Estimation of Aloe-emodin Content in Cassia grandis and Cassia garrettiana Leaves Using TLC Densitometric Method and TLC Image Analysis

Abstract

Plants in genus Cassia contain anthraquinones that possess stimulant laxative property. Cassia grandis L.f. and Cassia garrettiana Craib have been widely distributed throughout Thailand as Thai herbal medicine and ornamental plant. The objective of this study was to develop and validate TLC densitometry and TLC image analysis for quantitative analysis of aloe-emodin content in Cassia grandis and Cassia garrettiana leaves. The fresh mature leaves of Cassia grandis and Cassia garrettiana, collected from 15 locations throughout Thailand were successively extracted with dichloromethane. Silica gel 60 GF254 was used as a stationary phase and hexane-ethyl acetate (1:1, v/v) was used as the mobile phase. Aloe-emodin contents estimated using TLC densitometry and TLC image analysis in Cassia grandis dried crude drug were 0.4122±0.0668 and 0.4130±0.0751 g % and Cassia garrettiana dried crude drug were 0.0346±0.0067 and 0.0351±0.0056 g %, respectively. The method was validated in terms of calibration range, accuracy, repeatability and intermediate precision, limit of detection, limit of quantitation, specificity and robustness. A statistical comparison of the quantitative analysis using TLC densitometry and TLC image analysis of aloe-emodin in Cassia grandis and Cassia garrettiana leaves were not statistically significant (p>0.05). Both validated methods can be used for evaluation of aloe-emodin contents in C. grandis and C. garrettiana leaves.