A new triglycosyl flavonoid isolated from leaf juice of Kalanchoe gastonis-bonnieri (Crassulaceae).
Kalanchoe gastonis-bonnieri R. Hamet & H. Perrier (Crassulaceae) is a succulent species empirically used as a vaginal contraceptive as well as to heal genitourinary infections. A phytochemical study of leaf juice prepared from specimens collected in the flowering season resulted in the isolation of the new flavonoid quercetin 3-O-α-rhamnopyranoside-7-O-β-D-glucopyranosyl-(1-->3)-α-L-rhamnopyranoside, as well as the already known 6-C-β-D-glucopyranosyl- 8-C-β-D-glucopyranosylapigenin (vicenin-2). The NMR spectra of this flavonoid at room temperature exhibited broad and duplicated signals, suggesting the existence of rotameric conformers, which was confirmed by coalescence of the signals at 40°C. The structural elucidation was based on 1H and 13C NMR (HMQC and HMBC) analyses and MS data. This is the first report of a C-glycosyl flavonoid (vicenin-2) in the Crassulaceae family. Additionally, this is the first study in which atropoisomerism has been shown for vicenin-2.
Sônia Soares
SS
Costa
Maria Fernanda Paresqui
MF
Corrêa
Livia Marques
LM
Casanova
D047310:Apigenin / Q000737:chemistry; D029627:Crassulaceae / Q000737:chemistry*; D005419:Flavonoids / Q000737:chemistry*; D005960:Glucosides / Q000737:chemistry; D015394:Molecular Structure; D018515:Plant Leaves / Q000737:chemistry*
D005419:Flavonoids; D005960:Glucosides; C530449:apigenin-6,8-di-C-glycopyranoside; C000598501:quercetin 3-O-alpha-rhamnopyranoside-7-O-beta-D-glucopyranosyl-(1-3)-alpha-L-rhamnopyranoside; D047310:Apigenin