C-methylated homoisoflavanones from the rhizomes of polygonatum cyrtonema and their chemotaxonomic significance

A phytochemical investigation of the rhizomes of Polygonatum cyrtonema, a traditional Chinese medicine and healthy food named "Huang-jing" (Polygonati Rhizoma), led to the isolation of 22 phenolic derivatives including an undescribed (1) and nine (2–10) known C-methylated homoisoflavanones, two common homoisoflavanones (11, 12), four flavanones (13–16), one chalcone (17), and five octopamine derivatives (18–22). The structure of compound 1 was established mainly by spectroscopic methods, including 1D-/2D-NMR and electronic circular dichroism (ECD). The known compounds were identified by comparing the observed and reported physicochemical properties and spectroscopic data published in the literature. Polygonatone H (8) and 5,7,2′-trihydroxy-4′-methoxy-6,8-dimethyl-homoisoflavanone (9) exhibited significant cytotoxic effects against four human cancer cell lines (HCT-116, AGS, U-87 MG, and PC-12) with IC50 values ranging from 2.2 to 9.8 μM. Furthermore, the chemotaxonomic significance of the isolated C-methylated homoisoflavanones was briefly discussed.