Evaluation of the Phenolic Content in the Buds of Polygonum cuspidatum Sieb. et Zucc.

Abstract

Polygonum cuspidatum Sieb.et Zucc. (Japanese knotweed) is considered an invasive plant in several countries in Europe, whilst being used in the Traditional Chinese Medicine for various inflammatory diseases, hepatitis, tumors, diarrhea, suppurative dermatitis, gonorrhea, hyperlipidemia, favus athlete’s foot, osteomyelitis. The present study is focused on the characterization of different extracts of Polygonum cuspidatum Sieb.et Zucc. buds, by determination of the influence of different solvents on the extraction yield, the phenolic content and their antioxidant capacity. The solvents used were ethanol, propylene glycol, methanol, acid water and alkaline water, in different combinations. The UV-Vis spectra were recorded and the total phenolic content was determined by Folin-Ciocalteu colorimetric method, comparing the extraction yields with the total phenolic contents. The antioxidant activity was evaluated by 1,1-diphenyl-2-hydrazyl (DPPH) assay. The extracts analyzed had total phenolic values from 1048 mg/100g to 1426 mg/100g fresh buds, expressed as gallic acid equivalents, the highest extraction index being 96.3, in good agreement with the antioxidant capacity. These data suggest that Polygonum cupidatum Sieb.et Zucc. buds could be a rich source of natural antioxidants and a good candidate as an ingredient in functional food, cosmetics and drugs for the prevention of the negative effects of oxidative stress on humans.