Profiling of metabolite content of Moringa oleifera leaf samples using solid-state 13C NMR

Abstract

International audienceMoringa oleifera (MO) is a multipurpose tree widespread in tropical countries. Many studies have shown that MO leaves have a high nutritional value and a wide range of biological activities [1,2]. Numerous products derived from MO leaf powders (MOLP) are easily available and without quality control. The aim of this study was to find a rapid method to control the quality of MOLP. Solid-state 13C NMR associated to multivariate analysis applied on MOLP samples from various geographic origins have shown that it is possible to discriminate samples on the basis of relative areas calculated from specific spectral NMR regions [3]. Principal Component (PC) Analysis on NMR data allowed to differentiate samples according to PC1 and PC2 (with 65% and 25% of explained variance respectively). The signal of alkyl carbons was assigned to lipids; O-alkyl and di-O-alkyl carbons signals were mainly attributed to carbohydrates and polysaccharides while methoxyl carbons came from polysaccharides and lignin. Aromatic and phenolic carbons signals were attributed to lignin and amino acids while carboxyl carbon signals were assigned to esters or acids along with carbon atoms from the peptide bond. Samples from Egypt, Cameroon and Burkina Faso appeared to be richer in carbohydrates and polysaccharides according to PC1, whereas samples from Chad, Indonesia and Dominican Republic were characterized by a highest lipid and lignin content. According to PC2, both sample sets from Burkina Faso and Cameroon presented one sample with relatively high phenolic and aromatic contents. While this approach could not give absolute metabolite content, it appeared to be efficient to classify different MOLP and select their provenance in order to choose a particular sample considering phytochemical and/or pharmacological interests and furthermore to ensure a consistent quality of the material