C-Methylated flavanones from the rhizomes of Matteuccia intermedia and their α-glucosidase inhibitory activity.

One new flavanonol, demethylmatteucinol (1), and nine new flavanone glucoside derivatives, matteflavosides H-J (2-4) and matteuinterates A-F (5-10), were isolated from the rhizomes of Matteuccia intermedia C.Chr., along with 21 known flavanones (11-31). Notably, all of them contain C-methylation in the A-ring. The structures of the compounds were elucidated by spectroscopic methods and chemical derivatization. The α-glycosidase inhibition assay indicated that compounds 12-17 showed potent inhibitory activity with IC₅₀ values of 12.4-69.7 μM, which suggested their hypoglycemic effect.