[Studies on dynamic change of total ginkgolic acids in Ginkgo biloba leaves of different aged trees and different collecting seasons].

To study dynamic change of total ginkgolic acids in Ginkgo biloba leaves of the different aged trees and different collecting seasons. The content of total ginkgolic acids in G. biloba leaves was determined by HPLC. A Alltima C18 (4.6 mm x 250 mm, 5 microm) and the mobile phase of methanol and 1% acetic acid (90:10) were used, the flow rate was 1.0 mL x min(-1), and the wavelength was 310 nm. The content were calculated with external standard method. The content of total ginkgolic acids in G. biloba leaves was in the range of 0.48% to 2.51% in different collecting seasons. The content reached maximum at the end of May and the beginning of June, and then declined gradually. In different aged trees, the content in the older ages was lower than that in the younger ages. The results provide scientific basis for the collecting season of G. biloba leaves.