Abstract:

Objective: To investigate the simultaneous extraction of resveratrol and emodin from the fruits of Polygonum
cuspidatum and to compare their contents with those of the rhizomes of male, non-bearing and bearing female plants.
Methods: High performance liquid chromatography (HPLC) was used to determine the contents of resveratrol and emodin.
The microwave-assisted extraction of resveratrol and emodin was carried out using aqueous ethanol as extraction solvent.
Microwave firepower, ethanol concentration, solid-to-solvent ratio and extraction time, all of which were found to influence
extraction efficiency, were optimized by using orthogonal array experiments. Comparison of the contents of resveratrol and
emodin in the fruits and rhizomes of Polygonum cuspidatum was performed. Results: The optimal extraction conditions
were obtained as follows: ethanol concentration, 70% (V/V); solid-to-solvent ratio, 1:20 (g/mL); microwave power, 800 W;
microwave irradiation for 3 min at firepower 40 and for additional 3 min at firepower 60 after cooling; and extraction time,
6 min. The contents of resveratrol and emodin in the rhizomes of male and non-bearing female plants were significantly
higher than those of the rhizomes of female plants and fruits of Polygonum cuspidatum, and all these values exceeded those
specified in the Chinese Pharmacopoeia. The extraction process presented in this study was reasonable, stable and feasible.
Differences in the contents of resveratrol and emodin existed among three types of rhizomes and fruits of P. cuspidatum.
However, the fruit has the potential for development and utilization.

Key words: Polygonum cuspidatum, resveratrol, emodin, extraction process, HPLC