Anti-inflammatory activity of ingredients from the heartwood of Vietnamese Dalbergia oliveri Gamble ex Prain

Objectives: To investigate the phytochemical constituents of Vietnamese Dalbergia oliveri and their inhibition of NO production. Methods: The ethyl acetate soluble fraction was subjected to column chromatography using silica gel and Sephadex LH-20 to isolate compounds. The chemical structures of isolated compounds were identified by nuclear magnetic resonance data and comparison with previously reported literature. The anti-inflammation effects of the isolated compounds on the lipopolysaccharide (LPS)-induced NO production in RAW 264.7 cells were measured using the Griess reaction. Results: Nine secondary metabolites (1−9) were isolated successfully from the heartwood of D. oliveri. The chemical structures of these compounds were identified as daidzein (1), formononetin (2), 3,7-dihydroxy-4′-methoxyflavone (3), liquiritigenin (4), 3′-methoxydaidzein (5), dalbergin (6), butin (7), sativanone (8), and isoliquiritigenin (9). This is the first time that compounds 1, 3, 5−8 have been isolated from D. oliveri. In the NO production inhibition, compounds 7 and 9 exhibited the most potent inhibitory activity, with IC50 values of 7.6 and 11.2 μM, respectively, followed by 3−6, with IC50 values from 19.6 to 28.7 μM. Conclusion: The results suggested that D. oliveri and its natural products might exert anti-inflammatory effects due to their NO-inhibiting actions.