Macrocyclic Compounds with Diverse Skeletons from the Roots of Myrica nana and Their Spasmolytic Activity.

Six undescribed macrocyclic compounds, including diarylhexanoids (1 and 2), a diarylhexanoid glucoside (3), diarylheptanoids (4 and 5), and an aceroside (6), were isolated from the roots of Myrica nana Cheval., along with 11 known analogues (7-17). The structures were elucidated by spectroscopic analysis, as well as by calculated optical rotatory dispersion and derivatization reactions. Metabolites 1-3, with a rare macrocyclic diarylhexane skeleton, differ from the familiar macrocyclic diarylheptanoids. The spasmolytic activity of the isolated compounds was evaluated on acetylcholine-induced contraction of isolated rat ileum. All isolated compounds exhibited significant spasmolytic activities with an EC50 ranging from 1.4 to 5.1 μM. The spasmolytic mechanism of action of compound 1 could be related to the NO production, blockade of muscarinic receptors, K+ efflux, and cytosolic calcium reduction.