Abstract:

The present study aims at evaluating the antioxidant and antiglycation activities of mulberry extracts rich in
phenolics and the relationships between phenolic components and their activities. Mulberry fruit (Morus atropurpurea
Roxb.) extract was separated by Sephadex LH-20 gel filtration column chromatography into six fractions (F1, F2, F3, F4, F5
and F6). Total phenolics and total anthocyanins of different fractions and their main phenolic components were quantified by
Folin-Ciocalteu method, pH differential method and high performance liquid chromatography (HPLC). DPPH and ABTS+
radical scavenging and ferric reducing assays were conducted to evaluate the antioxidant abilities of fractions. Bovine
serum albumin (BSA)-fructose and BSA-methyglyoxal (MGO) models were applied for the measurement of antiglycation
capacity. The results indicated that the extracts contained mainly five phenolic acids (gallic acid, hydroxybenzoic acid,
caffeic acid, p-coumaric acid and o-coumaric acid), two anthocyanins (cyanidin-3-glucoside and cyanidin-3-rutinoside)
and two flavonoids (rutin and quercetin). Fraction F3 contained the highest amount of anthocyanin ((101.10 ± 2.39) mg
cyanidin-3-glucoside/g md, P < 0.05) and F5 was the richest in total phenolic compounds ((188.05 ± 2.01) mg gallic acid
equivalent/g md, P < 0.05). F3 had the highest antioxidant capacity among fractions (P < 0.05, which showed DPPH
and ABTS+ radical scavenging activity of (129.33 ± 5.58) and (194.33 ± 2.48) mmol/g and ferric reducing power of
(130.44 ± 1.38) mmol/g, respectively) while the antiglycation capacity of F5 was the highest (P < 0.05), with percentage
inhibition of (87.23 ± 0.36)% and (66.99 ± 1.62)% in BSA-fructose and BSA-MGO model, respectively. The linear
regression analysis showed that the antioxidant capacity of the extracts was due mostly to anthocyanins and their
antiglycation activity was attributed to total phenolic compounds.

Key words: mulberry, phenolic compound, antioxidant, antiglycation