Simultaneous quantitative and qualitative analysis of bioactive phenols in Dendrobium aurantiacum var. denneanum by high-performance liquid chromatography coupled with mass spectrometry and diode array detection.

A novel high-performance liquid chromatographic method with mass spectrometry and diode array detection method for the simultaneous qualitative and quantitative analysis of bioactive phenols was developed. In total, nine chemically diverse phenols including five bibenzyls, three phenanthrenes and a coumarin were unambiguously identified in Dendrobium aurantiacum var. denneanum by comparison with the available references or reported data according to their retention behaviors, UV spectra and fragmentations of ESI-MS. The contents of the four main phenolic compounds, moscatilin, gigantol, moscatin and coumarin, in D. aurantiacum var. denneanum from the wild and various cultivated populations were determined by HPLC-UV. The sample preparation involved a rapid and simple procedure based on solid-phase extraction using a C(18) reversed-phase cartridge. The quantitative analysis was performed on a Beckman Coulter ODS column (5 microm, 250 x 4.6 mm) using a linear gradient elution system of acetonitrile-0.5% formic acid. The method was validated for linearity, limits of detection (LOD) and quantification (LOQ), precision and accuracy. Good results were obtained with respect to the overall intra- and inter-day variations (RSD less than 3.22%) and the percentage recoveries (ranging from 90.50 to 99.22%). Notable differences in the contents of phenols were observed among different cultivated populations. The samples colleted in April and May (spring), or October and November (autumn) accumulated much higher contents of phenols than those collected in other seasons.