## 3 Results and Discussion
This group includes flavonoids, flavones, isoflavones, flavanones, flavononols, anthocyanin and tannins [45]. Flavonoids have a number of medicinal benefits, including anticancer, antioxidant, anti-inflammatory, and antiviral properties [54]. Their regular consumption is associated with a diminished risk of some chronic diseases, including cancer, cardiovascular disease and neurodegenerative disorders [55]. The TPC of methanolic extracts (g CE/kg) corresponds to TPC (g GAE/kg) and the highest concentrations (mean \(\pm\) SD) were found in _S. dimorphus_ (6.68 \(\pm\) 0.32), followed in descending order by _A. calamus_ (3.42 \(\pm\) 0.26), _L. minuta_ (3.02 \(\pm\) 0.24) and _C. vulgaris_ (2.29 \(\pm\) 0.19) (Figure 1). Figure 1: Total phenolic content (g GAE/kg), total flavonoid content (g CE/kg) and radical scavenging potential (mmol TE/kg) of methanolic extracts from different plants. The TFC of _A. calamus_ (3.42 g CE/kg) was lower than the results of [PERSON] and [PERSON] [53] (11.1 g CE/kg) and especially of [PERSON] and [PERSON] [11] (74.11 g CE/kg). Both authors used methanol as an extractant [11; 53]. One of the possible explanations for the substantial discrepancies of the experimental data are the findings of [PERSON] et al. [52], who reported some great differences between the TFC of methanolic extracts of _A. calamus_ harvested from 20 ecological niches in India. The various sample values ranged from 0.5 g CE/kg to 24.5 g CE/kg, which further emphasizes the role of geographic and climatic conditions in the antioxidant potential of different plants. After statistical data processing, the authors concluded that altitudes are positively associated with TFC in plants [52]. It should be noted that all aforementioned authors applied different methods for extract preparation--[PERSON] and [PERSON] [11] performed extraction at 60 \({}^{\circ}\)C in a horizontal water bath shaker, whereas [PERSON] et al. [52] used the Soxhlet method and [PERSON] and [PERSON] [53] utilized maceration, which further increased the differences in the yield of total flavonoids. The lack of literature data or major methodological differences prevents the comparison of TFC of _S. dimorphus_, _L. minuta_ and _C. vulgaris_ methanolic extracts. There are many different antioxidants presented in plants. Therefore it is very difficult to measure each antioxidant component separately. A DPPH assay tests the ability of a substance to quench a DPPH radical through the donation of an electron [56]. In this way, DPPH radicals are widely used as a model system to evaluate the scavenging activities of natural antioxidant compounds [57]. The radical scavenging potentials of _S. dimorphus_, _L. minuta_, _A. calamus_ and _C. vulgaris_ corresponded to TPC and TFC and were 106 \(\pm\) 10 mmol TE/kg (26.86 \(\pm\) 1.94%), 94 \(\pm\) 9 mmol TE/kg (25.17 \(\pm\) 1.93%), 90 \(\pm\) 9 mmol TE/kg (24.56 \(\pm\) 1.87%), 53 \(\pm\) 5 mmol TE/kg (19.5 \(\pm\) 1.75%), respectively (mean \(\pm\) SD, Figure 1). The DPPH of _S. dimorphus_ methanolic extracts (26.86%) corresponds to the DPPH of ethanol/water extracts of _Scenedesmus_ sp.--25.65% [26]. [PERSON] et al. [26] reported the highest radical scavenging effect from ethyl acetate solvent (52.02%), followed by ethanol/water (25.65%), hexane (12.99%) and water (8.40%). These experimental results showed the impact of extractant type on radical scavenging activity. As mentioned above, [PERSON] et al. [26] used ultrasonication as a method of extract preparation. The DPPH of _C. vulgaris_ extracts (19.5%) is lower than the radical scavenging activity obtained by [PERSON] et al. [17] (35.81-37.67%) and [PERSON] et al. [47] (39.4%), but is higher than the results of [PERSON] et al. [48] (16.87%). All of the aforementioned authors used methanol as a solvent [17; 47; 48]. It is important to emphasize that methanolic extracts of _C. vulgaris_ tested by [PERSON] et al.