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

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 (r2 > 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 (L1, L2 and L3) while compound 5 was found in the least quantity (up to 0.19%).