Cooperative antioxidant effects of ascorbate and thiols with di-tert-butylcatechol during inhibited peroxidation in solution and in sodium dodecyl sulfate (SDS) micelles

Article Abstract:

Ascorbate and thiols have cooperative effects on inhibited peroxidation by di-tert-butylcatechol in solution and in sodium dodecyl sulfate (SDS) micelles. Induction periods for combinations of ascorbyl palmitate (AP) with 3,5,-di-tert-butylcatechol (DTBC) are greater than for DTBC alone. For the combination of DTBC and AP, induction periods are less than for the sum of the periods of each alone. Hydrogen bonding by water on the antioxidant and on the intermediate radical formed in the inhibition step is thought to be responsible. Combinations of the antioxidants may help to inhibit yellowing of paper/pulps with high lignin content.

Research, Wood pulp industry, Production processes, Paper industry, Antioxidants, Antioxidants (Nutrients), Pulp industry

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Peroxidations initiated by lignin model compounds: investigating the role of singlet oxygen in photo-yellowing

Article Abstract:

Peroxidations initiated by lignin model compounds have been investigated relative to the role of singlet oxygen in photoyellowing. Product studies by HPLC from oxidation of methyl linoleate in solution sensitized by 1-(3,4-dimethoxyphenyl-2-(2-methoxyphenoxy)-1-propanone) or 3,5-di-tert-butyl-ortho-quinone and in sodium dodecyl sulfate sensitized by 3,5-di-tert-butyl-ortho-quinone showed a product distribution of 6 hydroperoxides, the four conjugate and 9- and 13-hydroperoxides of some geometrical isomers. Singlet oxygen is implicated in the photoyellowing of high-lignin-content wood pulps.

Canada, Models, Oxidation-reduction reaction, Oxidation-reduction reactions, Photochemical research, Quinone, Quinones, Lignin, Wood-pulp, Wood pulp, Active oxygen

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The reaction of S-nitrosothiols with thiols at high thiol concentration

Article Abstract:

S-nitrosothiols (RSNO) react with corresponding thiols (RSH) present in a 20-fold+ excess easily to give disulfides that correspond. Ammonia and some nitrite anion form. They constitute 90%+ of the nitrogen products in great contrast to the reaction when thiol concentration is low. In that case nitric oxide is the main first nitrogen product. It is quickly changed in oxygen and water to nitrite anion. The reactions have biological consequences of significance in nature and perhaps in medicine, nitorosothiols being potential NO-releasing drugs.

Ammonia, Nitric oxide, Nitrous oxide, Organosulfur compounds, Organic sulfur compounds, Pharmaceutical chemistry, Cardiovascular agents, Nitroso compounds

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