Isolation and structure elucidation of pyridine alkaloids from the aerial parts of the Mongolian medicinal plant Caryopteris mongolica Bunge.

The seven pyridine alkaloids 1-7, the flavonoid acacetin (8), and L-proline anhydride (9) have been isolated from the aerial parts of the Mongolian medicinal plant Caryopteris mongolica Bunge. The structures of the natural products 1-9 have been assigned by MS, as well as IR, 1D NMR (1H, 13C, DEPT), and 2D NMR (COSY, HSQC, HMBC, NOESY) spectroscopic methods. The compounds 2 and 4-7 represent new chemical structures. Acacetin (8) and L-proline anhydride (9) have been obtained from C. mongolica for the first time.