Tissue-Specific Metabolic Profile Study of Moringa oleifera L. Using Nuclear Magnetic Resonance Spectroscopy

Abstract

Moringa oleifera, an important multipurpose crop, is rich in various phytochemicals: flavonoids, antioxidants, vitamins, minerals and carotenes. The purpose of this study was to profile the groups of metabolites in leaf and stem tissues of M. oleifera. Various sugars, amino acids, and organic acid derivatives were found in all of the M. oleifera tissues with different profiles/peak intensities depending on the tissue. 1D proton nuclear magnetic resonance (NMR) was applied for collecting metabolite spectra. Approximately 30 metabolites with 2 unknown peaks were identified with Chenomx and verified with MMCD databases using carbon data. Among these metabolites, 22 metabolites were identified as common in both leaf and stem tissues. Of the remaining 8 metabolites, 4-aminobutyrate, adenosine, guanosine, tyrosine, and p-cresol were found only in leaf tissues; however, glutamate, glutamine, and tryptophan were found only in stem tissues. Biochemical pathway analysis revealed that 28 identified metabolites were interconnected with 36 different pathways as well as related to different fatty acids and secondary metabolites synthesis biochemical pathways. It is well known that different tissues of M. oleifera have nutritional, medicinal, and therapeutic values; therefore, our main objective is to provide a publicly available M. oliefera tissue specific metabolite database.

NMR-Based Metabolomic Analyses to Identify the Effect of Harvesting Frequencies on the Leaf Metabolite Profile of a Moringa oleifera Cultivar Grown in an Open Hydroponic System

“…In addition, these metabolites are associated with known important medicinal properties, and their presence in M. oleifera leaf extract has been widely reported. As indicated in Table 2 , the targeted compounds were identified using the NMR chemical shifts as previously published [ 4 , 6 , 24 , 26 , 28 , 29 , 30 , 31 , 32 ], assisted by databases such as Chenomx profiler and the Human Metabolome Database ( Supplementary Table S1 ). Annotation of chlorogenic and GABA were further confirmed through spiking with commercial standards.…”

“…Thus, the effect of various biotic and abiotic factors on the accumulation of secondary metabolites could be efficiently determined with metabolomics technology. 1 H-NMR spectroscopy is particularly a good choice in plant metabolomics studies given the universal occurrence of protons in organic metabolites, and can be successfully applied in moringa plant research [ 22 , 23 , 24 ]. It enables analyses of complex samples such as herbs and phytomedicines without separation but with good accuracy and consistency based on the entire chemical composition of the samples.…”

“…It enables analyses of complex samples such as herbs and phytomedicines without separation but with good accuracy and consistency based on the entire chemical composition of the samples. In principle, 1 H-NMR provides a reliable profile of each raw material sample, and quantities are reflected in the integrals of the individual signals of the spectrum [ 24 , 25 ].…”

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“…The stem bark contains two alkaloids, known as moringine and moringinine 17 . Moreover, compounds like β-sitosterol, vanillin, βsitostenone, 4-hydroxymellin and octaicosanoic acid have also been extracted from the stem of M. oleifera 18 . Flowers of M. oleifera is found to contain nine amino acids, D-glucose, sucrose, wax, traces of alkaloids, quercetin and kaempferol, while ash is rich in potassium and calcium 19 .…”

Chemical profiling and chemical standardization of Vitex negundo using 13C NMR

“…NMR is robust, highly reproducible, and requires minimal sample preparation which minimizes experimental artifacts and bias. Because of the desire for highest sensitivity, 1H NMR is the most common technique used and is combined with chemometric methods to profile, fingerprint or discriminate among crude herbal samples (Bailey et al, 2002;Zulak et al, 2008;Lee et al, 2009;Kim et al, 2010;Mahmud et al, 2014), and for quality control (Wang et al, 2004, Rasmussen et al, 2006, van der Kooy et al, 2008. 1H NMR measurements of herbal medicines have been reported using magnetic fields from 300 to 800 MHz (Zulak et al, 2008;Kim et al, 2011).…”