High pressure liquid chromatography – cupric ion reducing antioxidant capacity assay on Goldenrod (Solidago L.) type plants

The aim of the study: to optimise HPLC- cupric reducing antioxidant capacity (CUPRAC) assay with post-column detectionand evaluate antioxidant activity in leaves and flowers of Solidago L. type plants. Materials and methods: leaves and flowers of Solidago canadensis L., Solidago gigantean Ait. and Solidago virgaurea L. were collected in different places of Lithuania and dried at 25 °C. 0.1 g of air-dried S. canadensis, S. gigantea and S. virgaurea leafs and flowers were extracted with 10 mL of methanol water mixture (70:30 v/v) by ultra-sonication at 25 °C for 50 min. The prepared extracts were passed through a 0.22 µm filter. Chromatographic fractionation of active agents was carried out with 150x4,6 mm, 3 µm YMC column (injection volume – 10 µL, elution flow rate – 1.0 mL/min). The mobile phase of gradient elution system consisted of 0.05% aqueous trifluoroacetic acid and acetonitrile, the flow rate of CUPRAC solution – 0,4 ml/min. Results: the best results of Solidago L. herbal extracts’ antioxidant activity were achieved while using 10 m length PEEK coil (OD 1.58 mm, ID 0.25 mm) with 50oC temperature maintained (the flow rate of CUPRAC solution was 0.4 ml/min, absorption was measured at 450 nm). Antioxidant activity was expressed as Trolox equivalent (TEAC). The strongest antioxidant properties were shownby leaves and flowers of S.gigantea Ait. The largest TEAC of chlorogenic acid (253,19 ± 123,71µmol/g) and quercitrin (334,89 ± 180,55 µmol/g)were observed in leaves of S. gigantea Ait. The total antioxidant reducing activity of tested compounds in flowers and leaves of Solidago L. was evaluated as well. The strongest antioxidant properties were shown in leaves (660,11 ± 279,36µmol/g) and flowers (327,35 ± 104,03µmol/g) of S.gigantea Ait.The statistical significance of the data was evaluated. This research was funded by Lithuanian Science Council(No. MIP-50/2013)