Nutritional and antioxidant properties of South American Moringa stenopetala

Abstract

Moringa stenopetala is a tropical tree from the Moringaceae family, native to north-east Africa, that has widespread to many countries. It is highly valued for the associated nutritional and medicinal properties. The nutritional value of South American Moringa stenopetala was assessed in this work, giving some deeper insight into the expected biological accessibility of the main nutrients present in raw leaves and prepared infusions. Metal ions were determined by FAAS; L-ascorbic acid, leucine, and tryptophan by LC-DAD; rutin, isoquercitrin and neochlorogenic acid by LC-ESI-MS/MS. Metal ions content in analyzed specimens was in the same order of previously reported data, except for lower values for iron, probably associated to the different soil composition. Tested amino acids were also found in the previously reported range, while higher contents of L-ascorbic acid, rutin and neochlorogenic acid were determined. Interestingly, transfer factors to infusions resulted especially low for magnesium, calcium, iron, and L-ascorbic acid, indicating that the way of consumption exerts a strong influence on the nutritional value of the vegetal material. Chemical speciation modeling experiments to predict bioaccessibility showed that sodium, potassium, magnesium, and calcium ions to be predominantly free. On the other hand, the micronutrients are predicted to be partly associated to polyphenolic compounds. Finally, the antioxidant activity was studied both in the vegetal material and the prepared infusions by the ORAC assay, both showing relevant antioxidant activity probably associated to the high rutin content. This biomolecule, together with other polyphenolic compounds present, are expected to partially retain metal ions in solution, also contributing to the antioxidant beneficial properties of Moringa stenopetala.