Guanidine alkaloids from Plumbago zeylanica.

Eleven new guanidine alkaloids, plumbagines A-G (2-8) and plumbagosides A-D (9-12), as well as two known analogues (1, 13), were isolated from the aerial parts of Plumbago zeylanica. Their structures were elucidated by spectroscopic analyses including 1D and 2D NMR, MS, IR, and CD methods. The absolute configuration of 1 was determined by single-crystal X-ray diffraction of its derivative (1a).