Lignans of Chamaecyparis obtusa

Heartwood of Chamaecyparis obtusa contains significant amounts of a dibenzylbutyrolactone lignan,hinokinin (8). This investigation demonstrated that the contents of 8 and a norlignan, hinokiresinol (12), were higher in the heartwood region than in the sapwood, indicating their nature of being heartwood extractives. Eleven lignans - xanthoxylol (1), 7-oxohinokinin (2), savinin (3), dihydrosesamin (4), isoactifolin (5), sesamin (6), piperitol (7), hinokinin (8), pluviatolide (9), haplomyrfolin (10), and matairesinol (11) - were isolated from young shoots of Chamaecyparis obtusa cv. Breviramea. Eight lignans (1, 2,4, 5, 7, 9, 10, and 11) were isolated from this plant for the first time. Chiral high-performance liquid chromatographic analysis showed that 8, 9, 10, and 11, were found to be levorotatory and optically pure (>99% e.e.). Based on the chemical structures of the isolated lignans, possible biosynthetic pathways of 8 are discussed.