Antioxidant Mechanism of Carnosic Acid:  Structural Identification of Two Oxidation Products

Abstract

To determine the antioxidant mechanism of food phenolics against the oxidation of food components, the reaction of carnosic acid, an antioxidative constituent of the popular herbs sage and rosemary, was investigated in the presence of ethyl linoleate and the radical oxidation initiator 2,2'-azobis(2,4-dimethylvaleronitrile). During this process, carnosic acid was oxidized to an o-quinone and a hydroxy p-quinone, the chemical structures of which were confirmed by physical and chemical techniques. From a quantitative time course analysis of the production of these quinones, an antioxidant mechanism of carnosic acid is proposed, consisting of the oxidative coupling reaction with the peroxyl radical at the 12- or 14-position of carnosic acid and subsequent degradation reactions.

Carnosic acid biosynthesis elucidated by a synthetic biology platform

“…S3A, b, S19, and S20). The remaining compound in this group could result from oxidative degradation and rearrangement of carnosic acid to a molecule bearing a catechol, quinone, or semiquinone feature at C-12-C-11 (13,43,44), but insufficient amounts precluded characterization at this stage. The last group of compounds displayed 343 m/z as the most abundant fragment ion (SI Appendix, Fig.…”

Supplementation of Rosemary extract in the diet of Nero Siciliano pigs: evaluation of the antioxidant properties on meat quality

“…This could be due to the concentration of the extract added, which was not sufficient to improve the shelf life of the meat. Probably, a significant loss of phenolic compounds occurred as lipid oxidation progressed, a finding of which may be understood on the basis of antioxidative activity and concomitant degradation of the phenolic compounds due to the development of free radicals in the primary stage of oxidation (radical trapping stage) during the chain-breaking antioxidant process (Masuda et al, 2001).…”

“…A primary mechanism for a phenolic antioxidant includes the trapping and stabilizing of species generated from the radical chain oxidation of food components. Although the first stage (radical trapping stage) is a reversible process, the second stage (radical termination stage) is irreversible and must produce stable radical termination compounds (Masuda et al, 2001), thus terminating the chain reaction and preserving PUFAs by the synthesis of hydroperoxides (Chen et al, 1992). Another explanation could be that the rosemary extract increases the activity of the delta-5 desaturase (Δ5d) and delta-6 desaturase (Δ6d), which are the enzymes involved in the synthesis of 20:5n-3 and 22:6n-3 derived from the 18:3n-3 (Mourot, 2009).…”

Analysis of the influence of rosemary and grape seed extracts on oxidation the lipids of peking duck meat

“…Внесение композиции в фарш из мяса утки позволяет замедлить гидролитическое и перекисное окисление липидов. Полученные результаты доказывают перспектив-ность использования композиций в техно-логии фаршевые изделий с высоким содер-жанием жира Ключевые слова: окисление липидов, экcтракт розмарина, виноградные косточ-ки, кислотное число, перекисное число UDC 637.5.05/07 DOI: 10.15587/1729-4061.2017.108851 organoleptic properties of meat products, and it prolongs their shelf life [4].…”

“…However, concern about the safety of these substances has given rise to a number of studies of new natural sources of antioxidants for delayed oxidative degradation of lipids [1,2,[4][5][6].…”