Flavonoids and Triterpenoids from Callistemon citrinus and their inhibitory effect on No production in LPS-Slimulated RAW267.7 Macrophages

Abstract

Phytochemical investigation of the leaves and stems of Callistemon citrinus (Curtis) Skeels led to the isolation of 12 flavonoid and triterpenoid compounds, including one new flavonoid, callistine A (1) and six known flavonoids, 6,7- dimethyl-5,7-dihydroxy-4'-methoxy flavone (2), astragalin (3), quercetin (4), catechin (5), eucalyptin (6), and 8-demethyleucaIyptin (7), along with 5 known triterpenoids, 3-^-acetylmorolic acid (8), 3yỡ-hydroxy-urS'ỉl-en-13(28)-olide (9), betulinic acid (10), diospyrolide (11) and iưsolic acid (12). Theừ chemical structures were determined by analysis of theừ ID- and 2D-NMR and HR-MS data. All isolated compounds were examined for then inhibitory activity against LPS-activated NO production in macrophage RAW264.7 cells. Among them, quercetin (4) and 3jỡ-hydroxy-urs-ll-en-13(28)-olide (9) showed the most potent activities.