title: Free radical scavengers and antioxidants from Baccharis grisebachii.
abstract: The exudate and seriated extracts from the aerial parts of Baccharis grisebachii (Asteraceae) which is recommended as a digestive and to relieve gastric ulcers in Argentina, showed activity as free radical scavengers and inhibited lipoperoxidation in erythrocytes. Assay-guided isolation led to seven p-coumaric acid derivatives and six flavonoids as the main active constituents of the crude drug. The activity towards the superoxide anion was mainly due to the flavonoid constituents. 5,7,4'-Trihydroxy-6-methoxyflavone and quercetin presented high activity (64 and 79%) even at 12.5 microg/ml. The xanthine oxidase inhibitory effect of the extracts can be related with the p-coumaric acid derivatives drupanin, 4-acetyl-3,5-diprenylcinnamic acid and trans-ferulic acid O-hexan-3-onyl-ether which showed IC(50) values in the range 28-40 microg/ml. Both p-coumaric acid derivatives and flavonoids inhibited lipoperoxidation in erythrocytes. The highest activity was found for the p-coumaric acid derivatives 4-acetyl-3-prenyl-ethoxycinnamate, 3-prenyl-4-(4'-hydroxydihydrocinnamoyloxy)-cinnamate and trans-ferulic acid O-hexan-3-onyl-ether (69-82%) and the flavonoids 5,7,4'-trihydroxy-6-methoxyflavone, quercetin, 5,7,4'-trihydroxy-6,3'-dimethoxyflavone and 5,7,4'-trihydroxy-6,8-dimethoxyflavone (64-84%) at 100 microg/ml. The most active free radical scavengers measured by the DPPH decoloration assay were the p-coumaric acid derivatives drupanin and trans-ferulic acid O-hexan-3-onyl-ether (27-35% at 10 microg/ml) and the flavonoid quercetin (97 and 23% at 10 and 1 microg/ml, respectively). The results support the use of Baccharis grisebachii in Argentinian traditional medicine.
authors.affiliation: Laboratorio de Química de Productos Naturales, Instituto de Química de Recursos Naturales, Universidad de Talca, Casilla 747, Talca, Chile.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Tapia
authors.forename: Jaime
authors.initials: J
authors.lastname: Rodriguez
authors.forename: Cristina
authors.initials: C
authors.lastname: Theoduloz
authors.forename: Susana
authors.initials: S
authors.lastname: Lopez
authors.forename: Gabriela Egly
authors.initials: GE
authors.lastname: Feresin
authors.forename: Guillermo
authors.initials: G
authors.lastname: Schmeda-Hirschmann
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D001118:Argentina; D031175:Baccharis; D002417:Cattle; D002460:Cell Line; D016166:Free Radical Scavengers / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D006801:Humans; D008519:Medicine, Traditional; D035261:Plant Components, Aerial; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D010936:Plant Extracts