Isatisindigoticanine A, a novel indole alkaloid with an unpresented carbon skeleton from the roots of Isatis tinctoria

Abstract

Isatisindigoticanine A (1), a new indole alkaloid with an unusual carbon skeleton of a benzofuran-3-one unit connected with a 1H-indole-3-yl unit and a 4-(1,2-dihydroxyethyl)-6-oxa-3-azabicyclo[3.1.0]hexan-2-one unit via a C-3－C-8'' bond and a C-4'－C-8'' bond, was obtained from the roots of Isatis tinctoria. Its structure was determined by physicochemical properties and spectroscopic methods including 1 D, 2 D NMR, IR, HRESIMS data. The absolutely configurations were deduced by comparison of its experimental CD and calculated ECD spectra. Nitric oxide (NO) inhibitory activities of isatisindigoticanine A was also evaluated in the LPS-stimulated RAW 264.7 cells, however, no inhibitory effect was presented.

Keywords: Anti-inflammatory activity; Isatis tinctoria; indole alkaloid; isatisindigoticanine A.