Development and Validation of Improved HPLC Method for the Quantitative Determination of Curcuminoids in Herbal Medicament

Abstract

A simple and precise high performance liquid chromatography (HPLC) method was developed and validated for simultaneous trace analysis of the content of pharmacologically important active curcuminoids: curcumin (C), demethoxycurcumin (DMC) and bisdemethoxy curcumin (BDMC) in a novel standardized herbal preparation derived from the hexane soluble extract of Curcuma longa, tentatively assigned the generic nomenclature “herbal medicament” (HM). HPLC separation of active constituents was achieved on a Chromolith (100 x 4.6 mm, 2 µm, Merck) column using water-acetonitrile-acetic acid (60:40:1, v/v/v) as mobile phase, with UV detection at 425 nm. The method was validated for linearity, limit of detection (LOD), limit of quantification (LOQ), robustness, recovery, precision and accuracy. An empirical equation enabling calculation of the percentage content of DMC and BDMC from a calibration curve of C, without relying on reference standards of DMC and BDMC, is proposed on the basis of available evidence, suggesting that pharmacologically important curcuminoids may be accurately reported as proportions of a single constituent assayed quantitatively. Hence, quantitative estimation of trace constituents on the basis of empirical evidence for proportionate composition is suggested as a means of quantifying the key constituents in herbal preparation intended for pharmacological intervention in patients requiring treatment with HM.