Abstract:

Objective: The roots, stems, leaves and flowers of Poacynum hendersonii Woodson were compared for
differences in the contents of free and bound phenolics and antioxidant activity, and the correlation between phenolic content
and antioxidant activity was analyzed. Methods: The contents of free and bound phenolics were measured by Folin-Ciocalteu
assay, and the content of total flavonoids by NaNO2-Al(NO3)3 assay. The antioxidant properties were evaluated by 2,2-diphenyl-
1-picrylhydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) free radical
scavenging and reducing power (FRAP, ferric reducing ability of plasma) assays. Results: The total phenolic content in different
parts of Poacynum hendersonii Woodson decreased in the following order: leaves ＞ roots ＞ flowers ＞ stems, with significant
differences among these parts (P ＜ 0.05), and the contents of free, bound and total phenolics ranged from 3 560.19 to 6 273.23,
13.45 to 22.01 and 3 582.20 to 6 286.68 mg gallic acid equivalents (GAE) per 100 g dry weight (md), respectively. The average
percent contribution of free to total phenolics was 99.60%. The contents of free, bound and total flavonoids in the roots, stems,
leaves, and flowers ranged from 1 080.3 to 2 488.21, 9.69 to 28.59 and 1 106.81 to 2 516.8 mg of rutin equivalents (RE)/100 g md
respectively. The average percent contribution of free to total flavonoids was 98.64%. The phenolic extract of the leaves showed
more significant antioxidant activity in radical scavenging and reducing power assays than those of three other parts. There was a
good linear relationship between total phenolics and antioxidant activities (r ＞ 0.950 0). Conclusion: Various parts of Poacynum
hendersonii Woodson are rich in phenolics and possess high antioxidant activity.

Key words: Poacynum hendersonii Woodson, flavonoids, phenolics, antioxidant activity