The capitula from cultivated plants of H. annuus L. was collected during August 2011 from the farm located at 1488 m above sea levelat 37◦0132N latitude and 103◦0628E longitude in the mid-hillsof Jingtai, Gansu, China. Harvested capitula were shade dried.
Ray florets and disc florets from the dried capitula were separated manually, then pulverized in the blender and sieved through a 60-mesh screen resulting in ray floret powder and disc floret powder, respectively. The sample powders were stored at room temperature in a brown desiccator with oxygen scavenger.