RESUMO
Bioassay-guided fractionation led to the isolation of a series of triterpenoids (1-46) including 12 new ones (1-12) from the mushroom Inonotus obliquus. The structures of all the compounds were elucidated by spectroscopic analysis as well as by comparison with literature data. Triterpenoids 1-3, 6, 7, 16, 24, 25, 27, 38, 43, 44 and 46 showed strong α-glucosidase inhibition, with IC50 values from 11.5 to 81.8 µM. Their structure-activity relationships were discussed. Inonotusol F (24) showed the strongest inhibitory activity and it presented noncompetitive inhibition against α-glucosidase. Molecular docking and molecular dynamics stimulation further demonstrated that GLU302 and PHE298 were key amino acids for the inhibition of inonotusol F (24) towards α-glucosidase. This study indicates the vital role of triterpenoids in explaining hypoglycemic effect of Inonotus obliquus and provides important evidence for further development and utilization of this mushroom.
Assuntos
Agaricales/química , Inibidores de Glicosídeo Hidrolases/farmacologia , Hipoglicemiantes/farmacologia , Triterpenos/farmacologia , alfa-Glucosidases/metabolismo , Relação Dose-Resposta a Droga , Inibidores de Glicosídeo Hidrolases/química , Inibidores de Glicosídeo Hidrolases/isolamento & purificação , Humanos , Hipoglicemiantes/química , Hipoglicemiantes/isolamento & purificação , Cinética , Modelos Moleculares , Estrutura Molecular , Relação Estrutura-Atividade , Triterpenos/química , Triterpenos/isolamento & purificaçãoRESUMO
Ganoderma mushrooms are widely used in clinical therapies and functional foods. The antidiabetic effect of Ganoderma has become a research hot spot in recent decades. To search for a superior antidiabetic Ganoderma extract, five common Ganoderma species (G. lucidum, G. sinense, G. tsugae, G. applanatum, and G. leucocontextum) were investigated. A total of 10 fractions, including a total triterpenes fraction and a crude polysaccharides fraction for each, were prepared for further assays. Activities of α-glucosidase and α-amylase are inhibited dominantly by triterpenes from all five Ganoderma species rather than the polysaccharides. G. lucidum triterpenes inhibits α-glucosidase and α-amylase most significantly with IC50 values of 10.02 ± 0.95 µg/mL and 31.82 ± 4.30 µg/mL. Even more, triterpenes content was positively correlated with anti-α-glucosidase and anti-α-amylase activities. Therefore, triterpenes were considered to be the active compounds in inhibiting α-glucosidase and α-amylase activity. It is hoped that the results will provide more systematic information for the application of Ganoderma in the functional food and traditional medicine industries in the future.