Abstract:

Objective: To optimize the extraction of polyphenol from Panax notoginseng flowers and examine its antioxidant
activity. Methods: Ethanol concentration, and extraction temperature and time were identified as main variables influencing
the extraction yield of polyphenols. The levels of the three variables were optimized by response surface methodology with
central composite design. As a result, a polynomial regression and response surface plots were established indicating the
effects of the studied variables on extraction efficiency. Moreover, the correlation between polyphenol concentration from
Panax notoginseng flowers and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging ability was examined. Results:
The optimal conditions for polyphenol extraction were determined as follows: extraction temperature, 75 ℃; extraction
time, 47 min; and ethanol concentration, 48%. Under these conditions, the actual extraction rate of polyphenols was
58.95 mg/g, representing 98.44% of the predicted value. The correlation coefficient between DPPH radical scavenging ability
and polyphenol yield was 0.757 208. Conclusion: Under the optimal conditions, the good agreement between predicted and
observed extraction rates of polyphenols suggests the reliability of the predicted results. The strong correlation between
DPPH radical scavenging ability and polyphenol yield demonstrates potent antioxidant activity of polyphenols from Panax
notoginseng flowers.

Key words: Panax notoginseng flowers, polyphenol, response surface methodology, extraction, antioxidant