Diterpenoids and Their Glycosides From the Stems of Tinospora crispa With Beta-Cell Protective Activity

Seven previously undescribed diterpenoids, tinocrisposides A–D (1–4) and borapetic acids A (5), B (6), and C (7), together with 16 known compounds, were isolated from the stem of Tinospora crispa (Menispermaceae). The structures of the new isolates were elucidated by spectroscopic and chemical methods. The β-cell protective effect of the tested compounds was examined on insulin-secreting BRIN-BD11 cells under dexamethasone treatment.