Two new neolignans from Gymnotheca involucrata

Two novel biphenyl butyl neolignan derivatives, named gymnothecaneolignans A (1) and B (2), were isolated from the whole parts of endemic medicinal plant of Gymnotheca involucrata (Saururaceae). The structures of the new compounds were elucidated by extensive NMR and MS data, and the absolutely configuration of compound 1 was confirmed by X-ray crystal diffraction analysis.