Studies on Crude Drugs originated from Gentianaceous Plants. I. Determination of Gentiopicroside, the Bitter Principle of Gentianae Radix and Gentianae Scabrae Radix

Abstract

Two new methods for the determination of gentiopicroside in gentian radix and Gentiana scabra radix were developed by the combination of TLC and spectrophotometry. In the preparative TLC-UV method, gentiopicroside contained in the methanol extract of samples is quantitatively separated by preparative TLC (detection by a PAN UV lamp) and the amount is determined from the absorbance at 270 nm by using a calibration graph. In the TLC-densitometer method, the methanol extract containing gentiopicroside is developed on the TLC plate, and the amount of gentiopicroside (Rf = ca. 0.4) is measured by TLC densitometry using a dual-wavelength TLC scanner. By these 2 methods, the content of gentiopicroside was determined as 1-2% in gentian radix (Osaka market product), 1-3% in G. scabra radix (Osaka market product), and 7-10% in the fresh root of G. scabra Bunge.