Anti-inflammatory Activity of Tanshinone-Related Diterpenes from Perovskia artemisioides Roots.

Perovskia artemisioides is a perennial and aromatic plant widely distributed in the Baluchestan region of Iran. Phytochemical analysis of a n -hexane extract of P. artemisioides roots, guided by an analytical approach based on LC-ESI/LTQOrbitrap/MS/MS, yielded six previously undescribed diterpenoid compounds ( 2 , 9 - 11 , 16 , and 20 ), and 19 known diterpenoids, for which the structures were elucidated by 1D and 2D NMR experiments. Some of the isolated compounds showed significant anti-inflammatory activity using J774A.1 macrophage cells stimulated with Escherichia coli lipopolysaccharide. In particular, compounds 6 , 8 , 17 , 18 , 20 , and 22 significantly inhibited the release of nitric oxide and the expression of related pro-inflammatory enzymes, such as inducible nitric oxide synthase and cycloxygenase-2. Moreover, two compounds that showed the highest activity in reducing nitric oxide release ( 6 and 18 ) were tested to evaluate their effects on nitrotyrosine formation and reactive oxygen species release. Both compounds inhibited ROS release and, in particular, compound 6 also inhibited nitrotyrosine formation at all tested concentrations, thus indicating a significant antioxidant potential.