Macrocyclic Compounds with Diverse Skeletons from\nthe Roots of <i>Myrica nana</i> and Their Spasmolytic Activity

Six\nundescribed macrocyclic compounds, including diarylhexanoids\n(<b>1</b> and <b>2</b>), a diarylhexanoid glucoside (<b>3</b>), diarylheptanoids (<b>4</b> and <b>5</b>),\nand an aceroside (<b>6</b>), were isolated from the roots of <i>Myrica nana</i> Cheval., along with 11 known analogues (<b>7</b>–<b>17</b>). The structures were elucidated\nby spectroscopic analysis, as well as by calculated optical rotatory\ndispersion and derivatization reactions. Metabolites <b>1</b>–<b>3</b>, with a rare macrocyclic diarylhexane skeleton,\ndiffer from the familiar macrocyclic diarylheptanoids. The spasmolytic\nactivity of the isolated compounds was evaluated on acetylcholine-induced\ncontraction of isolated rat ileum. All isolated compounds exhibited\nsignificant spasmolytic activities with an EC<sub>50</sub> ranging\nfrom 1.4 to 5.1 μM. The spasmolytic mechanism of action of compound <b>1</b> could be related to the NO production, blockade of muscarinic\nreceptors, K<sup>+</sup> efflux, and cytosolic calcium reduction.