Cytotoxic Lignans from the Stem Bark of Magnolia officinalis

Three new lignans, 4′-methoxymagndialdehyde (1), 4′-methoxymagnaldehyde B (2), and 4′-methoxymagnaldehyde E (3), were isolated from hexane- and EtOAc-soluble fractions of the stem bark of Magnolia officinalis, together with eight known compounds (4–11). The structures of compounds 1–3 were determined on the basis of spectroscopic and physicochemical data analysis. Compounds 1–11 were tested in vitro for their cytotoxic activity against the K562, HeLa, and A549 cancer cell lines. Among the compounds tested, compound 1 showed the most potent cytotoxic activity against these cancer cell lines, with IC50 values of 3.9, 1.5, and 3.7 µg/mL, respectively.