(±)-Involucrasin D, a pair of enantiomeric bisflavonoid from the roots of Shuteria involucrata and its anti-inflammatory activity.

An undescribed bisflavonoid, named involucrasin D ( 1 ), along with two known flavonoids, 2(S)7,3',5'-trihydroxydihydroflavone ( 2 ) and sigmone ( 3 ) were isolated from the roots of Shuteria involucrata . A further chiral separation of 1 to yielded a pair of enantiomers (+)- 1 and (-)- 1 . The structures were elucidated based on spectroscopic analyses and electron circular dichroism (ECD) calculations. Among them, bisflavonoid 1 and its enantiomers displayed remarkable anti-inflammatory effects by inhibiting the production of TNF- α and IL-6 in a dose-dependent manner.