A new kavalactone, 4'-hydroxyl dihydro-5, 6-dehydrokavain (1) was isolated from the petroleum ether partition of leaves of Alpinia zerumbet (Pers.) Burtt. et Smith, together with four known kavalactone dimers, rel-1,trans-3-bis-(4-methoxy-2-oxopyran-6-yl)-cis-2,trans-4-diphenyl cyclobutene (2), aniba dimer A (3), aniba dimer C (4), 6,6'-(3,4-diphenylcyclobutane-1,2-diyl)bis(4-methoxy-2H-pyran-2-one (5). The structure of compound 1 was characterized by its MS, 1D-NMR, and 2D-NMR data, and the structures of the known compounds were determined by comparison of their spectroscopic data with those reported by...