Lignans from Lonicerae caulis.

A new 2,7`-cyclolignan named lonicerinol (1) along with eight known lignans, (-)-epipinoresinol (2), (-)-pinoresinol (3), 9α-hydroxypinoresinol (4), 7R,8S-dihydrodehydrodiconiferyl alcohol (5), (±)-neo-olivil (6), (+)-isolariciresinol (7), 3-methoxy-8,4`-oxyneoligna-3`,4,7,9,9`-pentol (8), and (-)-pinoresinol 4-O-glucoside (9), were isolated from the caulis of Lonicera japonica THUNB. (Caprifoliaceae). All of these constituents except for (-)-pinoresinol (3) and 9α-hydroxypinoresinol (4) are reported for the first time from the genus Lonicera. The structures and absolute configurations of these compounds were determined on the basis of spectroscopic analysis, including CD and 1D- and 2D-NMR techniques and chemical methods.