Schisphenlignans A–E: Five New Dibenzocyclooctadiene Lignans from Schisandra sphenanthera

Five new dibenzocyclooctadiene lignans, schisphenlignans A-E (1-5), together with eight known ones, were isolated from the stems of Schisandra sphenanthera. The structures of 1-5 were elucidated based on the analysis of their NMR, MS and circular dichroism (CD) spectra. Some isolates were tested for their acute activities on insulin sensitivity in 3T3-L1 differentiated adipocytes, but none of them showed significant bioactivity with 10 µM administration of the tested compounds.