Bistinospinosides A and B, Dimeric Clerodane Diterpene Glycosides from Tinospora sagittata

Two dimeric clerodane diterpene glycosides, namely, bistinospinosides A (1) and B (2), were isolated from the roots of Tinospora sagittata. Their structures were elucidated by extensive spectroscopic data interpretation. The compounds feature an unusual 1,4-epoxycyclohexane ring in their structures and may be biosynthetically constructed via an intermolecular Diels-Alder [4+2] cycloaddition from the corresponding clerodane diterpene. The compounds were evaluated in a nitric oxide inhibitory assay using J774.1 macrophage-like cells.