Objective: To find out the seasonal variation of active alkaloids in Zhebeimu(F. thunbergii) collected from Zhejiang Ninbo and Jiangsu Nantong, and confirm the suitable harvesting time for the crude drug.
Method: Determining the alkaloid contents in the samples of Zebeimu collected monthly from the above-said twoplaces by improved colormetric method.
Result: The alkaloid accumulation patterns of the samples from two places are very similar, with the highest contents appearing in samples collected in January of February, and the absolute amounts in samples harvested in May.
Conclusion: The optimum time for harvesting Zhebeimu is in May.