Sinapic acid trans

Hydroxycinnamic acids possess a C6-C3 skeleton and formally belong to the group of phenylpropanoids. The different compounds present in wine are mainly derived from the hydroxycinnamic acids caffeic acid, p-coumaric acid, ferulic acid, and sinapic acid (Fig. 9C.2). These derivatives can be present in cis- and trans-configured forms, while the trans forms are more stable and therefore more prevalent. In wine HCA are present in low amounts in their free form, while the depside forms, i.e. esters of l-(-i-)-tartaric acid, are predominant. The ubiquitous chlorogenic acids, esters of HCA and quinic acid, cannot be found in wine but are replaced by the tartaric acid esters instead (Ong and Nagel 1978 Singleton et al. 1978 Somers etal. 1987). 

Propenoic acid, 3-(3,5-dimethoxy-4-hydroxyphenyl)-, (E)- trans-sinapic acid 1626 1102, 3748, 3749, 3751 ... 

Ginkgo biloba leaves were extracted and characterized by their phenolic acid profile (protocatechuic, p-hydroxybenzoic, vanillic, cafieic, isovanillic, cis- and trans-p-coutmaic, cis- and Ouns-fenilic, sinapic acid). A C g column (A = 254 nm) and a 73/35 water/methanol mobile phase were used to elute all compounds in 30 min. In general, peak shapes were good, as was overall resolution [403]. 

Cis- and trans-sinapine (the choline ester of sinapic acid), sinapic acid, sinapoyl glucose, Kaempferol-sinapoyl-trihexoside 1 -0-P-D-glucopyranosyl sinapate, Sinapoyl-hexoside, Disinapoyl hexoside, trisinapoyl-dihexoside and sinapoyl conjugate... 

Hydroxycinnamic acids (HCAs) are a major class of phenolic compounds found in nature. They are secondary metabolites derived from tyrosine and phenylalanine, which have a C6-C3 carbon skeleton with a double bond in the side chain that may have a trans or cis configuration (Figure 3.11) [55]. Among the most common and well known HCAs are cinnamic acid, caffeic acid, ferulic acid, m-coumaric acid, o-coumaric acid, p-coumaric acid, and sinapic acid. 

Polyphenols, particularly trans sinapic acid, create dark colour and bitter taste, and also react with proteins, in a similar way like glucosinolates breakdown products. Finally, phytic acid forms complexes both with trace metals, which lower their bioavailability, and with globulins too, which change their IP to low pH values (Kroll, 2007). 

Later, Tressl et al. (1976) also proceeded to the thermic degradation (2 h, 200 JC) of ferulic acid (H.87) and identified the same phenols as Fiddler et al., plus 4-isopropylguaiacol and vanillin alcohol (4-hydroxy-3-methoxybenzenemethanol) which have not been found in coffee. For isoeugenol (H.38), the formula is written as the (E)-( trans -) isomer, but nothing was specified in the text. Tressl et al. (1976) also published the results of thermal decomposition of cinnamic, p-coumaric (H.84) and sinapic (H.90) acids. Many of the simple phenols (and other aromatic compounds) formed have also been identified in roasted coffee volatiles. A thermic fragmentation of quinic acid (E.62) has shown that simple acids, phenols and polyphenols originate from this precursor (Tressl et al., 1978a). 

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