Several chromones from the stems of Polygonum aubertii Henry

Two new 2-alkylchromanones, 2-tricosyl-2,5,7-trihydroxy-chromanone (6) and 2-pentacosyl-2,5,7-trihydroxy-chromanone (7), together with five known 2-alkylated chromones and chromanones (1-5), were isolated from the stems of Polygonum aubertii Henry. The structures of these compounds were established by spectroscopic methods including extensive 1D, 2D NMR ((1)H-(1)H COSY, HSQC, and HMBC), and HR-ESI-MS techniques. In addition, a plausible biosynthetic pathway for these compounds is described.