A new pentacyclic triterpenoid from the leaves of <i>Rhododendron dauricum</i> L. with inhibition of NO production in LPS-induced RAW 264.7 cells

Abstract

A new pentacyclic triterpenoid, 3-oxo-urs-11,13(18)-dien-28-oic acid (<b>1</b>), along with twelve known triterpenoids, <i>α</i>-amyrin (<b>2</b>), 19<i>α</i>-hydroxy-<i>α</i>-amyrin (<b>3</b>), triptohypol E (<b>4</b>), uvaol (<b>5</b>), 2<i>α</i>,3<i>α</i>-dihydroxyurs-11-en-13<i>β</i>,28-olide (<b>6</b>), 3<i>β</i>-hydroxyurs-11-en-13<i>β</i>,28-olide (<b>7</b>), ursolic acid (<b>8</b>), asiatic acid (<b>9</b>), oleanolic acid (<b>10</b>), aegiceradienol (<b>11</b>), obtusalin (<b>12</b>) and betulinic acid (<b>13</b>) were isolated from the leaves of <i>Rhododendron dauricum</i> L. Their structures were established from spectroscopic data and comparison with reported values. Among them, compounds <b>3</b>, <b>4</b>, <b>6</b>, <b>7</b> and <b>11</b> were isolated from the Ericaceae family for the first time. Compounds <b>2</b>, <b>5</b>, <b>9</b>, <b>12</b> and <b>13</b> were obtained from <i>R. dauricum</i> for the first time. Additionally, compounds <b>6</b>, <b>10</b> and <b>11</b> significantly inhibited the levels of NO in LPS-stimulated RAW 264.7 cells at 3 μM.