New alkaloids from Daphniphyllum himalense

Abstract

Nine new Daphniphyllum alkaloids (1–9) and 16 biosynthetically related known ones were obtained during the phytochemical investigation into a Nepalese plant, Daphniphyllum himalense. Structures were assigned to these compounds based on careful spectroscopic interpretation and NMR comparison with literature data. Deuteration of H₂-16 in CD₃OD due to quick keto-enol tautomerization was observed for both 2 and 3. The recently reported 3β-hydroxydaphniyunnine A was re-examined and its structure was revised to be 21-deoxymacropodumine D via X-ray diffraction analysis. All the isolates were screened preliminarily for their in vitro inhibitory effects against four kinases, PTP1B, aurora A, HDAC6 and IKK-β, and selective alkaloids exhibited weak activities at 20 μg mL⁻¹.