Cytotoxic lignans from the twigs of Lindera glauca (Sieb. & Zucc.) Blume var. Glauca

Lindera glauca (Sieb.&Zucc.) Blume var. glauca (Lauraceae) is a small deciduous tree growing in the forests at low altitudes in Japan, China, and Korea. This tree has been used as Korean traditional medicine to treat cancer such as stomach, and lung, and uterine cancer without any side effect. Previous phytochemical studies from the leaves, roots, and stems of this plant have revealed the presence of alkaloids, terpenes, and butanolides. In our continuing search for bioactive constituents from Korean medicinal plants, we investigated the cytotoxic constituents of the twigs of this plant, since the MeOH extract of the source showed significant cytotoxicity against A549, SK-OV-3, SK-MEL-2, and HCT-15 using a sulforhodamine B (SRB) bioassay. A bioassay-guided fractionation and purification of the MeOH extract resulted in the isolation and identification of three new lignans (1-3), along with three known lignans (4-6). The structures of these new compounds were elucidated on the basis of 1D and 2D NMR data as well as CD studies. The isolated compounds were evaluated for cytotoxicity against some human tumor cell lines using a SRB assay.