Two new lignans from Gymnotheca involucrata.

A new dibenzocyclooctdiene (1), and a new eupodienone (2) type lignans were isolated along with five known analogues from the whole plant of Gymnotheca involucrata Pei. The structures of the new compounds were elucidated on the basis of detailed spectroscopic analysis. Bioassay results showed that compounds 1 and 2 exhibited no antimicrobial activity against four Gram-positive bacterial strains and four Gram-negative bacteria at the concentration of 1 mg/mL.