Phytochemical study on the roots and rhizomes of Notopterygium incisum resulted in the isolation of six new coumarins, notoptetherins A - F (1-6), and 20 known analogues (7-26). Their structures were elucidated on the basis of extensive analyses of NMR and HRMS data, and the absolute configurations of 5 and 6 were established by Mo2(AcO)4-induced CD and exciton chirality, respectively. Moreover, a biomimetic synthesis of 6 from 21 was employed to confirm its absolute configuration. In a subsequent activity screening, compounds 12 and 17 exhibited potent inhibition against LPS-induced nitric oxide production in RAW 264.7 cells with IC50 values of 12.7 and 10.2 μM, respectively.
Keywords: Coumarins; Nitric oxide; Notopterygium incisum.
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