Investigation into the antioxidant and antidiabetic potential of Moringa stenopetala: identification of the active principles.

The fresh leaves of Moringa stenopetala (family, Moringaceae) are commonly eaten as cabbage while dried leaves are used as nutritional supplement and for treating a variety of disease conditions including diabetes. The present investigation into the therapeutic potential of the leaves and seeds of the plant revealed no inhibitory effect against α-glucosidase enzyme up to the concentration of 200 μg/mL but the leaves extract displayed potent DPPH (1,1-diphenyl-2- picrylhydrazyl) radical scavenging effect (IC50, 59.5 ± 4.1 μg/mL). An activity directed fractionation and isolation procedure resulted in the identification of the major antioxidant compound as rutin and minor active component, neochlorogenic acid. Both the crude extract (0.8-200 μg/mL) and rutin (0.8-200 μM) but not neochlorogenic acid displayed a concentration-dependent protection of human pancreatic β-cells (1.4E7 cells) from oxidant-induced cell death. The identification of these compounds along with their potential role in the nutritional and medicinal significance of the plant is discussed.