Figure 1.

Major component with platelet aggregation-inhibiting activity in H. sylvestris. Using activity-guided analysis, crude extract from the heads (500 mg) was divided into five fractions by G-50 gel filtration column according to 280 and 215 nm absorption. G-50 gel (B) and bioassay data (A) were obtained simultaneously. Fraction III (gray shadow) accounted for 60% of inhibited platelet aggregation. Fraction III was collected and further analyzed by C₁₈ reverse-phase (RP) column. Substance absorption was monitored at 215 nm. Samples were gathered every minute, and bioactivity was tested immediately. Results showed that PGE1 was the only active compound (gray shadow) (C,D).