New monoterpenoid alkaloids from the aerial parts of <i>Uncaria hirsuta</i>

<div><p>To investigate the chemical constituents of medicinal plant <i>Uncaria hirsuta</i>, three new monoterpenoid alkaloids, named hirsutanines A–C (<b>1</b>–<b>3</b>), were isolated. Their structures with absolute configurations were elucidated by means of NMR, X-ray diffraction and CD analysis. Compound <b>3</b> was the first dimeric monoterpenoid alkaloid obtained from genus <i>Uncaria.</i></p></div>