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Direct and Indirect Antioxidant Activity of Polyphenol- and Isothiocyanate-Enriched Fractions from Moringa oleifera
journal contribution
posted on 2015-02-11, 00:00 authored by Tugba Boyunegmez Tumer, Patricio Rojas-Silva, Alexander Poulev, Ilya Raskin, Carrie WatermanMoringa oleifera Lam. is a fast-growing,
tropical tree with various edible parts used as nutritious food and
traditional medicine. This study describes an efficient preparatory
strategy to extract and fractionate moringa leaves by fast centrifugal
partition chromatography (FCPC) to produce polyphenol and isothiocyanate
(ITC) rich fractions. Characterization and further purification of
these fractions showed that moringa polyphenols were potent direct
antioxidants assayed by oxygen radical absorbance capacity (ORAC),
whereas moringa ITCs were effective indirect antioxidants assayed
by induction of NAD(P)H quinone oxidoreductase 1 (NQO1) activity in
Hepa1c1c7 cells. In addition, purified 4-[(α-l-rhamnosyloxy)benzyl]isothiocyanate
and 4-[(4′-O-acetyl-α-l-rhamnosyloxy)benzyl]isothiocyanate
were further evaluated for their ORAC and NQO1 inducer potency in
comparison with sulforaphane (SF). Both ITCs were as potent as SF
in inducing NQO1 activity. These findings suggest that moringa leaves
contain a potent mixture of direct and indirect antioxidants that
can explain its various health-promoting effects.