Naturally occurring 5-lipoxygenase inhibitor. II. Structures and syntheses of ardisianones A and B, and maesanin, alkenyl-1,4-benzoquinones from the rhizome of Ardisia japonica

New alkenyl-1,4-benzoquinones, ardisianones A (1) and B (2), and the known maesanin (3) as 5-lipoxygenase inhibitors have been isolated from the rhizome of Ardisia japonica. Their structures have been elucidated as 2-methoxy-6-[(Z)-10'-pentadecenyl]-1,4-benzoquinone and 5-hydroxy-2-methoxy-6-[(Z)-8'-tridecenyl]-1,4-benzoquinone, respectively, on the basis of spectroscopic data and chemical degradation. Ardisianone A (1), maesanin (3) and belamcandol A (7) have been synthesized starting from belamcandol B (6), readily prepared by Wittig reaction between 9-(2-tetrahydropyranyloxy)nonanal and 3,5-dimethoxybenzyltriphenylphsophonium bromide followed by selective demethylation with sodium thioethoxide.