Alstolarsines A–E, Indoline Alkaloids with Two Different Carbon Skeletons from Alstonia scholaris

Five complex indoline alkaloids, alstolarsines A–E (1–5) possessing two unprecedented carbon skeletons of 6/5/5/7/6/6(5) fused polycyclic systems, were isolated from Alstonia scholaris. Their structures were characterized using various methods including spectroscopic data, ECD spectra, and single-crystal X-ray diffraction. The inhibitory activities of alstolarsines A–D (1–4) on DRAK2 phosphorylation and ATP-citrate lyase were evaluated, but all of them were inactive.