Three rare anti-inflammatory sesquiterpene lactones from Magnolia grandiflora

Four new sesquiterpene lactones(SLs)(1–4),along with a biosynthetically related SL(5),have been isolated from the leaves of Magnolia grandiflora.Magrandate A(1)is notable as the first C18 homogemarane type SL,featuring a unique 1,7-dioxaspiro[4.4]nonan-6-one core.Compounds 2 and 3,representing the first instances of chlorine-substituted gemarane-type SL analogs in natural products,were also identified.The structures of these isolates were elucidated through a combination of spectroscopic data analysis,electronic circular dichroism calculations,and X-ray single-crystal diffraction analysis.All isolates demonstrated anti-inflammatory activity in lipopolysaccharide-stimulated RAW264.7 cells.Notably,3–5 showed a significant inhibitory effect on nitric oxide production,with IC50 values ranging from 0.79 to 4.73μmol·L^(−1).Additionally,4 and 5 exhibited moderate cytotoxic activities against three cancer cell lines,with IC50 values between 3.09 and 11.23μmol·L^(−1).

Bioassay-guided isolation of α-Glucosidase inhibitory constituents from Hypericum sampsonii

This study employed the α-glucosidase inhibitory activity model as an anti-diabetic assay and implemented a bioactivity-guided isolation strategy to identify novel natural compounds with potential therapeutic properties.Hypericum sampsonii was investigated,leading to the isolation of two highly modified seco-polycyclic polyprenylated acylphloroglucinols(PPAPs)(1 and 2),eight phenolic derivatives(3-10),and four terpene derivatives(11-14).The structures of compounds 1 and 2,featuring an unprecedented octahydro-2H-chromen-2-one ring system,were fully characterized using extensive spectroscopic data and quantum chemistry calculations.Six compounds(1,5-7,9,and 14)exhibited potential inhibitory effects against α-glucosidase,with IC_(50) values ranging from 0.050±0.0016 to 366.70±11.08μg·mL^(-1).Notably,compound 5(0.050±0.0016μg·mL^(-1))was identified as the most potential α-glucosidase inhibitor,with an inhibitory effect about 6900 times stronger than the positive control,acarbose(IC_(50)=346.63±15.65μg·mL^(-1)).A docking study was conducted to predict molecular interactions between two compounds(1 and 5)and α-glucosidase,and the hypothetical biosynthetic pathways of the two unprecedented seco-PPAPs were proposed.