Anti-Inflammatory Triterpenoids from the Stems of Microtropis Fokienensis

Three new ursane- and four new oleanane- type triterpenoids 1–7 were isolated, along with six known compounds 8–13, from the methanolic extract of Microtropis fokienensis. All structures were elucidated by mass and NMR spectroscopic methods. The isolates 4–10 and known compounds 14–17 that were previously isolated from this material were evaluated for anti-inflammatory activity based on effects against superoxide anion generation and elastase release by neutrophils in response to fMLP/CB. 11α,30-Dihydroxy-2,3-seco-olean-12-en-2,3-dioic anhydride (7) was the first triterpene anhydride from the genus of Microtropis to have the ring A expanded to a seven-membered ring; it showed significant anti-inflammatory activity against superoxide anion generation and elastase release. Unexpectedly, 30-hydroxy-2,3-seco-lup-20(29)-ene-2,3-dioic acid (17) showed the best effect against superoxide anion generation and elastase release with IC(50) values of 0.06 ± 0.01 and 1.03 ± 0.35 µg/mL, respectively. Compound 17 had a dioic acid function, and compound 7 had an anhydride function modification in ring A; both showed promising activity in the target assays.