title: Phenylethanoid glycosides in tepals of Magnolia salicifolia and their occurrence in flowers of Magnoliaceae.
abstract: Phenylethanoid glycosides were among the major UV-absorbing components in 80% aq. CH3OH extracts of the tepals of Magnolia salicifolia (Siebold & Zucc.) Maxim. (Magnoliaceae; Magnolia subgenus Yulania). Structural characterisation of isolated compounds by spectroscopic and chemical methods revealed three previously unrecorded examples, yulanoside A, yulanoside B and 2'-rhamnoechinacoside, and the known compounds echinacoside and crassifolioside; chromatographic methods also identified verbascoside in the tepal extract. Yulanoside A is the first reported example of a phenylethanoid pentaglycoside, namely hydroxytyrosol 1-O-{β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-[3,4-dihydroxycinnamoyl-(→4)][α-L-rhamnopyranosyl-(1→3)][α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside}. A survey of Magnolia sensu lato and Liriodendron (the two genera of Magnoliaceae) suggested that yulanoside A and its deglucosyl derivative (yulanoside B) were a feature of the tepal chemistry of Magnolia subgenus Yulania (except Magnolia acuminata, the sole member of section Tulipastrum, which did not accumulate phenylethanoid glycosides). The two species of Liriodendron and examined examples of Magnolia subgenus Magnolia sections Magnolia and Rytidospermum (subsection Oyama) also accumulated phenylethanoid glycosides in their tepals and in these species, and in subgenus Yulania, the major compounds were one or more of echinacoside, 2'-rhamnoechinacoside, crassifolioside and verbascoside. Levels of phenylethanoid glycosides were found to be much lower in species studied from Magnolia sections Gwillimia, Macrophylla and Rytidospermum (subsection Rytidospermum), although yulanoside A was detectable in M. macrophylla and this may have some bearing on the placement of section Macrophylla, which is currently uncertain. In the isolates of yulanoside B and echinacoside, minor phenylethanoid glycosides were determined to be analogues of these compounds with β-D-xylose at C-3' of the primary glucose rather than α-L-rhamnose.
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
authors.forename: Elaine A
authors.initials: EA
authors.lastname: Porter
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
authors.forename: Geoffrey C
authors.initials: GC
authors.lastname: Kite
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
authors.forename: Nigel C
authors.initials: NC
authors.lastname: Veitch
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK; Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
authors.forename: Ivey A
authors.initials: IA
authors.lastname: Geoghegan
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK; Natural History Museum Denmark, Solvgade 83, DK-1307 Copenhagen, Denmark.
authors.forename: Sonny
authors.initials: S
authors.lastname: Larsson
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK. Electronic address: m.simmonds@kew.org.
authors.forename: Monique S J
authors.initials: MSJ
authors.lastname: Simmonds
mesh_terms: D035264:Flowers / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry / Q000302:isolation & purification*; D029562:Magnoliaceae / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000737:chemistry / Q000302:isolation & purification; D014994:Xylose
chemical_list: D006027:Glycosides; C000606575:yulanoside A; C005975:3,4-dihydroxyphenylethanol; D014994:Xylose; C060297:echinacoside; D010626:Phenylethyl Alcohol
keywords: Chemosystematics; Flower; Liriodendron; Magnolia salicifolia; Magnoliaceae; Phenylethanoid glycosides; Yulanoside A