Two Novel and Anti‐Inflammatory Constituents of Artocarpus rigida

With the scope of our search for biologically active compounds, two new phenolic compounds, artocarpols G ( 1 ) and H ( 2 ), and two known compounds, rubraflavone C ( 3 ) and trans‐stilbene‐2,4,3′,5′‐tetrol, were isolated from the root bark of Artocarpus rigida. Their structures were determined by spectroscopic methods and comparison with data reported in the literature. Compound 4 , previously isolated from this plant, strongly inhibited in a concentration‐dependent manner the release of β‐glucuronidase and histamine from mast cell degranulation caused by compound 48/80, with IC₅₀ values of 10.9±1.4 and 13.2±0.6 μM , respectively. Compound 4 also showed a concentration‐dependent inhibitory effect on the formyl‐peptide‐stimulated superoxide anion formation in neutrophils with an IC₅₀ value of 26.0±5.6 μM .