Four indole alkaloids,
alstonlarsines A–D (1–4),
were isolated from Alstonia
scholaris and structurally characterized. Compound 1 possesses a new carbon skeleton with a cage-shaped 9-azatricyclo[4.3.1.03,8]decane motif, and compounds 2–4 feature a rare carbon skeleton that was found in nature
for the first time. Plausible biosynthetic routes for 1–4 are proposed. Compound 1 showed
DRAK2 inhibitory activity with an IC50 value of 11.65 ±
0.63 μΜ.