## 3 Results and Discussion
### Phenolic Compounds
#### 3.2.1 Oregano  
Rosmarinic acid was the major phenolic compound found in all oregano extracts (Table 5), ranging between 1.67 mg/g DW for BPGV1042 and 3.44 mg/g DW for BPGV16272. Rosmarinic acid is an ester of caffeic acid with various biological activities demonstrated, such as anti-inflammatory, antioxidant, antiviral, antibacterial, and antitumoral activities [35,36]. Other phenolic acids were found in oregano, including gentisic acid (between 0.121 and 0.576 mg/g DW) and 4-hydroxybenzoic acid (between 0.0272 and 0.0747 mg/g DW), making this class of phenolic compound the major class in oregano extracts. The chromatograms of the major phenolic compounds found in oregano are shown in Figure 2.  
Similar amounts of rosmarinic acid were reported by [PERSON] et al. [23] (0.66-1.65 mg/g DW) in samples collected in Iran; however, a high concentration of rosmarinic acid was reported by [PERSON] et al. [24] (18.69 mg/g DW), who evaluated 174 samples of _O. vulgare_ from different origins (including Germany, Georgia, Italy, Albania, Spain, the Czech Republic, the USA, and Hungary). Contrary to our results, [PERSON] et al. [37] reported that thymol was the major phenolic compound in oregano available in Portuguese markets, with 1.76 mg/g DW, followed by rosmarinic acid (0.207 mg/g DW) and carvacrol (0.117 mg/g DW). These differences in the individual phenolic content may also be related to the extraction method, for example, the rosmarinic acid content of the same oregano sample with microwave-assisted extraction (MAE) was 1.5 times higher when compared to conventional extraction [10]. Similarly, our analysis was limited by the lack of high purity standards for thymol and carvacrol, emphasizing the variability of phenolic profiles depending on the analytical methods and standards available.  
No statistical difference was found in the content of kaempfer-3-O-B-rutinoside. The content of this flavonoid ranged between 0.0088 and 0.0156 mg/g DW. This is contrary to [PERSON] et al. [23] who found a large disparity in the kaempfer content, ranging between 0.005 and 0.898 mg/g DW.  
Flavanones were one of the major groups of flavonoids present in oregano extracts, including naringenin, eriodyctiol, and sakuranetin, with higher levels in samples collected in Portalegre (\(p<0.05\)), while the samples collected in Braganca showed a lower content of those compounds. This class is typical of citrus fruits, but was previously detected by [PERSON] et al. [23] with higher levels (0.103 to 0.188 mg/g DW) in oregano collected in Iran.  
Other minor compounds were found in oregano extracts, including genistin (4.88 g/g DW), luteolin (3.60 g/g DW), and apigenin (1.93 g/g DW). Those flavones were also found in oregano from Iran [23], although in higher amounts; for example, 2.99 mg of luteolin and 0.022 mg of apigenin per gram of dried _O. vulgare_.  
Furthermore, (-)-gallocatechin gallate was found in oregano extracts, between 0.0044 and 0.0062 mg/g DW, with higher levels for BPGV16286 and BPGV16427, with significant superiority (\(p>0.05\)). This compound is a non-epimerized isomer of a catechin derivative (epigallocatechin gallate), characteristically of green tea, and is responsible for their antioxidant capacity and biological activities [38].