Abstract: AimTo study the chemical components from the bioactive extract of Herpetospermum pedunculosum, a Tibetan medicinal herb for liver diseases. MethodsThe isolation and purification of this extract were conducted by means of silica gels column chromatography and preparative HPLC. The structures of the compounds were elucidated based on their physical and chemical features, and spectral data. ResultsTwo lignans were isolated from this extract. They were elucidated as herpetone (I), dehydrodiconiferyl alcohol (II). ConclusionCompound I is a new compound with the rare structure of sesqui-norlignan. Compound II is isolated from the genus of Herpetospermum for the first time.