Dihydrocaffeic acid

A pure culture of the organism was inoculated into a basal medium with the addition of 0.025% caffeic acid. After 7 days incubation at 25°C under conditions of reduced oxygen tension, the caffeic acid was completely metabolized. Metabolites of caffeic acid are identified as dihydrocaffeic acid and ethyl catechol, respectively. In the 1960s, it has been reported that a constitutive enzyme present in strains of Aerobacter decarboxylates caffeic acid to 4-vinylcatechol nonoxidatively [20], Several cinnamic acids have been tested and the decarboxylation product from /7-coumaric acid has been identified as 4-vinylphenol. Thus, the bacterial enzyme activity requires a relatively unhindered 4-hydroxy group on the aromatic ring and an acrylic acid side chain. 

Caffeic acid is reduced to dihydrocaffeic acid, which is dehydroxylated to m-HPPA. In another pathway, caffeic acid can be decarboxylation to yield 4-vinylcatechol which is reduced to 4-ethylcatechol [16,23],... 

Figure 2.6 Summary of main possible interconversions between the different phenolic acids by microbial and mammalian enzymes, starting from dihydrocaffeic acid, the microbial metabolite of 3,4-dihydroxyphenylvaleric acid.

Chlorogenic acid has been used as a name for 5-O-caffeoylquinic acid by the authors of the reports cited except [Monteiro et al., 2007], 3-, 4-, or 5-CQA, 3-, 4-or 5-O-caffeoylquinic acid BA, benzoic acid CA, caffeic acid CLA, chlorogenic acid or 5-O-caffeoylquinic acid dHCA, dihydrocaffeic acid diCQA, dicaffeoylquinic acid FA, ferulic acid FQA, feruloylquinic acid GA, gallic acid HA, hippuric isoFA, isoferulic acid m-CA, ra-coumaric acid ra-HPPA, m-hydroxyphenylpropionic acid p-CA, p-coumaric acid p-HBA, p-hydroxybenzoic acid PPA, phenylpropionic acid. 

Goldstein DS, Stull R, Markey SP, Marks ES, Reiser HR. 1984. Dihydrocaffeic acid A common contaminant in the liquid chromatographic-electrochemical measurement of plasma catecholamines in man. J Chromatogr 311 148-153. 

Moridani MY, Scobie H, Jamshidzadeh A, Salehi P, O Brien PJ. 2001. Caffeic acid, chlorogenic acid, and dihydrocaffeic acid metabolism Glutathione conjugate formation. Drug Metab Dispos 29 1432-1439. 

Poquet L, Clifford MN, Williamson G. 2008a. Investigation of the metabolic fate of dihydrocaffeic acid. Biochem Pharmacol 75 1218-1229. 

A revised structure for the catecholamide spermidine siderophore obtained from Paracoccus denitrificans has been proposed the new structure contains a centrally located oxazole ring (6).3 The soft coral Sinularia brongersmai contains two spermidine derivatives, i.e. (7) and its 10,11-dehydro-derivative [(lOi )], both of which show cytotoxic activity.4 The hypotensive principle of the root bark of Lycium chinense has been isolated as an amorphous alkaloid called kukoamine A.5 Acid hydrolysis of the alkaloid produced only spermine and dihydrocaffeic acid, which, in association with its n.m.r. spectrum, indicated the structure (8). Another hypotensive principle, ephedradine B (9), has been obtained from Ephedra roots.6... 

Kukoamine A (170) was isolated from the crude drug jikoppi, which is prepared from Lycium chinense. Hydrolysis with HC1 afforded two products spermine and dihydrocaffeic acid. Both were identified with authentic samples. The13C-NMR spectrum shows the presence of 14 signals for the 28 carbon atoms. It follows from this observation that kukoamine A must have a symmetric structure hence, there are only two structure possibilities. The H-NMR spectrum shows the presence of only four hydrogen atoms adja-... 

LLE Hexane 60% aqueous MeOH MeOH/H O (1 1 v/v) Tyrosol, 2.3-dihydroxyphenylethanol, oleuropein glycoside, hydroxytyrosol, dihydrocaffeic acid, cinnamic acid, 4-hydroxy-phenylacetic acid, gentisic acid, taxifolin, syringic acid, ferulic acid, luteolin, o-coumaric acid, p-coumaric acid, quercetin, vanillic acid, 4-hydroxy-benzoic acid, caffeic acid, 3,4-dihydroxyphenylacetic acid, gallic acid, and protocatechuic acid UV-vis (200 nm) ESI-MSD CZE-DAD HPLC... 

The fruit, leaves, and root bark of Lycium chinenese (Solanaceae) are used mainly as a tonic. The methanol extract of the root bark of L. chinense is used as an antipyretic and has shown remarkable hypotensive activity in animals. The active components were isolated and were determined to be alkaloids, named kukoamines A and B [5,6]. Kuko is the Japanese name for L. chinense. These alkaloids are composed of a spermine unit and two molecules of dihydrocaffeic acid, as in the case of the ephedradines described above. The total synthesis of kukoamine A was independently achieved by two groups [7,8]. 

The action of catechol O-methyl transferase might be a central metabolic event after the absorption of free caffeic acid or some of its metabolites with a still intact catechol moiety, such as dihydrocaffeic acid or protocatechuic acid. In most studies administering chlorogenic acid or preparations rich in caffeic acid derivatives (i.e., coffee), only 0-methylated metabolites but no metabolites with an intact catechol group were detected in urine, supporting the central role of 0-methylation of caffeic acid post absorption [6,17,18]. Studying the O-methylation of caffeic acid in vitro by using rat or rabbit liver slices or preparations of liver, both possible O-methylation products, ferulic and iso-femlic acids, were formed, and a meta/para ratio of 2.8 1 was recorded [13]. In addition, the ability to reduce the residual double bond was also observed in vitro with rat or rabbit liver slices [10]. 

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