Benzophenone and Benzoylphloroglucinol Derivatives from Hypericum sampsonii with Anti-Inflammatory Mechanism of Otogirinin A

Three new compounds, 4-geranyloxy-2-hydroxy-6-isoprenyloxybenzophenone (1), hypericumone A (2) and hypericumone B (3), were obtained from the aerial parts of Hypericum sampsonii, along with six known compounds (4-9). The structures of these compounds were determined through spectroscopic and MS analyses. Hypericumone A (2), sampsonione J (8) and otogirinin A (9) exhibited potent inhibition (IC50 values <= 40.32 mu M) against lipopolysaccharide (LPS)-induced nitric oxide (NO) generation. Otogirinin A (9) possessed the highest inhibitory effect on NO production with IC50 value of 32.87 +/- 1.60 mu M. The well-known proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha) was also inhibited by otogirinin A (9). Western blot results demonstrated that otogirinin A (9) downregulated the high expression of inducible nitric oxide synthase (iNOS). Further investigations on the mechanism showed that otogirinin A (9) blocked the phosphorylation of MAPK/JNK and I kappa B alpha, whereas it showed no effect on the phosphorylation of MAPKs/ERK and p38. In addition, otogirinin A (9) stimulated anti-inflammatory M2 phenotype by elevating the expression of arginase 1 and Kruppel-like factor 4 (KLF4). The above results suggested that otogirinin A (9) could be considered as potential compound for further development of NO production-targeted anti-inflammatory agent.