Multipronged Approach to Profiling Metabolites in Beta vulgaris L. Dried Pulp Extracts Using Chromatography, NMR and Other Spectroscopy Methods

Joshua Fiadorwu; Kiran Subedi; Daniel Todd; Mufeed M Basti

doi:10.3390/foods12183510

Multipronged Approach to Profiling Metabolites in Beta vulgaris L. Dried Pulp Extracts Using Chromatography, NMR and Other Spectroscopy Methods

Foods. 2023 Sep 21;12(18):3510. doi: 10.3390/foods12183510.

Authors

Joshua Fiadorwu¹, Kiran Subedi², Daniel Todd³, Mufeed M Basti¹

Affiliations

¹ Department of Applied Science and Technology, College of Science and Technology, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA.
² Analytical Services Laboratory, College of Agriculture and Environmental Sciences (CAES), North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA.
³ Triad Mass Spectrometry Facility, University of North Carolina at Greensboro, Greensboro, NC 27412, USA.

Abstract

Beetroot (Beta vulgaris L.) is known for being a rich source of phytochemicals, minerals and vitamins. This study aims to show how the combination of extraction/chromatography/mass spectrometry and NMR offers an efficient way to profile metabolites in the extracts of beetroot. Such combination may lead to the identification of more nutritional or medicinal compounds in natural products, and it is essential for our ongoing investigation to study the selective adsorption/desorption of these metabolites' on/off nanoparticles. The aqueous and organic extracts underwent analyses using UV-vis spectroscopy; GC-MS; LC-MS; ¹H, ¹³C, ³¹P, TOCSY, HSQC, and selective TOCSY NMR experiments. Polar Extract: The two forms of betalain pigment were identified by UV-vis and LC MS. Fourteen amino acids, sucrose, and other compounds, among which is riboflavin, were identified by LC-MS. Two-dimensional TOCSY showed the spin coupling correlations corresponding to some of these compounds. The HSQC spectrum showed ¹H/¹³C spin correlation in sucrose, confirming its high abundance in beetroot. Organic Extract: GC-MS data enabled the identification of several compounds including six fatty acid methyl esters (FAME) with higher than, on average, 90% similarity score. Selective TOCSY NMR data showed the spin coupling pattern corresponding to oleic, linoleic, and linolenic fatty acids. ³¹P NMR spectra indicate that phospholipids exist in both the organic and aqueous phase.

Keywords: Gas Chromatography-Mass Spectrometry (GC-MS); Total Correlation Spectroscopy (TOCSY); beetroot (Beta vulgaris L.); fatty acid methyl esters (FAME); homonuclear single quantum correlation (HSQC); selective TOCSY.

Grants and funding

This research received no external funding. The dean of the College of Science and Technology and the director of the Applied Science and Technology program offered financial support to Mr. Fiadorwu.