Two new labdane diterpenoids from the rhizomes of <i>Isodon yuennanensis</i>

<div><p>Two new labdane diterpenoids, <i>s</i>-trans-8(17),12<i>E</i>,14-labdatrien-20-oic acid (<b>1</b>), <i>s</i>-trans-12<i>E</i>,14-labdadien-20,8β-olide (<b>2</b>), along with 10 known compounds, hinokiol (<b>3</b>), ursonic acid (<b>4</b>), 2α,3α-dihydroxyolean-12-en-28-oic acid (<b>5</b>), 2α,3β,23-trihydroxyolean-12-en-28-oic acid (<b>6</b>), ethyl 3-(3,4-dihydroxyphenyl)lactate (<b>7</b>), ethyl rosmarinate (<b>8</b>), (<i>Z</i>,<i>E</i>)-2-(3,4-dihydroxyphenyl)ethenyl caffeic ester (<b>9</b>), tridecanoic acid (<b>10</b>), β-sitosterol (<b>11</b>) and daucosterol (<b>12</b>), were isolated from the 70% acetone extract of the rhizomes of <i>Isodon yuennanensis</i>. Their structures were elucidated based on the analyses of extensive spectroscopic data and physicochemical properties.</p>