Triangesinenolides A–C: Trimeric Phthalides with Anti-Renal Fibrosis Potential from <i>Angelica sinensis</i>

Trimeric phthalides in nature are rarely reported. This research successfully isolated three novel trimeric phthalides, triangesinenolides A-C (<b>1</b>-<b>3</b>), from <i>Angelica sinensis</i>. These compounds, derived from <i>Z</i>-ligustilide via diverse linkage patterns, display intricate polycyclic skeletons. Their structures were confirmed by spectroscopic and crystallographic analyses. Unlike previously identified trimeric phthalides, triangesinenolide C (<b>3</b>) is the first trimeric phthalide synthesized via [2 + 2]/[4 + 2] cycloaddition. <i>In vitro</i> assays evaluated the anti-renal fibrosis activity of trimeric phthalides for the first time.