## 3 Results and Discussion
### Polyphenolic Composition and Antioxidant Activity  
Aside from the total polyphenol yield, the polyphenolic profile of the extracts obtained with 1- and 2-propanol was also of importance, and, thus, the extracts generated under optimized conditions were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) to tentatively identify and quantify the principal constituents. The analyses revealed that the principal compounds were chlorogenic acid, accompanied by caffe acid and _p_-coumaric acid (see Supplementary Material). Chlorogenic acid was characterized by its molecular ion at \(m/z=353\), and the diagnostic fragments at \(m/z=191.1\) and 85.2. Likewise, caffeic acid was identified by the molecular ion at \(m/z=179\) and the diagnostic fragment at \(m/z=135.1\), and _p_-coumaric acid by the corresponding ions at \(m/z=163\) and 119.3. The treatment with 1-propanol/sulfuric acid and 2-propanol/sulfuric acid resulted in virtually equal caffeic acid recovery, but the former treatment afforded 50% higher chlorogenic acid recovery. Both extracts also contained minor amounts of _p_-coumaric acid, which, in the case of 2-propanol/sulfuric acid treatment, accounted for no more than 1.2% of the total hydroxycinnamates considered (Table 4). In total, the extract produced with the 1-propanol/sulfuric acid was 30% richer in hydroxycinnamates. The predominance of chlorogenic acid in PP extracts has been previously described by other authors, reporting yields of 250.15 [19], 267.40 [33], and 904.21 ug g\({}^{-1}\) DM [34]. However, yields as low as 83.67 ug g\({}^{-1}\) DM [26] and as high as 4100 ug g\({}^{-1}\) DM [29] have also been found. On the other hand, caffeic acid has been shown to accompany chlorogenic acid at significantly lower levels, ranging usually from 89 to 920 ug g\({}^{-1}\) DM, although its content may reach up to 1297 ug g\({}^{-1}\) DM [35]. Both extracts were also tested for antioxidant activity by determining the ferric-reducing power (P\({}_{\text{R}}\)) and the antiradical activity (A\({}_{\text{AR}}\)). With reference to A\({}_{\text{AR}}\), the extract obtained with 2-propanol/sulfuric acid treatment displayed 29% higher value compared to the extract produced with 1-propanol/sulfuric acid. Conversely, the 1-propanol/sulfuric acid treatment afforded extract with 20% higher P\({}_{\text{R}}\) compared to the control extract obtained using with 2-propanol/sulfuric acid (Table 4). These discrepancies revealed a diversified response of the extracts to the A\({}_{\text{AR}}\) and P\({}_{\text{R}}\) tests. Such a disagreement of the results from the two antioxidants tests would not come as a surprise, given that the antioxidant responses of mixtures of antioxidant compounds may depend on several factors, such as the relevant proportion of each compound in the mixture tested. Evidence arising from the examination of the radical-scavenging activity of polyphenolic mixtures indicated the manifestation of antagonistic and/or synergistic effects, which depended on the nature of polyphenols in the mixture [36]. The study of several binary antioxidant mixtures at varying proportions with cyclic voltammetry and a chemiluminescence-based test confirmed such behavior, demonstrating again the expression of either antagonism or synergism, depending on the nature of the antioxidants interacting and their relative ratio [37; 38].