Antioxidant activities and phenolic composition of safflower (Carthamus tinctorius L.) plant during their growth cycle

The aim of this study was to determine the total polyphenol content in the aerial part of safflower (Carthamus tinctorius L.), during its growth cycle from the late vegetative to early flowering stages, in order to identify the richest growth stage, in terms of antioxidants, and therefore the most potentially favourable, in an attempt to contribute to the use of this plant's extracts as alternative antioxidants. Samples were extracted with methanol, and evaluated for their radical scavenging activities against ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC). The total phenolic compound (TPC) was determined using Folin-Ciocalteu's phenol reagent on extracts from ground samples, with an 80:20 (v/v) methanol:water at a solid-to-solvent ratio of 1:10 (w/v). All the chemical determinations were performed in triplicate. Data were analyzed by means of one-way analysis of variance (ANOVA). The TPC content of the extracts ranged from 48.6 to 71.1 mg Catechin eq./g extract. The TEAC content ranged from 0.275 to 0.334 mmol Trolox eq./ g extract, while the FRAP content ranged from 0.730 to 1.108 mmol Fe2+/g extract. The profile of the phenolic compounds, determined by means of a DAD-HPLC system, was characterized by the presence of six compounds. On the basis of UV-DAD spectra, these compounds were described as caffeic acid, quercetin and luteoin-7-O-glucoside derivatives.