title: High concentrations of aromatic acylated anthocyanins found in cauline hairs in Plectranthus ciliatus.
abstract: Vegetative shoots of a naturalized population of purple-leaved plectranthus (Plectranthus ciliatus, Lamiaceae) were found to contain four main anthocyanins: peonidin 3-(6″-caffeoyl-β-glucopyranoside)-5-β-glucopyranoside, peonidin 3-(6″-caffeoyl-β-glucopyranoside)-5-(6‴-malonyl-β-glucopyranoside), peonidin 3-(6″-E-p-coumaroyl-β-glucopyranoside)-5-(6‴-malonyl-β-glucopyranoside), and peonidin 3-(6″-E-p-coumaroyl-β-glucopyranoside)-5-β-glucopyranoside. The first three of these pigments have not been reported previously from any plant. They all follow the typical anthocyanin pattern of Lamiaceae, with universal occurrence of anthocyanidin 3,5-diglucosides and aromatic acylation with p-coumaric and sometimes caffeic acids; however, they differ by being based on peonidin. The four anthocyanins were present in the leaves (22.2 mg g(-1) DW), and in the xylem and interfascicular parenchyma of the stem. They were exceptionally abundant, among the highest reported for any plant organ, in epidermal hairs on some of the stem internodes (101 mg g(-1) DW). Anthocyanin content in these hairs increased more than three-fold from the youngest to the fourth-youngest internodes. In situ absorbances (λmax ≈ 545 nm) were bathochromic in comparison to absorbances of the isolated anthocyanins in their flavylium form in acidified aqueous solutions (λmax = 525 nm), suggesting that the anthocyanins occur both in quinoidal and flavylium forms in constant proportions in the anthocyanic hair cells. The most distinctive observation with respect to relative proportions of individual anthocyanins was found in de-haired internodes, for which anthocyanin caffeoyl-derivatives decreased, and anthocyanin coumaroyl-derivatives increased, from the youngest to the fourth-youngest internode.
authors.affiliation: Department of Chemistry, University of Bergen, Allégt. 41, N-5007, Bergen, Norway. Electronic address: monica.jordheim@kj.uib.no.
authors.forename: Monica
authors.initials: M
authors.lastname: Jordheim
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand.
authors.forename: Kate
authors.initials: K
authors.lastname: Calcott
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand.
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Gould
authors.affiliation: New Zealand Institute for Plant & Food Research Limited, Private Bag 11-600, Palmerston North, New Zealand.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Davies
authors.affiliation: New Zealand Institute for Plant & Food Research Limited, Private Bag 11-600, Palmerston North, New Zealand.
authors.forename: Kathy E
authors.initials: KE
authors.lastname: Schwinn
authors.affiliation: Department of Chemistry, University of Bergen, Allégt. 41, N-5007, Bergen, Norway.
authors.forename: Øyvind M
authors.initials: ØM
authors.lastname: Andersen
mesh_terms: D000215:Acylation; D000872:Anthocyanins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D003374:Coumarins; D015394:Molecular Structure; D010858:Pigmentation; D018515:Plant Leaves / Q000378:metabolism; D010944:Plants / Q000033:anatomy & histology; D031346:Plectranthus / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000872:Anthocyanins; D003374:Coumarins; C473205:peonidin
keywords: Anthocyanins; Hairs; Identification; Lamiaceae; NMR; Plectranthus ciliatus; Quantification; Trichomes