Combined Application of UHPLC-QTOF/MS, HPLC-ELSD and H-1-NMR Spectroscopy for Quality Assessment of DA-9801, A Standardised Dioscorea Extract

Abstract

Introduction - DA-9801, a standardised 50% aqueous ethanolic extract of a mixture of Dioscorea japonica and D. nipponica, is a botanical drug candidate for the treatment of diabetic neuropathy, which finished its US phase II clinical trials recently. An advanced quality control method is needed for further development of DA-9801, considering its high contents of both primary and secondary metabolites. Objective - Development of a quality assessment strategy for DA-9801, based on the combination of UHPLC-QTOF/MS, HPLCELSD, and 1H-NMR spectroscopy.

Methods - The method was developed and tested with 15 batch products of DA-9801. The steroidal saponins of DA-9801 were tentatively identified by UHPLC-QTOF/MS and were quantified with the validated HPLC-ELSD method. Primary metabolites of DA-9801 were identified and profiled using 1H-NMR spectrometry. The batch-to-batch equivalence of DA-9801 was tested with the H-1-NMR spectra using spectral binning, correlation analysis, and principal component analysis.

Results - Six major saponins of DA-9801 were tentatively identified by UHPLC-QTOF/MS. Among them, protodioscin and dioscin were quantified by the validated HPLC-ELSD method. Twenty-six metabolites were identified in H-1-NMR spectra. The similarity between DA-9801 batches could be evaluated with the NMR spectra of D