Identification and characterization of proanthocyanidins of 16 members of the Rhododendron genus (Ericaceae) by tandem LC-MS

摘要: The proanthocyanidins of the leaves 16 taxa Rhododendron genus (Ericaceae) [Rhododendron 'Catawbiense Grandiflorum', 'Cunningham's White', smirnowii Trautv., calophytum Franch., dichroanthum ssp. scyphocalyx (Balf. f. & Forrest ) Cowan, micranthum Turcz., praevernum Hutch., ungernii kaempferi Planch., degronianum heptamerum var. hondoense (Nakai H. Hara, fortunei Lindl., ponticum L., galactinum Balf. ex Tagg., oreotrephes W. Sm., brachycarpum D. Don G. Don, and insigne Hemsl. E. Wilson ] were investigated qualitatively by liquid chromatography-mass spectrometry in series. Twenty-nine dimeric based on (epi)catechin (epi)gallocatechin detected characterized basis their unique fragmentation pattern negative ion mode tandem mass spectra. All them extracted for first time from these sources, ten not reported previously nature. position galloyl residue was assigned retro-Diels-Alder dehydrated fragmentation; it resulted loss gallic acid as a neutral mode. Furthermore, four caffeoylquinic acids, six p-coumaroylquinic epigallocatechin, gallocatechin, catechin, epicatechin, epigallocatechin gallate, catechin epicatechin gallocatechin two quercetin-O-hexosides, quercetin-O-galloyl-hexoside, quercetin-O-pentoside, quercetin-O-rhamnoside, quercetin-O-pentoside-O-hexoside, quercetin-O-rhamnoside-O-hexoside, quercetin-O-feruloyl-hexoside, quercetin-O-(p-hydroxy)benzoyl-hexoside, taxifolin-O-pentoside, myricetin-O-rhamnoside, myricetin-O-pentosides, three myricetin-O-hexosides, myricetin-O-galloyl-hexosides shown to possess characteristic spectra tentatively retention time.