title: Antioxidant activity of coumarins and flavonols from the resinous exudate of Haplopappus multifolius.
abstract: The antioxidant activity of eight coumarins and two flavonols isolated from Haplopappus multifolius was studied with the DPPH radical method. Results show that a high concentration of phenolic coumarins and the presence of quercetin and rhamnetin in the exudates could account for the protection of the plant against oxidative stress. Structures for the coumarins 6-hydroxy-7-[(E,E)-3',7'-dimethyl-2',4',7'-octatrienyloxy] coumarin and 7-[(E)-3'-methyl-4'-hydroxy-2'-butenyloxy] coumarin are proposed on the basis of spectroscopic evidence.
authors: Departamento de Ciencias del Ambiente, Fascultad de Química y Biología, Universidad de Santiago de Chile, Avda. Bernardo O'Higgins 3363, Santiago, Chile. rtorres@lauca.usach.cl
authors: René
authors: R
authors: Torres
authors: Francesca
authors: F
authors: Faini
authors: Brenda
authors: B
authors: Modak
authors: Francisco
authors: F
authors: Urbina
authors: Cecilia
authors: C
authors: Labbé
authors: Juan
authors: J
authors: Guerrero