Two New Terpenoids From the Leaves and Twigs of Croton cnidophyllus and Their Anti‐Alzheimer's Disease Activities

ABSTRACT A new oleanane‐type triterpenoid, 3 β ‐acetyl‐15 α ‐hydroxy‐oleanane‐13 β ,28‐olide ( 1 ), and a new clerodane furanoditerpenoid, cnidophyllin A ( 2 ), together with 11 known compounds ( 3 – 13 ) were isolated and identified from the 95% ethanol extract of the leaves and twigs of Croton cnidophyllus . Except for compounds 3 and 7 , all other compounds were isolated for the first time from C. cnidophyllus . The structures of the new compounds were ascertained through a comprehensive application of spectroscopic techniques, including both one‐ and two‐dimensional nuclear magnetic resonance, infrared, and high‐resolution electrospray ionization mass spectrometry, while their absolute configurations were validated either through single‐crystal X‐ray diffraction analysis or via electronic circular dichroism calculations. Meanwhile, the single‐crystal X‐ray diffraction data of 8 has been reported for the first time. Additionally, the in vivo anti‐Alzheimer's disease (AD) activities of compounds 3–13 were assessed using the Caenorhabditis elegans AD pathology model. Among all the isolated compounds, compounds 4 and 7–13 significantly delayed the paralysis of the worms with AD‐like symptoms, which may be potential candidates for anti‐AD drugs.