## 3 Results and Discussion  
### Antioxidant Properties, Bioactive Content and Iron (II) Chelating Activity  
Polyphenols, which are plant-derived natural molecules found as secondary metabolites, present important biological activities, with their antioxidant capacity one of the most important properties for physiological function. The total polyphenols and flavonoid content, as well as the antioxidant effects, were studied in saffron and its floral by-products extracts. The results of the antioxidant activity and bioactive content are shown in Table 1. Saffron floral by-products and saffron stigmas presented a high concentration of total polyphenols, between 32-36 mg GAE/g dw, except for Spanish saffron, which had a significant highest amount (44.80 \(\pm\) 2.30 mg GAE/g dw). Regarding the total flavonoid content, saffron stigmas from Spain, Iran, and Greece showed high levels of flavonoids in the range of 15-18 mg CE/g dw. However, saffron flowers had a lower concentration of total flavonoids (4-5 mg CE/g dw) than saffron stigmas. These results obtained for saffron flowers were in accordance with the ones described by [PERSON] et al. (2019), reporting values about 30 mg/g for TPC and values lower than 10 mg/g for TPC in saffron tepal methanol extracts from China. Moreover, the values obtained for saffron stigmas were higher than those reported in the study of [PERSON] et al. (2019), in which saffron stigmas methanol extracts from Iran presented 6.5 \(\pm\) 0.02 mg GAE/g dw for TPC and 5.8 \(\pm\) 0.12 mg ruin equivalents/g dw for TPC. Within the group of flavonoids, anthocyanins are one class of pigments that also present antioxidant properties (20). Saffron flowers without stigmas, SFL1 and SFL2, contained high levels of anthocyanins, showing SFL2 a significantly higher concentration than SFL1. [PERSON] et al. (2017) also found the highest anthocyanin content in saffron petals from Spain and were also detected in whole flowers and floral bio-residues. Regarding carotenoids, they are organic pigments from the group of isoprenoids that are found naturally in plants and exert several beneficial functions in the body due to their antioxidant properties, among others. Based on their structures, carotenes are one of the main subclasses of carotenoids, with \(\beta\)-carotene and \(\alpha\)-carotene the two major types. Beta-carotene was found to be the precursor of crocins. Crocins, which are glycosyl esters of crocetin, are the main chemical components of saffron, responsible for many of its pharmacological and biomedical properties. The synthesis of these apocarotonoids involves several reactions, including the cleavage of beta-carotene and zexaanthin, oxidation and glycosylation steps (20). Saffron stigmas showed a high proportion of total beta-carotene being higher than 70%. Greek saffron presented the highest concentration (90.82 \(\pm\) 8.37%) and Iranian saffron the lowest, having 20% less total beta-carotene than Greek saffron (71.06 \(\pm\) 6.47%) (Table 1). With respect to the crocetin esters content, the _trans_ isomers, which are the majority, were studied. _Trans_-4-GG crocin was found in higher concentrations than _trans_-3-GG-crocin in all saffron samples. Spanish stigmas presented the significant highest proportion of total crocins (17.04 \(\pm\) 0.18%) and of _trans_-4-GG crocin (11.91 \(\pm\) 0.13%) (Table 2). The same tendency for beta-carotene content was shown by Iranian stigmas, having the lowest proportion of total crocins (13.19 \(\pm\) 0.78%) and of _trans_-4-GG crocin (9.22 \(\pm\) 0.30%) (Table 2).