title: Isolation and structure elucidation of radical scavengers from Thymus vulgaris leaves.
abstract: 2,2-Diphenyl-1-picrylhydrazyl radical (DPPH*) scavenging activity-guided fractionation of a leaf extract of Thymus vulgaris led to the isolation of the radical scavengers rosmarinic acid 1, eriodictyol, taxifolin, luteolin 7-glucuronide, p-cymene 2,3-diol, p-cymene 2,3-diol 6-6'-dimer, carvacrol, thymol, and a new compound, 2. The fractionation was considerably facilitated by using an on-line HPLC detector for radical scavenging activity. In this detector activity is monitored as the disappearance of the color of a postcolumn added stable radical after reacting with radical scavengers in a reaction coil. Compound 2, which consists of rosmarinic and caffeic acid moieties linked via a C-3'-C-8' ' ether bridge, was mainly elucidated by various NMR techniques and CD. Phenylpropanoid trimer 2 was a weaker and stronger radical scavenger than rosmarinic acid 1 in off-line TEAC and DPPH* assays, respectively.
authors.affiliation: Laboratory of Organic Chemistry, Phytochemical Section, Wageningen University, Dreijenplein 8, 6703 HB Wageningen, The Netherlands.
authors.forename: Airidas
authors.initials: A
authors.lastname: Dapkevicius
authors.forename: Teris A
authors.initials: TA
authors.lastname: van Beek
authors.forename: Gerrit P
authors.initials: GP
authors.lastname: Lelyveld
authors.forename: Albertus
authors.initials: A
authors.lastname: van Veldhuizen
authors.forename: Aede
authors.initials: A
authors.lastname: de Groot
authors.forename: Jozef P H
authors.initials: JP
authors.lastname: Linssen
authors.forename: Rimantas
authors.initials: R
authors.lastname: Venskutonis
mesh_terms: D001713:Biphenyl Compounds; D002851:Chromatography, High Pressure Liquid; D002934:Cinnamates / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D000081007:Cymenes; D053630:Depsides; D044948:Flavonols; D016166:Free Radical Scavengers / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D008097:Lithuania; D008968:Molecular Conformation; D015394:Molecular Structure; D039821:Monoterpenes; D010851:Picrates / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*; D011794:Quercetin / Q000031:analogs & derivatives*; D013329:Structure-Activity Relationship; D013729:Terpenes; D046930:Thymus Plant / Q000737:chemistry*; D000097123:Rosmarinic Acid
chemical_list: D001713:Biphenyl Compounds; D002934:Cinnamates; D000081007:Cymenes; D053630:Depsides; D044948:Flavonols; D016166:Free Radical Scavengers; D039821:Monoterpenes; D010851:Picrates; D011794:Quercetin; D013729:Terpenes; D000097123:Rosmarinic Acid; C464738:3'-O-(8''-Z-caffeoyl)rosmarinic acid; C073316:carvacrol; C003377:taxifolin; C004931:1,1-diphenyl-2-picrylhydrazyl