Antioxidant role of morusin and mulberrofuran B in ethanol extract of Morus alba roots.

The white mulberry, Morus alba, is distributed worldwide and known for its antioxidant properties. Ethanol extract of six varieties of M. alba roots were studied (IZ 13/6, IZ 40, IZ 56/4, IZ 64, Indonesia and Tigreada). From variety IZ 40, two secondary metabolites were isolated and unambiguously identified by 2 D NMR experiments as morusin and mulberrofuran B. These were quantified in the varieties by liquid chromatography, recording 5.27-16.74% for the first, and 0.54-3.55% for the latter. Mulberrofuran B presented higher activity than morusin by phosphomolybdenum (1531.33 ± 20.28 mmol ascorbic acid/g) and ferrocyanide (14.39%) methods, ABTS (95.74 ± 4.21 µM) and DPPH (843.87 ± 10.65 µM) radical sequestration capacity, while morusin showed significant statistical correlation with antioxidant activity for some M. alba varieties. These results suggested that morusin influences antioxidant activity of M. alba in synergism with other compounds and can be a good chemical marker in this species.