Oxomollugin, a potential inhibitor of lipopolysaccharide-induced nitric oxide production including nuclear factor kappa B signals.

Mollugin, a naphthoquinone derivative, was reported to possess various biological activities such as anti-inflammatory and anti-tumor activity. Mollugin isolated from Rubia tinctorum roots inhibited lipopolysaccharide-induced nitric oxide (NO) production in RAW264.7 macrophages. However, mollugin synthesized for further investigation of its anti-inflammatory mechanism showed weak activity in addition to unstable assay results. From the result of analysis on a degradation product of mollugin, oxomollugin was found to be the main active substance of mollugin degradation, showing a potent inhibitory activity on NO-production including nuclear factor kappa B signals.