Semisynthesis of 22,25-Epoxylanostane Triterpenoids: Structure Revision and Protective Effects against Oxygen-Glucose Deprivation/Reoxygenation Injury in H9c2 Cells

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.

Thiolactones and Δ8,9-Pregnene Steroids from the Marine-Derived Fungus Meira sp. 1210CH-42 and Their α-Glucosidase Inhibitory Activity

The fungal genus Meira was first reported in 2003 and has mostly been found on land. This is the first report of second metabolites from the marine-derived yeast-like fungus Meira sp. One new thiolactone (1), along with one revised thiolactone (2), two new Δ^8,9-steroids (4, 5), and one known Δ^8,9-steroid (3), were isolated from the Meira sp. 1210CH-42. Their structures were elucidated based on the comprehensive spectroscopic data analysis of 1D, 2D NMR, HR-ESIMS, ECD calculations, and the pyridine-induced deshielding effect. The structure of 5 was confirmed by oxidation of 4 to semisynthetic 5. In the α-glucosidase inhibition assay, compounds 2-4 showed potent in vitro inhibitory activity with IC₅₀ values of 148.4, 279.7, and 86.0 μM, respectively. Compounds 2-4 exhibited superior activity as compared to acarbose (IC₅₀ = 418.9 μM).