Sesquiterpene-Neolignans from the Stem Bark of Magnolia obovata and Their Cytotoxic Activity

Three sesquiterpene-lignans, eudeshonokiol B (1), eudesobovatol B (2), and clovanemagnolol (3), were isolated from the stem bark of Magnolia obovata, together with magnolol (4), honokiol (5), and obovatol (6) on the basis of spectroscopic and physicochemical analyses including 2D NMR and Mass. Compounds 1 - 3 were belongs to a unique class of natural products made up of a sesquiterpene and biphenyl-type neolignan via an ether bond. All the isolated compounds were tested in vitro for their cytotoxic activity against the HeLa, A549, and HCTll6 cancer cell lines. Compounds 1 - 6 showed the cytotoxic activity against tested cancer cell lines, with values ranging from 7.1 to 14.4 .