Clerodane Furanoditerpenoids from Tinospora bakis (A.Rich.) Miers (Menispermaceae)

Tinospora bakis (A.Rich.) Miers (Menispermaceae) has traditionally been used to alleviate headaches, rheumatism, mycetoma, and diabetes, among others. Despite its extensive use, the active components of the plant have never been investigated. In this work, a series of furanoditerpenoids (1-18) and five compounds from other classes (19-23) were isolated from T. bakis. Notably, two new compounds were discovered and named: tinobakisin (1) and tinobakiside (10). Their molecular structures were elucidated with NMR, MS, UV, IR, and ECD spectra. Additionally, known compounds (2-9 and 11-23) were corroboratively identified through spectral comparisons with previously reported data, while highlighting and addressing some inaccuracies in the prior literature. Remarkably, compounds 6, 7, 13, and 17 exhibited a superior anti-glycation effect, outperforming established agents like rutin and quercetin in a lab model of protein glycation with glucose. The overall findings suggest that furanoditerpenoids play a crucial role in the antidiabetic properties of T. bakis. This research marks the first comprehensive phytochemical investigation of T. bakis, opening the door for further investigation into furanoditerpenoids and their biological mechanisms.