Nobiletin, a citrus
flavonoid has been associated with various beneficial biological activities.
4'-Demethylnobiletin (4DN) is a major metabolite of
nobiletin and its tissue level was found to be much higher than that of
nobiletin after
oral administration of
nobiletin in mice. Anti-inflammatory effects of 4DN were studied in
lipopolysaccharide (LPS)-treated RAW 264.7 macrophages. The results showed 4DN not only dose-dependently inhibited LPS-induced
nitric oxide production, but also significantly reduced expression of pro-inflammatory mediators, namely
PGE2, IL-1β and
IL-6. 4DN potently suppressed the expression of iNOS and COX-2 at both
protein and
mRNA levels. 4DN also inhibited nuclear translocation of NF-κB and
AP-1. Furthermore, we demonstrated that 4DN activated
transcription factor Nrf2 and its dependent genes including HO-1 and NQO1 whose expression may contribute to anti-inflammatory effects. The results demonstrated anti-inflammatory effects of 4DN and provided a scientific basis for using
nobiletin as a nutraceutical to inhibit
inflammation-driven diseases.