title: Antioxidative compounds from Garcinia buchananii stem bark.
abstract: An aqueous ethanolic extract of the stem bark of Garcinia buchananii showed strong antioxidative activity using H2O2 scavenging, oxygen radical absorbance capacity (ORAC), and Trolox equivalent antioxidant capacity (TEAC) assays. Activity-guided fractionation afforded three new compounds, isomanniflavanone (1), an ent-eriodictyol-(3α→6)-dihydroquercetin-linked biflavanone, 1,5-dimethoxyajacareubin (2), and the depsidone garcinisidone-G (3), and six known compounds, (2″R,3″R)-preussianon, euxanthone, 2-isoprenyl-1,3,5,6-tetrahydroxyxanthone, jacareubin, isogarcinol, and garcinol. All compounds were described for the first time in Garcinia buchananii. The absolute configurations were determined by a combination of NMR, ECD spectroscopy, and polarimetry. These natural products showed high in vitro antioxidative power, especially isomanniflavanone, with an EC50 value of 8.5 μM (H2O2 scavenging), 3.50/4.95 mmol TE/mmol (H/L-TEAC), and 7.54/14.56 mmol TE/mmol (H/L-ORAC).
authors.affiliation: Lehrstuhl für Lebensmittelchemie und Molekulare Sensorik, Technische Universität München , Lise-Meitner-Straße 34, 85354 Freising, Germany.
authors.forename: Timo D
authors.initials: TD
authors.lastname: Stark
authors.forename: Mathias
authors.initials: M
authors.lastname: Salger
authors.forename: Oliver
authors.initials: O
authors.lastname: Frank
authors.forename: Onesmo B
authors.initials: OB
authors.lastname: Balemba
authors.forename: Junichiro
authors.initials: J
authors.lastname: Wakamatsu
authors.forename: Thomas
authors.initials: T
authors.lastname: Hofmann
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D044946:Biflavonoids / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D053630:Depsides / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D044950:Flavanones / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D029760:Garcinia / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000032:analysis; D007783:Lactones / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D024301:Plant Bark / Q000737:chemistry; D013636:Tanzania; D013729:Terpenes / Q000737:chemistry / Q000302:isolation & purification; D044004:Xanthones / Q000737:chemistry / Q000302:isolation & purification
chemical_list: C000600237:1,5-dimethoxyajacareubin; D000975:Antioxidants; D044946:Biflavonoids; D053630:Depsides; D044950:Flavanones; D007783:Lactones; D013729:Terpenes; D044004:Xanthones; C000600238:garcinisidone-G; C000600236:isomanniflavanone; C000875:depsidone; C404221:euxanthone; D006861:Hydrogen Peroxide; C007619:eriodictyol; C054597:garcinol