Inhibition of nuclear factor-kappaB activation by 2',8''-biapigenin.

Inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) play a key role in the inflammatory processes. Improper overproduction of NO and prostaglandins by both enzymes are also believed to be involved in the pathogenesis of certain human cancers. Crude extracts of Selaginella tamariscina are used as an oriental medicine, which has been reported to inhibit the production of proinflammatory cytokines and cause cell cycle arrest. We isolated 2',8''-biapigenin from S. tamariscina and investigated whether it modulates iNOS and COX-2 expressions in Raw264.7 macrophages stimulated with lipopolysaccharide (LPS). We found that 2',8''-biapigenin blocked the transactivations of iNOS and COX-2 genes via the inactivation of nuclear factor-kappaB by preventing the nuclear translocation of p65. Hence, it may be possible to develop S. tamariscina extracts or 2',8''-biapigenin as a useful agent for cancer chemoprevention or for the treatment of inflammatory diseases.