Determination of Polyphenol Content in Houttuynia cordata Thunb. by Folin-Ciocalteu Colorimetric Method

Objective: To establish a quantitative method to assay total polyphenols in Houttuynia cordata Thunb..Method: Four solvents (methanol,ethanol,acetone and water) were used to extract Houttuynia cordata Thunb.with the assistance of ultrasonic in order to explore the effects of extraction solvent type and length of extraction on the extraction of total polyphenols.Subsequently,the 2 h ethanol extract was used to optimize 20% sodium carbonate amount,Folin-Ciocalteu regent amount,reaction temperature and length of reaction.Results: Methanol was the best extraction solvent,followed by ethanol,acetone and water.The optimum conditions for determining total polyphenols in Houttuynia cordata Thunb.were as follows: a mixture of 0.5 mL of methanol extract,2.0 mL of 20% sodium carbonate and 1.5 mL of Folin-Ciocalteu reagent diluted with distilled water to 50.0 mL for incubation at 55 ℃ for 1.5 h,followed by detection at 760 nm.Conclusion: The method is simple,accurate and provides an appropriate method for measuring total polyphenols in Houttuynia cordata Thunb.