelating Agents; Electron Spin Resonance Spectroscopy; Ferrous Compounds; Fluoresceins; Fluorescent Dyes; Hydrogen Peroxide; Hydroxyl Radical; Iron; Kinetics; Oxidation-Reduction; Spectrometry, Fluorescence