New Flavonoid Glucuronate Esters with Anti-inflammatory Activities from Scutellaria regeliana

Two new flavonoid glucuronate esters, named scuregeliosides A and B (1 and 2), as well as three known ones, chrysin-7-O-β-d-glucuronic acid methyl ester (3), 5,7,4'-trihydroxyflavone-8-O-β-d-glucuronic acid methyl ester (4) and apigenin-7-O-β-d-glucuronic acid ethyl ester (5), were isolated from the ethanolic extract of the whole plant of Scutellaria regeliana. Their chemical structures were elucidated on the basis of comprehensive spectroscopic analyses. Five compounds were screened for anti-inflammatory activity in vitro. As the results, the inhibition rates of release of β-glucuronidase from rat polymorphonuclear leukocytes were in the range of 42.2 - 47.1% at a concentration of 10 μm.