Magnolia salicifolia Maxim.
Creators: name: Porter, Elaine A.
name: Kite, Geoffrey C.
name: Veitch, Nigel C.
name: Geoghegan, Ivey A.
name: Larsson, Sonny
name: Simmonds, Monique S. J.
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Magnoliales
Magnoliaceae
Magnolia
Magnolia salicifolia

description: 2.1. Phenolic glycosides detected in tepals of M. salicifolia
LC–UV–MS analysis of an 80% CH 3 OH extract of the tepals of M. salicifolia revealed several abundant UV absorbing components (Fig. 2). The UV and serial mass spectra of these suggested they were phenylethanoid glycosides (1–6) and the flavonol glycoside quercetin 3- O -rutinoside. The latter, together with the 3- O -rutinosides of kaempferol and isorhamnetin, present as minor components of the extract, were identified by the mass spectrometry methods described by Kite and Veitch (2011).
The phenylethanoid glycoside 5 was identified as verbascoside by chromatographic and mass spectrometric comparison with a standard. Verbascoside is an acylated glycoside of 3,4-dihydroxyphenylethanol (= hydroxytyrosol; M = 154), the acylating acid being caffeic acid (M = 180). The presence of these two phenolic moieties in 1–4 was suggested from ion trap MS/MS of their doubly deprotonated molecules [M–2H] 2 —, which gave singly charged fragments at m / z 135.0456 (C 8 H 7 O 2), 161.0248 (C 9 H 5 O 3) and 179.0354 (C 9 H 7 O 4), expected for [(hydroxytyrosol–H 2 O)–H] —, [(caffeic acid–H 2 O)–H] — and [caffeic acid–H] —, respectively. Neither 5 nor 6 generated doubly deprotonated molecules but, following ion trap MS/MS, the singly deprotonated molecule of all of 1–6 showed a neutral loss of C9H5O3 (caffeic acid–H 2 O). Collision cell MS2 spectra of deprotonated 1–6 also gave [(caffeic acid–H 2 O)–H] — as the base ion. The sodiated molecules of 1–6 predominately showed a neutral loss of 146 (Rha) following ion trap MS/MS. Compounds 3, 4 and 6 had molecular masses that were each 146 Da greater than 1, 2 and 5, respectively, and the [(M–Rha) + Na] + ion of 3, 4 and 6 generated by MS/MS fragmented by further rounds of serial mass spectrometry in a similar manner to the sodiated molecules of 1, 2 and 5 (see Sections 3.6–3.13). This suggested that compounds 3, 4 and 6 were rhamnosyl derivatives of 1, 2 and 5, respectively.
During the isolation of 1 and 2, two other phenylethanoid glycosides, 1a and 2a respectively, became apparent. Compounds 1a and 2a were present in the initial extract, eluting just before 1 and 2, respectively (Fig. 2), and their molecular masses were 14 Da less than 1 and 2, respectively. The sodiated molecules of 1a and 2a both lost 132 (pentose residue) to give an ion that fragmented in a similar manner to the [(M–Rha) + Na] + ion of 1 and 2, respectively. This suggested 1a and 2a were analogues of 1 and 2 in which the rhamnose at C-3 0 of the core glucose was replaced by a pentose sugar.
description: Published as part of Porter, Elaine A., Kite, Geoffrey C., Veitch, Nigel C., Geoghegan, Ivey A., Larsson, Sonny & Simmonds, Monique S. J., 2015, Phenylethanoid glycosides in tepals of Magnolia salicifolia and their occurrence in flowers of Magnoliaceae, pp. 185-193 in Phytochemistry 117 on pages 186-187, DOI: 10.1016/j.phytochem.2015.02.025, http://zenodo.org/record/10485999