(±)-odoriferols A-E, five pairs of enantiomeric flavonoids and benzofurans from Dalbergia odorifera with anti-inflammatory activity.

Twelve previously unreported compounds, including five pairs of enantiomeric benzofuran and flavonoid derivatives (1-5), along with one benzofuran (6) and one triterpenoid (7), were isolated from the heartwood of Dalbergia odorifera (Fabaceae). Their structures and absolute configurations were elucidated by comprehensive spectroscopic analysis (UV, IR, ESI-MS, NMR) combined with ACD/Structure Elucidator, NMR and ECD calculations. Structurally, compound 1 featured a unique spiro[4,4] skeleton. Compound 2 possessed a rare 6/5/5 tricyclic system containing a 1-methyl-2,7-dioxabicyclo[3.2.1]octan-6-one moiety. Plausible biosynthetic pathways of compounds 1 and 2 were proposed. Seven compounds (1a, 2a, 2b, 4a, 4b, 6 and 7) significantly inhibited NO production in LPS-induced RAW264.7 cells, with IC50 values ranging from 6.3 to 19.9 μM. Notably, compound 7 exhibited the best inhibitory activity with an IC50 value of 6.3 μM.