Norsecurinamines A and B, two norsecurinine-derived alkaloid dimers from the fruits of Flueggea virosa

The phytochemical investigation on the fruits of Flueggea virosa resulted in the discovery of two new norsecurinine-derived alkaloid dimers, norsecurinamines A and B (1 and 2). Compound 1 is the first hetero-dimeric alkaloid possessing norsecurinine and donaxaridine units, and 2 represents the first example of NH-linked dimeric Securinega alkaloid. Their structures and absolute configuration were elucidated on the basis of extensive spectroscopic analysis as well as single-crystal X-ray diffraction method. A plausible biogenetic pathway of 1 was also proposed.