Determination of Dried Root Extract of Rheum emodi and its Commercial Products Using Rhein and Chrysophanol as Standard Markers by HPTLC Densitometric Analysis

Background: Standardization and quality control of medicinal plants and their commercial products are one of the critical needs for ensuring their quality, safety and efficacy which assists in validation as well as regulation of herbal medicines and their herbal products. Rheum emodi, Himalayan rhubarb or Revand chini is a perennial, traditional Indian medicinal herb from family Polygonaceae, used as laxative, tonic, diuretic and to treat fever, cough, indigestion, menstrual disorder. Emodin, aloe-emodin, rhein and chrysophanol are the anthraquinones found in high concentration in this plant. Objectives: The present study aimed at qualitative and quantitative estimation of rhein and chrysophanol in the methanolic extract of Rheum emodi roots and its commercial products by HPTLC densitometric analysis which has not been reported in the literature so far. Materials and Methods: The separation and quantification of rhein and chrysophanol was performed on pre-coated Silica gel 60 F254 HPTLC plates using Toluene: Ethyl Acetate: Glacial Acetic Acid (6:3.5:0.5, v/v/v) as mobile phase. The quantification of rhein and chrysophanol was carried out at 254nm and 366nm using Camag TLC scanner III using Wincats1.2.3 software. Results: The developed method was linear, accurate, precise, robust and specific and was found to be more sensitive to chrysophanol than the reported method of Singh et al. The proposed method was linear from 100 to 2000 ng. The limit of detection and quantification were found to be 18.915±0.754, 15.849±0.839 ng/spot and 57.318±1.162, 48.028±1.007 ng/ spot for rhein and chrysophanol respectively. The content of rhein and chrysophanol was found to be 108.002±0.323 and 67.143±0.0884 μg/mg in Rheum emodi root extract, 26.829±0.138, 1.652±0.0031 μg/mg in marketed formulation 1 and 123.691±0.758, 30.476±0.0884 μg/mg in marketed formulation 2. Conclusion: The developed method can have great application for standardization of herbal formulations and commercial products containing R. emodi plant extract in the herbal industry.