ascorbic-acid and terephthalic-acid

Lunar dust toxicity has to be evaluated in view of future manned missions to the Moon. Previous studies on lunar specimens and simulated dusts have revealed an oxidant activity assigned to HO· release. However, the mechanisms behind the reactivity of lunar dust are still quite unclear at the molecular level. In the present study, a complementary set of tests--including terephthalate (TA) hydroxylation, free radical release as measured by means of the spin-trapping/electron paramagnetic resonance (EPR) technique, and cell-free lipoperoxidation--is proposed to investigate the reactions induced by the fine fraction of a lunar dust analogue (JSC-1A-vf) in biologically relevant experimental environments. Our study proved that JSC-1A-vf is able to hydroxylate TA also in anaerobic conditions, which indicates that molecular oxygen is not involved in such a reaction. Spin-trapping/EPR measures showed that the HO· radical is not the reactive intermediate involved in the oxidative potential of JSC-1A-vf. A surface reactivity implying a redox cycle of phosphate-complexed iron via a Fe(IV) state is proposed. The role of this iron species was investigated by assessing the reactivity of JSC-1A-vf toward hydrogen peroxide (Fenton-like activity), formate ions (homolytic rupture of C-H bond), and linoleic acid (cell-free lipoperoxidation). JSC-1A-vf was active in all tests, confirming that redox centers of transition metal ions on the surface of the dust may be responsible for dust reactivity and that the TA assay may be a useful field probe to monitor the surface oxidative potential of lunar dust.

Topics: Ascorbic Acid; Dust; Free Radicals; Health; Hydrogen Peroxide; Hydroxyl Radical; Hydroxylation; Iron; Linoleic Acid; Lipid Peroxidation; Moon; Oxygen; Phthalic Acids; Reactive Oxygen Species; Space Flight; Suspensions

Topics: Antineoplastic Agents; Ascorbic Acid; DNA Cleavage; DNA, Superhelical; Hydrogen Peroxide; Phenanthrolines; Phthalic Acids; Plasmids; Time Factors

Terephthalic acid is used for the production of polyterephthalic acid esters for foils that are applied for cooking, roasting, and baking; it is able to migrate as a monomer into foodstuffs. The effect of sodium terephthalate on vitamins such as thiamin, riboflavin, pyridoxine, and ascorbic acid at different conditions (variation of time and temperature); effects of a foil made of polyterephthalic acid esters was also tested. Thiamin and riboflavin are stabilized by sodium terephthalate while pyridoxine is decomposed faster, especially at higher temperatures. The tests of thiamin and riboflavin in the foils show similar results, whereas the losses of pyridoxine were not so high compared with the tests where sodium terephthalate had been added. Ascorbic acid is protected, too, by sodium terephthalate, except with long heating periods at a temperature of 220 degrees C.

Topics: Ascorbic Acid; Hot Temperature; Phthalic Acids; Polyesters; Pyridoxine; Riboflavin; Thiamine