Lignans and clerodane diterpenoids from Tinospora sinensis .

Sixteen lignans with diverse carbon skeletons, including tetrahydrofuran lignans (1, 13-18), 7,9'-dinorlignan (2), dibenzylbutane lignans (9-10), aryl tetrahydronaphthalene lignans (11-12), dihydrobenzofuran neolignans (19-20), 8- O -4' neolignans (21-22), and six clerodane diterpenoid glucosides (3-8) were isolated from the 70% ethanolic extract of the stems of Tinospora sinensis (Lour.) Merr. Their structures were established by spectroscopic analyses and chemical methods. Among all these isolates, compounds 1-2 and 3-4 were determined as previously undescribed lignans and clerodane diterpenoids respectively, and compounds 9-13 and 17-22 were discovered from T. sinensis for the first time. In addition, it was the first time to report three types of lignans including 7,9'-dinorlignan, dihydrobenzofuran neolignan and 8- O -4' neolignan from T. sinensis . The biological activities of all isolated compounds were assessed in terms of their nitric oxide production inhibitory activity in LPS stimulated RAW264.7 cells. The results showed that compound 20 exhibited a mild NO production inhibitory effect with an IC 50 value of 17.43 ± 2.06 μM.