Abstract:

Using phlorizin as reference substance, Folin-Ciocalteu colorimetric assay for polyphenols extracted from
Docynia Dcne. was systematically investigated for developing an optimal colorimetric method. The contents of polyphenols
in three species of Docynia Dcne. were determined and compared as well as in different parts of Docynia longiunguis.
The optimum colorimetric conditions were determined as follows: 0.5 mL of FC reagent and 2.5 mL of 10% Na2CO3,
7 min of reaction time, and 55 ℃ of reaction temperature. The absorbance of phlorizin was in good linear relationship with
concentration in the range of 1.252–15.024 μg/mL, R2 = 0.999 1, and the average recovery for the analysis of spiked samples
was 100.08%, with RSD of 2.43%. The contents of polyphenols in leaves of three species were significantly different,
with the lowest and highest levels detected in Docynia delavayi (12.55 g/100 g) and Docynia longiunguis (25.35 g/100 g),
respectively. Moreover, there was a significant difference in polyphenol contents among different organs of Docynia
longiunguis, which showed the increasing order: pyrene < root < pulp < root bark < peel < stem < leaf. Conclusion: The
established method was simple, stable, accurate, and suitable for the analysis of polyphenols and quality control of Docynia
Dcne.. Docynia Dcne. is widespread and abundant with polyphenols, but there is a significant difference among species and
organs. Accordingly, the plants of this genus have a high value for development and application.

Key words: Docynia Dcne., polyphenol, Folin-Ciocalteu, improved method, determination