Anti-inflammatory isoflavones and isoflavanones from the roots of Pongamia pinnata (L.) Pierre.

A phytochemical study on the roots of Pongamia pinnata afforded five new isoflavone and isoflavanone derivatives (1-5), including two previously undescribed phenylisoflavones possessing an 1,2-oxetane ring, along with 21 known compounds (6-26) among which compound 18 is the first time to be isolated from nature. The structures of the isolated compounds were determined on the basis of 1D, 2D NMR, and HRESIMS. The absolute configurations of the compounds were assigned via analysis of the specific rotations and circular dichroism (CD) spectra, as well as by comparison of the calculated and experimental electronic circular dichroism (ECD) data. All the isolated compounds were evaluated for their inhibitory effects on NO production in LPS-stimulated BV-2 microglial cells. Twelve compounds exhibited different levels of inhibitory effects against NO production, and compound 1 showed the best activity with an IC50 value at 9.0 μM.