Flavonoids from Jovibarba globifera (Crassulaceae) rosette leaves and their antioxidant activity

Seven flavonoids new for the genus Jovibarba, kaempferol 1, kaempferol 3-O-galactopyranosyl-(1 -> 2)-O-alpha-L-rhamnopyranoside 2, kaempferol 3-O-beta-D-glucoside 3, kaempferol 3-O-alpha-L-rhamnopyranosyl-7-O-alpha-D-glucofuranosyl-(1 -> 2)-O-alpha-L-rhamnopyranoside 4, kaempferol 3-O-beta-D-glucopyranoside-7-O-alpha-L-rhamnopyranoside 5, kaempferol 3,7,4'-O-trimethyl ether 6 and quercetin 7, were isolated from fresh and dried leaves of J. ovibarba globifera subsp. globifera. The structures of these compounds were established by analysis of their spectroscopic (H-1 and C-13 NMR) and spectrometric (MS) data, as well as by comparison of these with those reported in the literature. All of the flavonoids are reported for the first time from the investigated taxon. In addition the antioxidant activities in DPPH test of selected compounds were evaluated.