Alkaloid constituents from the fruits of Flueggea virosa

Three new indole alkaloids, flueindolines A–C ( 1 – 3 ), along with nine known alkaloids ( 4 – 12 ), were isolated from the fruits of Flueggea virosa (Roxb. ex Willd.) Voigt. Compounds 1 and 2 are two new fused tricyclic indole alkaloids possessing an unusual pyrido1, 2-aindole framework, and 3 presents a rare spiro (pyrrolizidinyl-oxindole) backbone. Their structures with absolute configurations were elucidated by means of comprehensive spectroscopic analysis, chemical calculation, as well as X-ray crystallography. Chiral resolution and absolute configuration determination of the known compounds 4 , 10 , and 11 were reported for the first time. The hypothetical biogenetical pathways of 1 – 3 were herein also proposed.