Metabolite profiling of different solvent extracts of Moringa oleifera seeds and correlation with DPPH radical scavenging activity via 1H NMR-based metabolomics

Abstract

In the present study, profiling of the Moringa oleifera seeds metabolome was carried out by employing proton nuclear magnetic resonance (1H NMR) spectroscopy combined with multivariate data analysis (MVDA) of 3 different solvent extracts. The principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) score plot reveal that methanol extract was discriminated from ethyl acetate and hexane extracts by PC1 while ethyl acetate and hexane extracts were well separated from methanol extract by PC2. The PLS-DA loading plot highlighted the potential metabolites, which are responsible for the group separation observed in the score plot. Further detailed examination of the loading plot shows that methanol extract contains significantly higher amount of vitamins, sterols, amino acids and fatty acids compared to the other extracts. A total of 37 compounds were detected from the 3 different solvents upon which the methanolic extract was identified to contain more metabolites and in a wider range than the other organic solvent extracts. Based on PLS analysis, ergosterol, oleic acid, isoleucine, riboflavin, cholesterol, leucine, ascorbic acid, stigmasterol, tryptophan, choline, histidine and cysteine displayed strong correlation to 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity. Hence, this extract would be more appropriate in metabolite extraction for analysis and for therapeutical benefits. Therefore, NMR spectroscopy combined with MVDA in compliment with the right choice of solvent for extraction could be utilized by applicable industries to obtain maximum valued metabolites within a short period of time. Besides having high diversity of metabolites, M. oleifera seeds can serve as potential nutritional source to develop new functional foods, and even as a source of biodiesel. Key words: Moringa oleifera seeds, functional food, biofuel, metabolome, 2,2-diphenyl-1-picrylhydrazyl (DPPH), multivariate data analysis, 1H NMR metabolomics.