New Octadecanoid Enantiomers from the Whole Plants of Plantago depressa

Abstract

In this study, 19 octadecanoid derivatives-four pairs of enantiomers (<b>1</b>⁻<b>8</b>), two racemic/scalemic mixtures (<b>9</b>⁻<b>10</b>), and nine biosynthetically related analogues-were obtained from the ethanolic extract of a Chinese medicinal plant, <i>Plantago depressa</i> Willd. Their structures were elucidated on the basis of detailed spectroscopic analyses, with the absolute configurations of the new compounds assigned by time-dependent density functional theory (TD-DFT)-based electronic circular dichroism (ECD) calculations. Six of them (<b>1</b>, <b>3</b>⁻<b>6,</b> and <b>9</b>) were reported for the first time, while <b>2</b>, <b>7,</b> and <b>8</b> have been previously described as derivatives and are currently obtained as natural products. Our bioassays have established that selective compounds show in vitro anti-inflammatory activity by inhibiting lipopolysaccharide-induced nitric oxide (NO) production in mouse macrophage RAW 264.7 cells.