Cytotoxic iridoid glycosides from the aerial parts of <i>Paederia yunnanensis</i>

Three previously undescribed iridoid glycosides, 6<i>α-O</i>-<i>trans</i>-sinapoyl-paederosidic acid ethyl ester (<b>1</b>), 6'-<i>O</i>-<i>trans</i>-feruloyl-paederosidic acid methyl ester (<b>2</b>), and 10-<i>O</i>-<i>trans</i>-<i>p</i>-coumaroyl-(4<i>S</i>,6<i>R</i>)-3,4-dihydro-3<i>β</i>-ethoxypaederoside (<b>3</b>), were isolated from the 90% EtOH extract of the aerial parts of <i>Paederia yunnanensis</i>. The structures of the new compounds were elucidated by spectral methods such as 1D and 2D (¹H-¹H COSY, HMQC, and HMBC) NMR spectrometry, HR-ESI-MS, as well as ECD data. The isolated compounds were tested <i>in vitro</i> for cytotoxic activity against five tumor cell lines. These results revealed that <b>3</b> exhibited some cytotoxicities against all the tested tumor cell lines with IC₅₀ value less than 20.0 μM and provided a scientific basis for further processing and utilization of <i>P. yunnanensis</i>.