Accurate mass–time tag library for LC/MS-based metabolite profiling of medicinal plants

Abstract

We report the development and testing of an accurate mass – time (AMT) tag approach for the LC/MS-based identification of plant natural products (PNPs) in complex extracts. An AMT tag library was developed for approximately 500 PNPs with diverse chemical structures, detected in electrospray and atmospheric pressure chemical ionization modes (both positive and negative polarities). In addition, to enable peak annotations with high confidence, MS/MS spectra were acquired with three different fragmentation energies. The LC/MS and MS/MS data sets were integrated into online spectral search tools and repositories (Spektraris and MassBank), thus allowing users to interrogate their own data sets for the potential presence of PNPs. The utility of the AMT tag library approach is demonstrated by the detection and annotation of active principles in 27 different medicinal plant species with diverse chemical constituents.

NMR spectroscopic search module for Spektraris, an online resource for plant natural product identification – Taxane diterpenoids from Taxus×media cell suspension cultures as a case study

“…3D). To obtain independent structural evidence, users can also use HPLC-MS data obtained with high-resolution instruments to search the Spektraris-AMT tag library for natural products (Cuthbertson et al, 2013) or employ MS/MS spectra to search against the MassBank database (Horai et al, 2010) (Fig. 3B).…”

“…Each fraction was evaluated for taxane content (based on signature mass spectral fragmentation patterns) and purity by analyzing an aliquot usingrapid resolution HPLC-QTOF-MS. Where appropriate, factions were combined. If necessary, fractions were subjected to a second HPLC-based fractionation, and these new fractions also analyzed by rapid resolution HPLC-QTOF-MS. For metabolite identification, relative retention times (referenced to anthracene 9-carboxylic acid as an internal standard) and m/z values (determined at high mass accuracy) were compared with those of a taxane authentic standard library (AMT tag approach analogous to Cuthbertson et al (2013) but with a different chromatographic method). In ESI negative polarity mode, taxanes often formed formic acid adducts [M-H + C 1 H 2 O 2 ] - as the base peak, a chloride adduct [M+CI] - , and a smaller [M-H] - ion (Supplementary Table 1).…”

“…Hyphenated techniques, which combine the separation of metabolites by high performance liquid chromatography (HPLC) with online detection by mass spectrometry (MS), have emerged as some of the most versatile analytical approaches. Various searchable online database resources have been developed for HPLC-MS and MS/MS fragmentation data obtained with PNPs (Smith et al, 2005; Horai et al, 2010; Sawada et al, 2012; Cuthbertson et al, 2013; Fukushima and Kusano, 2013). Nuclear magnetic resonance (NMR) spectroscopy is another essential technique, complementary to HPLC-MS, for PNP structure elucidation.…”

“…A re-isolation or re-synthesis of a larger number of PNPs is not practical. The Spektraris toolbox (http://langelabtools.wsu.edu/Spektraris), which until now focused on HPLC-MS data sets for PNPs (based on the accurate mass-time tag approach; Cuthbertson et al, 2013), was thus expanded to include a searchable database for NMR spectroscopicdata that were extracted from the literature. As a proof-of-concept, the utility of the Spektraris-NMR resource was tested to identify various taxanes, which belong to a structurally complex family of diterpenoid metabolites commonly found across the genus Taxus (yew).…”

Metabolite Profiling Analysis of Conventional and Non-Conventional Extraction Methods on Secondary Metabolite from Peperomia pellucida (L.) Kunth Using UPLC-QToF-MS/MS System

“…The potential for chemical screening strategies has been significantly enhanced by the recent development of the hyphenated technique, which is capable of generating efficient metabolite separation, along with valuable structural information both online and at-line. 16 One of the instruments with the hyphenated system used to analyze metabolite profiling with high accuracy and validity [17][18] from crude extract is UPLC-QToF-MS/MS tandem system. 19 20 Analysis of steviol and its glycoside from Stevia rebaudiana leaves as a commercial sweetener, 21 metabolite profiling of polyphenols from Vaccinium berries.…”