ANTIOXIDANT ACTIVITY OF POLYPHENOLS FROMHYPOGYMNIA TAVARESIID. HAWKSW. & P. JAMES

Abstract

Recebido em 29/10/2015; aceito em 21/12/2015; publicado na web em 28/03/2016 ANTIOXIDANT ACTIVITY OF POLYPHENOLS FROM HYPOGYMNIA TAVARESII D. HAWKSW. & P. JAMES. Lichen substances have more than one phenolic hydroxyl group attached to one or more benzene rings, thus qualifying them as polyphenols. The secondary metabolites isolated from the lichen H. tavaresii have been studied in a bid to find compounds protective against oxidative stress and free radical-induced damage. The compounds were identified based on their MS and 1 H-NMR spectra as well as retention factors of TLC analysis. In addition to the previously described metabolites (atranorin, chloroatranorin, physodic and physodalic acids) of H. tavaresii, a further three were identified in its thalli: 2´-O-methylphysodone, isophysodic and ursolic acids. The newly identified compounds of H. tavaresii thalli may be useful in the chemotaxonomic classification of this species. Antioxidant effectiveness of the acetone extract's fractions was measured. The compounds of the active fractions were purified and exhibited 180-800 fold less radical scavenging activity than the reference substance α-(+)-tocopherol in a DPPH• model expressed by IC 50 values.

Intramolecular transesterification of depsides yields fluorescent 1H-isochromen-1-ones: Application as a chemical probe for lichen determination

“…* philippe.uriac@univ-rennes1.fr 1 (Elix and Whitton, 1989); 2 (Orange, 2014;Elix et al, 1996, Elix andWardlaw, 1997); 3 (Culberson et al, 1977;Pérez et al, 2016); 4: (Huneck et al, 1970) 587 588…”