2078-17-3Relevant 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.
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
