Determination and locational variations in the quantity of hydroxyanthraquinones and their glycosides in rhizomes of Rheum emodi using high-performance liquid chromatography

Abstract

Locational variations in the quantity of five hydroxyanthraquinone derivatives (emodin glycoside ( 1), chrysophanol glycoside ( 2), emodin ( 3), chrysophanol ( 4) and physcion ( 5)) in the rhizomes of Rheum emodi are described. A simple and reliable method was developed for quantitation of compounds ( 1– 5) in the methanolic extract of rhizomes of R. emodi using reverse-phase high-performance liquid chromatography (HPLC) with photo-diode array detector (PDA). The separation was carried out using a Purospher ®-Star RP-18e column (4.6 mm i.d. × 250 mm, 5 μm) under the following conditions: acetonitrile:methanol (95:5, v/v) (solvent A) and water:acetic acid (99.9:0.1, v/v) (solvent B) as mobile phase with a linear gradient elution at a flow rate of 0.8 mL/min. The detection wavelength was set at 290 nm. Regression equation revealed a linear relationship ( r 2 > 0.9901) between the mass of hydroxyanthraquinone derivatives injected and the peak areas. The detection limits ( S/N = 3) ranged from 0.56 to 3.50 ng/mL and the recoveries ranged from 95.7 to 103.5% for five hydroxyanthraquinone derivatives. Compound 2 was found in maximum quantity (up to 2.23%) in the rhizomes from all the three locations (L 1, L 2 and L 3) while compound 5 was found in the least quantity (up to 0.19%).