Two new diterpenoids from Leonurus japonicus

Abstract Two new labdane-type diterpenoids, 5-ethoxy-3-(2-((R)-4-hydroxy-2,5,5,8a-tetramethyl-3-oxo-3,5,6,7,8,8a-hexahydronaphthalen-1-yl)ethyl)furan-2(5H)-one (1), and 5-hydroxy-4-(2-((1R,3S,7aS)-1-hydroxy-4,4,7a-trimethyl-3-propionyloctahydroisobenzofuran-1-yl)ethyl)furan-2(5H)-one (2), were isolated from the EtOH extract of the herb of Leonurus japonicus Houtt., Lamiaceae. Their chemical structures were determined by analysis of 1D, 2D NMR, HRESIMS, and by comparison with known analogs.