title: Purple anthocyanin colouration on lower (abaxial) leaf surface of Hemigraphis colorata (Acanthaceae).
abstract: The functional significance of anthocyanin colouration of lower (abaxial) leaf surfaces is not clear. Two anthocyanins, 5-O-methylcyanidin 3-O-(3″-(β-glucuronopyranosyl)-β-glucopyranoside) (1) and 5-O-methylcyanidin 3-O-β-glucopyranoside (2), were isolated from Hemigraphis colorata (Blume) (Acanthaceae) leaves with strong purple abaxial colouration (2.2 and 0.6mg/gfr.wt., respectively). The glycosyl moiety of 1, the disaccharide 3″-(β-glucuronopyranosyl)-β-glucopyranoside), has previously been reported to occur only in a triterpenoid saponin, lindernioside A. The structural assignment of the aglycone of 1 and 2 is the first complete characterisation of a natural 7-hydroxy-5-methoxyanthocyanidin. Compared to nearly all naturally occurring anthocyanidins, the 5-O-methylation of this anthocyanidin limits the type of possible quinoidal forms of 1 and 2 to be those forms with keto-function in only their 7- and 4'-positions.
authors: Department of Chemistry, University of Bergen, Allégt. 41, 5007 Bergen, Norway.
authors: Irene
authors: I
authors: Skaar
authors: Chemistry Department, Makerere University, P.O. Box 7062, Kampala, Uganda.
authors: Christopher
authors: C
authors: Adaku
authors: Department of Chemistry, University of Bergen, Allégt. 41, 5007 Bergen, Norway.
authors: Monica
authors: M
authors: Jordheim
authors: Chemistry Department, Makerere University, P.O. Box 7062, Kampala, Uganda.
authors: Robert
authors: R
authors: Byamukama
authors: Chemistry Department, Makerere University, P.O. Box 7062, Kampala, Uganda.
authors: Bernard
authors: B
authors: Kiremire
authors: Department of Chemistry, University of Bergen, Allégt. 41, 5007 Bergen, Norway. Electronic address: oyvind.andersen@kj.uib.no.
authors: Øyvind M
authors: ØM
authors: Andersen
mesh_terms: D027901:Acanthaceae / Q000737:chemistry*; D000872:Anthocyanins / Q000737:chemistry / Q000302:isolation & purification*; D005960:Glucosides / Q000737:chemistry / Q000302:isolation & purification*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010860:Pigments, Biological / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: C000594521:5-O-methylcyanidin 3-O-(3'-(beta-glucuronopyranosyl)-beta-glucopyranoside; C000594522:5-O-methylcyanidin 3-O-beta-glucopyranoside; D000872:Anthocyanins; D005960:Glucosides; D010860:Pigments, Biological
keywords: 3″-O-β-Glucuronopyranosyl-β-glucopyranoside; 5-O-Methylcyanidin; Abaxial leaf colouration; Acanthaceae; Anthocyanins; Hemigraphis colorata; Quinoidal forms