Determination and Comparison of Emodin in Six Kinds of Polygonaceae Herbs

Objective:To determine and compare emodin in six kinds of polygonaceae herbs.Methods:The sample solutions were prepared by ultrasonic extraction.HPLC method was used to determine emodin in polygonaceae herbs.Zorbax XDB-C18 column was used and the mobile phase was CH3OH-1% CH3COOH(70∶ 30).The detection wavelength was 254nm,the flow rate was 1.5 mL·min-1,the column temperature was 40℃,and the injection volume was 20μl.Results:Emodin showed a good linear(r=0.9995)relationship at the range of 1μg·mL-1~500μg·mL-1,and its average recovery rate was 97.56%(RSD=2.72%,n=6).The contents of emodin in rhizomes and roots of Polygonum cuspidatum Sieb.et Zucc.were 22.965mg·g-1 and 16.285mg·g-1.The contents of emodin in rhizomes and roots of Rumex acetosa L.were 2.5966 mg·g-1 and 2.7204 mg·g-1.The contents of emodin in rhizomes and roots of Fagopyrum dibotrys(D.Don) Hara were 0.029 mg·g-1 and 0.0682 mg·g-1.The contents of emodin in rhizomes and roots of Rumex japonicus Houtt.were 1.4634 mg·g-1 and 1.5796 mg·g-1.The contents of emodin in Caulis Polygoni Multiflori(3 years) was 3.367 mg·g-1.The contents of emodin in roots of Polygonum multiflorum Thunb.was 2.0947 mg·g-1.Conclusion:The method is suitable for the determination of emodin in polygonaceae herbs.The contents of emodin in rhizomes and roots of Polygonum cuspidatum Sieb.et Zucc.were higher than in other five polygonaceae herbs.And the rhizomes and roots of Polygonum cuspidatum Sieb.et Zucc.are ideal raw medicinal materials for extracting emodin.