Isolation and anti‐inflammatory evaluation of diterpene lactones from Andrographis paniculata collected in Bac Giang province, Vietnam

Phytochemical components of the aerial parts of Andrographis paniculata collected in Bac Giang province was investigated. Fourteen compounds, including seven labdane diterpene lactones [andrographolide (1), 3,19‐isopropylidene‐andrographolide (2), andropanolide (4), 14‐deoxy‐12‐hydroxyandrographolide (5), 14‐dehydroxyandrographolide‐12‐sulfonic acid (6), 14‐deoxy‐11,12‐didehydroandrographolide (8), 14‐deoxy‐14,15‐didehydroandrographolide (11)], together with four diterpene glycosides [andrographiside (3), neoandrographolide (7), andropanoside (9), 14‐deoxy‐11,12‐didehydroandrographiside (10)], and three iridoid glycosides [harpagide (12), 6‐epi‐8‐O‐acetyl‐harpagide (13), procumbide (14)] were isolated. Among these, 14‐dehydroxyandrographolide‐12‐sulfonic acid (6) was isolated for the first time from natural resource, and for the first‐time harpagide (12) was isolated from Andrographis paniculata species. The detailed structures of isolated compounds were elucidated by analyses of 1D and 2D NMR spectra and compared to the published data. Diterpene lactones, 1–2, 5 and 10–11, were evaluated for their anti‐inflammatory inhibition on LPS‐triggered inflammatory responses in RAW 264.7 cells, in which 1 and 2 showed significantly potent inhibition on NO production with IC50 values of 1.3 and 0.34 µm, respectively.