2.2. Sample preparation
Extractions of PSPAs were performed as previously described (Li et al., 2013), with some modifications. Briefly, each sample of PSP powder (50.0 g) was centrifuged for 15 min (4000 rpm, 3500g, 4 °C) after extraction with 1.0 L 50% aqueous ethanol containing 0.05% hydrochloric acid for 24 h at 4 °C in the dark. The supernatant was concentrated by evaporation under vacuum at 40 °C and the concentrated extract was applied to a macroporous resin AB-8 column that had been pre-equilibrated with water containing 1% formic acid. The column was then equilibrated with three column volumes (3 CV) of the equilibrium liquid to remove sugars and proteins. PSPAs were then eluted with 3 CV 70% aqueous ethanol containing 1% formic acid; the eluent was concentrated under vacuum (40 °C) to remove the ethanol from the solution. The concentrate was partitioned with ethyl acetate (200 mL × 3) to remove other phenols ( Oki et al., 2002). The aqueous fraction was then lyophilised (−40 °C) to obtain a dry powder, 10% of which was weighed and dissolved in 100 mL water prior to total anthocyanin content (TAC) analysis, while the remaining powder was stored at −20 °C for use in the other experiments.
2.2. Sample preparationExtractions of PSPAs were performed as previously described (Li et al., 2013), with some modifications. Briefly, each sample of PSP powder (50.0 g) was centrifuged for 15 min (4000 rpm, 3500g, 4 °C) after extraction with 1.0 L 50% aqueous ethanol containing 0.05% hydrochloric acid for 24 h at 4 °C in the dark. The supernatant was concentrated by evaporation under vacuum at 40 °C and the concentrated extract was applied to a macroporous resin AB-8 column that had been pre-equilibrated with water containing 1% formic acid. The column was then equilibrated with three column volumes (3 CV) of the equilibrium liquid to remove sugars and proteins. PSPAs were then eluted with 3 CV 70% aqueous ethanol containing 1% formic acid; the eluent was concentrated under vacuum (40 °C) to remove the ethanol from the solution. The concentrate was partitioned with ethyl acetate (200 mL × 3) to remove other phenols ( Oki et al., 2002). The aqueous fraction was then lyophilised (−40 °C) to obtain a dry powder, 10% of which was weighed and dissolved in 100 mL water prior to total anthocyanin content (TAC) analysis, while the remaining powder was stored at −20 °C for use in the other experiments.
การแปล กรุณารอสักครู่..
