Sinapic acid oxidation

Takahama, U. Oniki, T. Effects of ascorbate on the oxidation of derivatives of hydroxycinnamic acid and the mechanism of oxidation of sinapic acid by cell wall-bound peroxidases. Plant Cell Physiol. 1994, 35, 593-600. 

In the first category the best known cases are those in which a hydroxycinnamic acid is dimerized oxi< datively to a bisaryldilactone. A range of examples are known.Typical reactions are the oxidation of sinapic acid (273) to the dilactone (274), in 65% yield using oxygen-iron(III) chloride, and in 60%... 

In the case of sinapic acid (39), the CV data indicate that the oxidation potential at the initial step is almost comparable to that at the second step. On controlled potential... 

Iron(III) oxides, especially hematite, Fc203, were found to catalyze the oxidation of the common soil phenolic acids, sinapic acid (29), and (to a lesser extent) ferulic acid (30 Lehmann et al., 1987). Salicylic acid (31), while strongly bound by iron oxide, was resistant to oxidation (McBride, 1987). 

Fig. 9 Beautiful colours obtained after laccase/peroxidase oxidation of different iignin monomers (2,6-dimethoxyphenol, syringaldazine, sinapic acid, cafeic acid, respectiveiy)...

The most common unsaturated aromatic carboxylic acid is cinnamic acid (8-73). In cinnamon and other spices the (E)-isomer predominates. Cinnamic acid oxidation products are 4-hydroxycinnamic acid (also known as 4-coumaric or p-coumaric acid) and 3,4-dihydroxycinnamic acids, which is called caffeic acid. A 3-methoxy derivative of caffeic acid is feruhc acid and the 3,5-dimethoxy derivative is known as sinapic acid. 

Some eggs may have an unusual or unacceptable odour or taste, although their appearance is normal. The cause may be age (they are past their best ), high storage temperatures, or poor storage conditions, resulting in fishy or other undesirable flavours. The fishy off-flavour, more common in brown-shelled eggs, is caused by the presence of trimethylamine that is produced by microbial decomposition of choline when hens are fed excessive amounts of fishmeals or fish oils and rapeseed and mustard meals. In the case of oilseed meals, trimethylamine arises from sinapine, an ester of choline with sinapic acid. In most breeds of hens, trimethylamine is enzymatically oxidised to odourless trimethylamine oxide, which is excreted from the body. 

Koski A, Pekkaiinen S, Hopia A, Wahala K, Heinonen M. 2003. Processing of rapeseed oil Effects on sinapic acid derivative content and oxidative stability. European Food Research and Technology, 217 110-114. 

Yun KJ, Koh DJ, Kim SH, Park S J, Ryu JH, Kim DG, Lee J Y, Lee KT. 2(X)8. Anti-inflammatory effects of sinapic acid through the suppression of inducible nitric oxide synthase, cyclo-oxygase-2, and pro inflammatory cytokines expressions via nuclear factor-kB inactivation. Journal of Agricultural and Food Chemistry, 56 10265-10272. 

Evaluation of the fractionated and non-fractionated 70% methanolic rapeseed meal extract added to stripped rapeseed oil at a concentration that was equivalent to 500 pmol/kg oil of total phenolic compounds (as quantified by HPLC, 330 nm) was compared with sinapic acid. The fractionated free-phenolic compounds (free-phenolic fraction), which contain over 85% sinapic acid, showed a similar pattern with the sinapic acid standard with respect to the inhibition of both the hydroperoxides and propanal in the emulsion. This was observed for both the cases, that is, hydroperoxide inhibition and propanal inhibition. The effectiveness of the fractionated free-phenolic componnds (free-phenolic fraction) may be dne to the high concentration of sinapic acid in the extracts. These extracts, when added to a 10% o/w system at a concentration of 500 pmol/kg oil exhibited differences in the potencies with respect to inhibition of the primary and secondary prodncts of oxidation. 

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