Flavonoid glycosides and potential antivirus activity of isolated compounds from the leaves of Eucalyptus citriodora

The extraction and solvent partition of the leaves of Eucalyptus citriodora, and repeated column chromatography for n-BuOH fraction yielded a new flavonoid glycoside, citrioside C (1), along with three known flavonoid glycosides (2–4). The latter were identified with kaempferol-3-O-β-d-glucopyranosyl (12)-α-l-rhamnoside (2), kaempferol-3-O-α-l-rhamnoside (3), and quercetin-3-O-α-l-rhamnoside (4). Their chemical structures were identified on the basis of spectroscopic data analyses including NMR, MS, UV, and IR. All constitutents were isolated for the first time from the leaves of Eucalyptus citriodora. The potential antivirus activity of all the isolated compounds was evaluated. Compound 4 showed potent antiviral activity against respiratory syncytial virus with 50% inhibition concentration (IC50) value of 1.9 μg/mL and selective index value of 9.8.