Metabolite Fingerprinting of Kersting's Groundnut [Macrotyloma geocarpum (Harms) Maréchal & Baudet] Seeds Using UPLC-qTOF-MS Reveals the Nutraceutical and Antioxidant Potentials of the Orphan Legume

Abstract

The identification and subsequent quantification of phenolic compounds in plants is the first step toward harnessing their associated nutritional and health benefits. Due to their diverse phenolic compound compositions, grain legumes are known for their high nutritional and health values. The aim of this study was to assess the inter-variations in chemical composition, phytochemical content, and antioxidant capacity of seed extracts from eight Kersting's groundnut [Macrotyloma geocarpum (Harms) Marechal & Baudet] landraces. The chemical profiles were evaluated using UPLC-qTOF-MS. Total phenolics and flavonoids content were determined by the Folin-Ciocalteu and aluminum chloride methods, respectively. The antioxidant capacities in the forms of DPPH and ABTS were evaluated using spectrophotometric methods. Principal component analysis was used to define similarities/differences between the landraces. Based on untargeted metabolomics analysis, 57 metabolites were identified, with phenolics, triterpenes, fatty acids, and sphingolipids being the most predominant. The results showed that the black seeded KG1 (Puffeun) had the highest total phenolic (9.44 mg GAE/g) and flavonoid (3.01 mg QE/g) contents, as well as antioxidant capacity (9.17 μg/mL and 18.44 μg/mL based on DDPH and ABTS assays, respectively). The concentrations of ferulic acid hexoside, procyanidin B2, eryodictyiol-7-rutinoside and quercetin pentoside ranged from 51.78–441.31, 1.86–18.25, 3.26–13.95 to 5.44–63.85 μg/mg, respectively. This study presents a useful report on the phytochemical characterization of Kersting's groundnuts and shows that the grains can be used as a source of nutraceuticals for human consumption.

Black Seedcoat Pigmentation Is a Marker for Enhanced Nodulation and N2 Fixation in Bambara Groundnut (Vigna Subterranea L. Verdc.) Landraces

“…This argument is supported by the findings of Hungria and Phillips (1993) who also showed that a black-seeded common bean genotype that released higher concentrations of nod-geneinducing flavonoids elicited greater nodulation than its isogenic cream genotype with reduced biosynthesis of the flavonoid nodgene inducers. Therefore, the markedly higher concentrations of anthocyanins and flavonoids found in the seedcoats of black cowpea and Bambara groundnut landraces (Tsamo et al, 2019(Tsamo et al, , 2020 probably induce greater nod-gene expression in the microsymbionts of these species, leading to increased nodulation and N 2 fixation, as found in this study (Tables 4, 5).…”

“…Seedcoat pigmentation is reported to be a major determinant of the profile and concentrations of flavonoids, anthocyanins and anthocyanidins in cowpea, Bambara groundnut and Kersting's groundnut seeds (Tsamo et al, 2018(Tsamo et al, , 2019(Tsamo et al, , 2021. Based on metabolite profiling of cowpea seed coats, as well as Bambara groundnut and Kersting's bean seeds, Tsamo et al (2020) found black seeds of legumes to be a natural source of nutraceuticals for human consumption, and a reservoir of anthocyanins that can be exploited for developing cosmetic, food and pharmaceutical products.…”

“…The Black and Red landraces also generally recorded lower shoot δ 15 N values, derived a higher proportion of their N from fixation, and produced more symbiotic N. Anthocyanidins and their anthocyanin aglycones from black-seeded common bean have been reported to be potent inducers of nodulation genes in symbiotic rhizobia (Hungria et al, 1991). We therefore attribute the superior symbiotic performance of the Black Bambara groundnut landrace to its ability to produce and release higher concentrations of nodgene-inducing anthocyanins and flavonoids than its Red and Cream counterparts (Table 2; Tsamo et al, 2018Tsamo et al, , 2019Tsamo et al, , 2020. This argument is supported by the findings of Hungria and Phillips (1993) who also showed that a black-seeded common bean genotype that released higher concentrations of nod-geneinducing flavonoids elicited greater nodulation than its isogenic cream genotype with reduced biosynthesis of the flavonoid nodgene inducers.…”

Nutritional, functional, and bioactive properties of african underutilized legumes

“…Legume seeds contain significant amounts of antioxidants due to their high phenolic, flavonoid, and anthocyanin contents. Consuming products made from these legumes may help prevent and manage various chronic and degenerative diseases, as well as address proteincalorie malnutrition (Foyer et al, 2016;Tsamo et al, 2020;Popoola et al, 2022a). Studies by Adefegha and Oboh (2012); Kennedy (2014); Adefegha et al (2017); Gupta and Prakash (2019), and Adefegha (2018) have confirmed that these bioactive components of NULs could play significant roles in increasing the immune level and support prevention of common diseases such as malnutrition (severe and acute particularly in infants), sexual enhancers, obesity, diabetes, heart-related diseases amongst others.…”

Evaluation of the effect of substrates and types of wheat flour on microbiological characteristics, pH values, levels of total phenolic compounds, antioxidant capacity and fermentative capacity of sourdough

“…Phenolic compounds are hydroxylated substances naturally found in foods (Achkar et al, 2013). They are of plant origin (Tsamo et al, 2020), having a pigmentation function (Singh et al, 2019), free radical removal (Koley et al, 2014) and light absorption in plants (Naczk & Shahidi, 2004). The value of phenolic compounds for sourdoughs is related to larger wheat flour, being considered a source of phenolic compounds (Sivam et al, 2010).…”