Abstract:

To reveal suitable ecological zones and habitat characteristics about the growth of Potentilla glabra and to provide evidences for developing fully and protecting reasonably wild medical P. glabra resource we investigated and determined the major climatic factors that affect P. glabra production. P. glabra leaves collected from different sample plots were used for measuring the tannin, total flavonoids content and antioxidant activity. The response surface method was applied to optimize the extraction process of tannin and total flavonoids from P. glabra leaves with one-factor experimental design. The tannin content was determined with sodium tungstate-phosphomolybdic acid approach, the content of total flavonoids was determined with NaNO₂-Al(NO₃)₃ approach, and the antioxidant activity was determined with the DPPH· method. The relationship between variation in the parameters in six different sampling sites and the corresponding major climatic factors was analyzed with gray correlation degree analysis. The result showed that the quality of P. glabra was significantly different in terms of the parameters among the six different regions. Tannin content ranged from 4.95% to 7.74%, total flavonoids content ranged from 1.07% to 3.56%. P. glabra from Huzhu region had the highest tannins and flavonoids product, respectively 7.74% and 3.56%, while P. glabra in Helan mountains had the strongest antioxidant activity and the value of DPPH_IC50 was 6.9 μg·mL^-1; Grey correlation degrees analysis indicated that the annual extreme minimum temperature, frost free periods and the annual extreme maximum temperature were the main climatic factors affecting tannin content; Annual sunshine, the annual extreme minimum temperature and annual accumulated temperature were the major climatic factors influencing total flavonoids content, and annual sunshine, annual mean rainfall and the annual extreme minimum temperature were the major factors for regulating antioxidant activity.

Key words: Potentilla glabra, activity compounds, antioxidant activity, climatic factor, grey correlation degree