High-performance thin-layer chromatography/bioautography and liquid chromatography-mass spectrometry hyphenated with chemometrics for the quality assessment of Morus alba samples

Quality control is a crucial step in the production of effective and safe herbal remedies. The aim of this study was to develop a new, simple, and high throughput procedure for the quality assessment of herbal drugs using a high-performance thin-layer chromatography (HPTLC)/bioautography and UPLC–MS/MS approach combined with chemometrics. This was exemplarily shown for Morus alba L. root bark (sāng bái pí; SBP). Bioautography assays were developed for the identification of constituents with radical scavenging (DPPH assay) and antimicrobial activities (Bacillus subtilis, Escherichia coli) of 18 different M. alba samples, which was supported by UPLC–MS/MS analysis. Further, the combination of bioautography and chemometrics identified those samples with the most bioactive constituents. Plant materials collected from Serbia (11 samples) showed higher both radical scavenging and antimicrobial activities compared to samples provided from China (7 samples). Principal component analysis (PCA) confirmed the discrimination of geographically different samples and recognized their main markers responsible for differences between Serbian and Chinese samples. Most importantly for quality assessment, the combined HPTLC/bioautography and UPLC–MS/MS approach not only allowed for a fast chemical profiling of the investigated samples and their unambiguous identification, but also for the disclosure of major and minor bioactive constituents present in SBP.