Study on constituents of Scutellaria nepetifolia as a potent source of phytochemicals with NO inhibitory effect

Based on the long history of Scutellaria plants in east traditional medicines, several species of Scutellaria showed promising antioxidant, anti-inflammation and neuroprotection effects in pharmacological researches. Using bioassay-guided fractionation of various extract of Scutellaria nepetifolia, an endemic species that grows widely in Iran, based on on nitric oxide (NO) inhibitory activity against H2O2 induced NO production in PC12 pheochromocytoma cells led to the isolation of two iridoid compounds namely, as 6 beta-hydroxy 8-epiboshnaloside (1) and 1,5,9-epideoxy loganic acid (2) and Verbascoside (3). Finally, the interaction of isolated compounds with inducible nitric oxide synthase (iNOS) protein was simulated by molecular docking study. It is the first report of these two iridoid glycosides from Scutellaria spp. All three isolated compounds showed strong interaction with iNOS enzyme in molecular docking simulations. So, they possibly contributed in the NO inhibitory effect of S. nepetifolia.