67460-51-9Relevant academic research and scientific papers
Characterization of phenolic compounds in rooibos tea
Krafczyk, Nicole,Glomb, Marcus A.
, p. 3368 - 3376 (2008/09/20)
Polyphenols present in rooibos, a popular herbal tea from Aspalathus linearis, were isolated in two steps. First, phenolic ingredients were separated by multilayer countercurrent chromatography (MLCCC). Preparative high-performance liquid chromatography (HPLC) was then applied to obtain pure flavonoids. The purity and identity of isolated compounds was confirmed by different NMR experiments, HPLC-diode array detector (DAD), or gas chromatography-mass spectrometry (GC-MS) analysis. This strategy proved to be valid to isolate material in up to gram quantities and to verify known and previously not published polyphenol structures. In addition the chemistry of dihydrochalcones and related intermediates was studied. The dihydrochalcone aspalathin was oxidized to the corresponding flavanone-C-glycosides ((R)/(S)-eriodictyol-6-C-β-D-glucopyranoside and (R)/(S)-eriodictyol-8-C- β-D-glucopyranoside). Flavanone-6-C-β-D-glucopyranosides were further degraded to flavones isoorientin and orientin.
Characterization of polyphenols from plant materials through their silylation and 29Si NMR spectroscopy - Line assignment through 29Si, 13C spin-spin couplings
Schraml, Jan,Blechta, Vratislav,Sykora, Jan,Soukupova, Ludmila,Curinova, Petra,Pronek, David,Lachman, Jaromir
, p. 829 - 834 (2007/10/03)
The lines in 29Si NMR spectra of silylated polyphenols and some other compounds are difficult to assign owing to the absence of couplings with protons outside the silyl group. The assignment can be derived through small nJ(29/s
Reactivity of ferulic acid and its derivatives toward hydrogen peroxide and peracetic acid
Pan, George X.,Spencer, Liam,Leary, Gordon J.
, p. 3325 - 3331 (2007/10/03)
The reactions of ferulic acid and its derivatives with hydrogen peroxide and peracetic acid in lignin-retaining bleaching conditions have been investigated to determine their susceptibility to oxidative degradation. The conjugated side chain of ferulic acid and its etherified or esterified derivative was shown to be fairly stable, especially to hydrogen peroxide. The major reaction was trans-cis isomerization that possibly involved a radical mechanism but did not cause bond cleavage. The peracetic acid reaction increased the rate of trans-cis isomerization and was also accompanied by a minor cleavage of the side chain. Esterification did not have a substantial effect on the reactivity of ferulic acid, but 4-O- etherification significantly stabilized it against these two oxidants. By contrast, aldehyde substitution tremendously enhanced the susceptibility of the cinnamyl side chain to oxidative degradation, as evidenced by an intensive degradation of coniferaldehyde.
ASSIGNMENT OF 29Si NMR LINES AND DETERMINATION OF 29Si-13C COUPLING CONSTANTS IN PERTRIMETHYLSILYLATED LIGNIN-RELATED PHENOL-CARBOXYLIC ACIDS BY SELECTIVE HETERONUCLEAR INADEQUATE METHOD
Schraml, Jan,Past, Jaan,Puskar, Jueri,Pehk, Tonis,Lippmaa, Endel,Brezny, Robert
, p. 1985 - 1991 (2007/10/02)
Selective heteronuclear (Si-C) INADEQUATE method has been successfully used to assign all 29Si chemical shifts in six pertrimethylsilylated lignin model compounds.Empirical assignment of the lines in the region δ=23-25 to trimethylsilyl esters of carboxyl
