Extraction and Isolation. Air-dried roots (2.0 kg) of P.
macropterum were ground and successively extracted at room
temperature with hexanes (3 × 12 L), EtOAc (3 × 5 L), and
MeOH (3 × 5 L). After the evaporation of solvents, the crude hexanes
(29 g), EtOAc (48 g), and MeOH (125 g) extracts were obtained. The
crude hexanes extract was separated by silica gel flash column
chromatography (FCC) and eluted with a gradient system of hexanes,