Structural Studies on Stilbene Oligomers Isolated from the Seeds of Melinjo (Gnetum gnemon L.)

This paper describes the isolation and structural determination of a new stilbene dimer, named 7a- epi -gnetin C, from melinjo ( Gnetum gnemon L.) seed extract. The relative structure was elucidated based on NMR spectroscopic evidence, while the absolute configuration was assigned by a combination of NMR and electronic circular dichroism spectroscopic analysis and chemical conversion. 7a- epi -Gnetin C was evaluated as an antioxidant and was shown to have a comparable activity to the known stilbene oligomers. In addition, the structural revision of gnetin L, a known stilbene dimer, was also discussed.