## 3 Results and Discussion
### Total Polyphenol, Flavonoid and Phenolic Acid Content
Based on the obtained results, the tested samples can be listed in the following order: _Primula_ veris L. > _Thimus serpyellum_ L. > _Fragaria_ _resca_ L. > _Potentilla anserina_ L. > _Melissa officinalis_ L. > _Salvia officinalis_ L. > _Plantago lanccolata_ L. > _Tropaeolum majus_ L. > _Mentha piperta_ L. > _Calendula officinalis_ L. > _Matricaria chamomilla_ L. > _Equisetum aervense_ L. > _Urtica dioica_ L. > _Achillea millefolium_ L. > _Ribes nigrum_ L. > _Rosa canina_ L. (Table 2). The highest content of flavonoids of 48.35 \(\pm\)3.77 mg QE/g was determined in _Primula veris_ L. The second highest content was determined in _Thimus serpyellum_ L.--40.89 \(\pm\) 0.94 mg QE/g and third was _Fragaria vesca_ L.--39.05 \(\pm\) 0.27 mg QE/g. [PERSON] et al. [38] determined total flavonoids in the amount of 15.31 \(\pm\) 7.61 mg QE/100 g in a 10% ethanol extract of _Primula_ flowers and 17.65 \(\pm\) 8.72 mg QE/100 g in a 20% extract. The results of their work suggest that _Primula_ extracts may play a significant role in reducing oxidative stress but more detailed analyses are still necessary. [PERSON] et al. [39] reported that, in _Mellisa_, quercetin (0.15 mg/g) and rutin (1.46 mg/g) are dominant flavonoids. In study of Hamad [40] it was determined that quercetin and kaempferol glycosides are present in the _Calendula_ flower, while myricetin glycosides are absent. The flowers in Hamad study were extracted with ethanol 70% [40]. Flavonoids occur as aglycones, glycosides and methylated derivatives. The basic structure of flavonoids is an aglycone. The bioavailability, metabolism, and biological activity of flavonoids depend on the configuration, the total number of hydroxyl groups, and the ability of the functional groups to replace their nuclear structure. It has been proven that many flavonoids exhibit antioxidant activity and free radical scavenging capacity, decrease the risk of coronary heart disease, and induce hepatotoxicity, anti-inflammatory and anticancer effects, while others exhibit potential antiviral effects [36]. [PERSON] et al. [41] analyzed the flowers of three _Primula_ species. The results showed a wide spectrum of flavonoids and their glycosylated and methylated derivatives, such as: (+)-catechin, kaempferol-3-O-galactoside-rhannoside-7-O-rhannoside, kaempferol-3-O-rutinoside, quercetin-3-O-rutinoside, and primulic acid. _Primula_ is one of the most important medicinal plants that has been used in the treatment of gout and headaches since the Middle Ages. Triterpenoid saponins from roots and flowers can treat bronchitis and colds by improving the dissolution of mucus and experoration. The total content of phenolic acids was in the range of 5.49 \(\pm\) 0.56 mg CAE/g to 102.31 \(\pm\) 2.89 mg CAE/g. Based on the obtained results, the tested samples can be listed in the following order: _Thimus serpyellum_ L. > _Menthala piperta_ L. > _Melissa officinalis_ L. > _Plantago lanccolata_ L. > _Rosa canina_ L. > _Fragaria vesca_ L. > _Salvia officinalis_ L. > _Primula veris_ L. > _Ribes nigrum_ L. > _Urtica dioica_ L. > _Achillea millefolium_ L. > _Tropaeolum majus_ L. > _Equisetum aervense_ L. > _Potentilla anserina_ L. > _Matricaria chamomilla_ L. > _Calendula officinalis_ L. (Table 2). Phenolic acids are aromatic secondary plant metabolites widespread throughout the plant kingdom. In general, the name \"phenolic acids\" describes phenols that have a single functional carboxyl group, but when describing plant metabolites it refers to a different group of organic acids. Phenolic acids are derivatives of benzoic and cinnamic acids. These acids exhibit high antioxidant activity in vitro and thus are beneficial for human health. Because they are contained in all plant foods, people consume them daily. The estimated daily intake is 25 mg-1 g, depending on the diet. Caffeic acid, one of the most important naturally occurring acids, is known for selectively blocking the biosynthesis of leukotrienes(components involved in immunoregulatory diseases, asthma and allergic reactions).