From 1H NMR-based non-targeted to LC-MS-based targeted metabolomics strategy for in-depth chemome comparisons among four Cistanche species

Abstract

The great orthogonality between ¹H NMR spectroscopy and LC-MS implies that their deployments in series could offer an opportunity to gain the qualified molecular markers via comparative metabolomics, and an attempt was made here to propose an integrated strategy namely "from ¹H NMR-based non-targeted to LC-MS-based targeted metabolomics". In-depth chemome comparisons of Cistanche plants, such as C. deserticola, C. salsa, C. tubulosa, and C. sinensis, that possess dramatic economic and ecological benefits for the arid regions in the northwest China attributing to their dramatic medicinal and edible values, were employed to verify the applicability. ¹H NMR-based non-targeted matabolomics acted as the survey experiment to find those signals offering decisive contributions towards the species discrimination, and the signals were translated to a set of putative identities, eighteen ones in total, through matching with authentic compounds and referring to some accessible databases. Afterwards, an advanced LC-MS platform assembling reversed phase liquid chromatography, hydrophilic interaction liquid chromatography, and tailored multiple reaction monitoring, was introduced to simultaneously quantify those eighteen potential markers in a single analytical run, because those candidates exhibited great polarity span as well as wide content range. Significant species differences occurred amongst their chemome patterns. Echinacoside, acteoside, betaine, mannitol, 6-deoxycatalpol, sucrose, and 8-epi-loganic acid were disclosed as the markers enabling the discrimination of those four species. The findings offered an alternative tool to differentiate Cistanche plants. More importantly, the strategy namely "from ¹H NMR-based non-targeted to LC-MS-based targeted metabolomics" facilitates the pursuit of molecular markers among analogue plants, and thereby provides a promising choice for in-depth chemome comparison.

Keywords: (1)H NMR-based non-targeted metabolomics; Chemome comparison; Cistanche plants; LC–MS-based targeted metabolomics; Species differences.