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.