title: Biosynthesis of the dimeric ellagitannin, cornusiin E, in Tellima grandiflora.
abstract: First evidence for the in vitro synthesis of a dimeric ellagitannin has been obtained with cell-free extracts from the weed Tellima grandiflora (fringe cups, Saxifragaceae). Partially purified enzyme preparations from leaves of this plant catalyzed the oxidation of 1,2,3,4,6-pentagalloyl-beta-D-glucose to the monomeric ellagitannin, tellimagrandin II, followed by oxidative coupling of two units of this intermediate to yield a dimeric derivative. Chemical degradation, MALDI-TOF mass spectrometry, 1H and 13C nuclear magnetic resonance, and CD spectroscopy were employed to identify this enzyme reaction product as cornusiin E which is characterized by a (S)-valoneoyl bridge between glucose-positions 2, 4' and 6'. This result was supported by comparison with data obtained for cornusiin E that had been isolated from leaves of intact T. grandiflora plants. No indication for the earlier proposed existence of rugosin D (an isomer with a 1,4',6'-bound valoneoyl unit) in T. grandiflora has been obtained in this investigation.
authors.affiliation: Molekulare Botanik, Universität Ulm, D-89069 Ulm, Germany.
authors.forename: Ruth
authors.initials: R
authors.lastname: Niemetz
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schilling
authors.forename: Georg G
authors.initials: GG
authors.lastname: Gross
mesh_terms: D019281:Dimerization; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D005960:Glucosides / Q000378:metabolism; D047348:Hydrolyzable Tannins / Q000031:analogs & derivatives* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D014442:Monophenol Monooxygenase / Q000378:metabolism; D010084:Oxidation-Reduction; D018515:Plant Leaves / Q000201:enzymology; D031995:Saxifragaceae / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013634:Tannins / Q000096:biosynthesis* / Q000737:chemistry
chemical_list: D005960:Glucosides; D047348:Hydrolyzable Tannins; D013634:Tannins; C480119:cornusiin E; C013515:ellagitannin; C473299:tellimagrandin II; C435084:pentagalloylglucose; D005707:Gallic Acid; D014442:Monophenol Monooxygenase