Daldiconoids A-G: 3,4-Secolanostane triterpenoids from the fruiting bodies of Daldinia concentrica and their anti-inflammatory activity

Seven undescribed 3,4-secolanostane triterpenoids, daldiconoids A-G (1–7), were isolated from the fruiting bodies of Daldinia concentrica. Daldiconoid A (1) was a highly modified 4,6,28,29-tetranorlanostane triterpenoid alkaloid featuring an unusual δ-lactam fused with a flanking cyclopentenone architecture. Their structures were determined by spectroscopic data, NMR calculations coupled with the DP4+ analysis, X-ray single-crystal diffraction, and chemical transformation. The plausible biosynthetic pathway for 1 was proposed. Compounds 1, 2, and 4–6 inhibited the expressions of IL-1β, IL-6, and TNF-α in lipopolysaccharide stimulated RAW264.7 cells at a concentration of 10 μM. Mechanistically, Compounds 1 and 2 blocked the JAK2/STAT3 signaling pathway induced by lipopolysaccharide.