New alkaloids from the twigs and leaves of <i>tabernaemontana divaricata</i> and their neuroprotective effects

Two novel monoterpenoid quinoline alkaloids, tabernacatines A and B (<b>1</b> and <b>2</b>), and a new monoterpenoid indole alkaloid, tabernacatine C (<b>3</b>), along with three known alkaloids (<b>4 </b>-<b> 6</b>), were isolated from the twigs and leaves of <i>Tabernaemontana divaricata</i>. Their structures were elucidated based on UV, IR, HR-ESI-MS, NMR spectra analysis, X-ray diffraction, and ECD calculation methods. Compounds <b>1 - 6</b> were evaluated for their neuroprotective effects in glutamate-induced HT22 cells, and compounds <b>4</b>-<b>6</b> exhibited potent neuroprotective effects.