Phenolic Constituents and Antioxidant Activity of an Extract of Anthurium v ersicolor Leaves

Fractionation of a methanolic extract of the leaves of Anthurium versicolor has resulted in the isolation of two main fractions, I and II. Both the extract and the fractions were assayed for their radical-scavenging activity by means of an in vitro test (bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical) and showed a significant radical-scavenging effect. Subsequent chromatographic fractionation of the most active fraction, II, has led to the isolation and characterization, as major constituents, of four new flavone glycosides, acacetin 6-C-[α-l-rhamnopyranosyl-(1→3)-β-d-glucopyranoside] (1), acacetin 6-C-[β-d-xylopyranosyl-(1→6)-β-d-glucopyranoside] (2), acacetin 6-C-[β-d-apiofuranosyl-(1→3)-β-d-glucopyranoside] (3), and acacetin 8-C-[α-l-rhamnopyranosyl-(1→3)-β-d-glucopyranoside] (4), as well as vitexin (apigenin-8-C-β-d-glucopyranoside) and rosmarinic acid. The structures of 1−4 were determined using spectroscopic methods.