Simultaneous determination of four iridoid and secoiridoid glycosides and comparative analysis of Radix Gentianae Macrophyllae and their related substitutes by HPLC

Introduction – Radix Gentianae Macrophyllae, a traditional Chinese medicine, has been frequently used to dispel rheumatism and ease pain. There are four species of Gentiana (G. macrophylla, G. straminea, G. dahurica and G. crassicaulis) recorded as herbal drugs in the Chinese Pharmacopoeia and two other Gentiana species (G. officinalis and G. siphonantha) are often used as substitutes. Currently, the LC fingerprint comparison among different species and evidence for the equivalent application of these herbs are lacking. Objective – To develop an HPLC method for the simultaneous determination of four iridoid and secoiridoid glycosides and a comparative study of six species of Gentiana. Methodology – HPLC analysis was performed on a C₁₈ column (Phenomenex, 150 × 4.6 mm, 5 µm particle size) with gradient elution using 0.4% aqueous phosphoric acid and methanol at 242 nm. Results – The proposed method was precise, accurate and sensitive enough for simultaneous quantitative evaluation of four iridoid and secoiridoid glycosides (loganic acid, swertiamarin, gentiopicroside and sweroside) in the six species of Gentiana. Contents of the four marker compounds varied from each other even among the samples from the same species and the LC chromatograms of the six species of Gentiana showed high similarities. Conslusion – The close similarity of LC chromatograms and chemical composition of the four genuine Gentiana species explain their popular usage as Radix Gentianae Macrophyllae in Chinese medicine. By comparing the four genuine Gentiana species, it is suggested that the two substitutes could be used as Radix Gentianae Macrophyllae to relieve the scarcity of resources. Copyright © 2010 John Wiley & Sons, Ltd.