Antioxidant activity of Moringa oleifera isothiocyanates
Moringa oleifera Lam. (Brassicales) is an edible tropical tree with medicinal properties. Here, we describe a fractionation process of moringa leaves by fast centrifugal partition chromatography (FCPC) to generate polyphenol and isothiocyanate (ITC) rich fractions (Fig. 1). The polyphenol-rich fraction showed direct antioxidant activity assayed by oxygen radical absorbance capacity (ORAC), while the ITC-rich fraction demonstrated indirect antioxidant properties assayed by NQO1 activity in Hepa1c1c7 cells. Also, purified 4-[(α-l-rhamnosyloxy) benzyl] isothiocyanate (ITC-1), and 4-[(4'-O-acetyl-α-l-rhamnosyloxy)benzyl] isothio-cyanate (ITC-4) were evaluated for their ORAC and NQO1 inducer potency in comparison with sulforaphane (SF) at 5µM (Fig. 2). Both ITCs were as potent as SF in inducing NQO1 activity. These findings suggest that edible M. oleifera leaves contain a potent mixture of antioxidants that could explain its health promoting effects.