Prenylated Polyphenols from Broussonetia kazinoki as Inhibitors of Nitric Oxide Production

Excessive nitric oxide (NO) production by macrophages has been involved in inflammatory diseases. Seven polyphenols ( - ) were isolated from and investigated as potential inhibitors of NO overproduction in lipopolysaccharide (LPS)-activated RAW 264.7 cells. Among them, four prenylated polyphenols ( - and ) with a catechol moiety efficiently suppressed the LPS-induced high level of NO with IC values of less than 6 µM. The compounds - and also attenuated protein and mRNA levels of inducible nitric oxide synthase (iNOS). Moreover, they suppressed the nuclear factor κB (NF-κB) activity by inhibiting the degradation of inhibitory-κB-α (I-κB-α) and the translocation of NF-κB into the nucleus in LPS-activated macrophages. Taken together, these findings suggest that polyphenols from might be beneficial for treatment of inflammatory diseases.