A Novel Acylated Quercetin Tetraglycoside from Oolong Tea (Camelia sinensis) extracts.

Abstract

A Novel Acylated Quercetin Tetraglycoside from Oolong Tea (Camelia sinensis) extracts. -(MIHARA, R.; MITSUNAGA*, T.; FUKUI, Y.; NAKAI, M.; YAMAJI, N.; SHIBATA, H.; Tetrahedron Lett. 45 (2004) 26, 5077-5080; Fac. Bioresour., Mie Univ., Tsu, Mie 514, Japan; Eng.) -Mais 42-221

Structural Annotation and Elucidation of Conjugated Phenolic Compounds in Black, Green, and White Tea Extracts

“…To fully identify these complex conjugates, we trapped them using mass-based SPE and subsequently obtained almost pure NMR spectra for three of them (Figure ). The SPE-NMR fraction of the C 47 H 53 O 27 isomer eluting at RT 38.11 min yielded NMR signals that were in very good agreement with those previously reported for quercetin-3- O -(2G- p -coumaroyl( trans )-3G- O -β- l -arabinosyl-3 R - O -β- d -glucosylrutinoside (Figure A). Additional 2D- 1 H COSY experiments confirmed its structure.…”

“…Currently, there is no single experimental database that provides all chemical knowledge of a sample, which hampers a fast identification based on a combination of observed retention time, UV absorption, MS spectra, and NMR signals. For example, the acylated quercetin tetraglycoside with observed [M – H] − mass of 1033.2827 was already identified in an oolong tea extract in 2004, but was not fully annotated in later studies, most likely due to limited structural information . We have previously shown that our HPLC-MS-SPE-NMR approach enabled structural elucidation of quercetin and kaempferol glycosides, including several isomers .…”

“…This shows that the combination of LC-MS n and HPLC-MS-SPE-NMR platforms enables the analysis of small amounts of compounds present in a highly complex extract such as tea. For unambiguous identification we currently used 100 mg of dried tea product, which is much less than in other tea metabolite identification studies taking a few grams up to kilograms of plant sample. ,,, In fact, for a few metabolites, depending upon their ionization efficiency in negative electrospray ionization mode and the intensity of specific NMR signals obtained within the 15 min of scan time, we needed <2 μg of compound for full structural characterization.…”

“…Moreover, the p -coumaroyl cis isomer of kaempferol was trapped at even a much lower amount (about 0.2 μg); nevertheless, full identification of this molecule was possible due to the high similarity of its MS n fragmentation patterns (Figure ) and NMR signals (Figure ) with its trans isomer and the observation of the diagnostic α proton of the p -coumaroyl moiety at lower ppm resonance (5.93 vs 6.38 ppm) and a smaller coupling constant (13 vs 16 Hz), as was seen in related acylated quercetin glycosides . Literature data also reported the presence of more of these complex conjugates in tea based on LC-MS, , as well as NMR. , In our study, 1D- 1 H NMR spectra were needed to fully unravel and confirm their structures and enable MSI level 1 annotations.…”

Extraction behavior of caffeine and EGCG from green and black tea

“…Plant extracts have been widely used as topical applications for wound-healing, anti-aging, and disease treatments. Teas are classified into three major categories based on how they are manufactured as follows: (a) unfermented green tea, (b) partially fermented Oolong tea, and (c) fully fermented black tea [7,8]. Catechins (EGCG) and alkaloids (caffeine), the main active ingredients in green tea, have been proven to have a variety of physiological functions, such as protecting against cancers of the duodenum, colon, skin, lung, breast, esophagus, pancreas, and prostate.…”