Total phenolics and flavonoids of mulberry and BE were investigated spectrophotometrically as previously described[22]. In brief, different concentrations of
mulberry or BE were mixed with 0.2 M Folin–Ciocalteau reagent, and the reaction was
neutralized by adding 7.5% (w/v) sodium carbonate. The absorbance of the resulting
blue color product was measured at 765 nm spectrophotometrically. Gallic acid was
used as a standard, and total phenolic content was expressed as gallic acid equivalents
per gram of extracts. To evaluate flavonoid content of mulberry and BE, different
concentrations of extracts or standard (rutin) were mixed with 5% (v/v) NaNO2,10%
AlCl3and 1 M NaOH. After mixing well, the absorbance was read at 510 nm and flavonoid
contents were expressed as milligram of rutin equivalents per gram of extracts.
The total antioxidant capacity of mulberry and BE were measured using trolox
equivalent antioxidant capacity (TEAC) assay previously described[23]. To measure
antioxidant capacity, different concentrations of ME or BE were mixed well with greenblue 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS
●+
radical), which
was generated by the mix of peroxidase (4.4 U/ml), ABTS (100μM) and H2O2(50μM).
Absorbance was monitored at 734 nm after 10 min incubation in the dark. TEAC value is
expressed as millimolar concentration of trolox equivalence