## 3 Results and Discussion  
### Antioxidant Activity  
The antioxidant activity determined in medicinal plants using the DPPH method ranged from 3.16 \(\pm\) 0.51 mg TE/g to 29.43 \(\pm\) 0.10 mg TE/g. All the samples demonstrated the ability to inhibit DPPH radicals and be ranked in the following order based on the results of this measurement: _Rosa canina_ L. > _Urtica dioica_ L. > _Fragaria vesca_ L. > _Equisitum arvense_ L. > _Ribes nigrum_ L. > _Tropeaolum majus_ L. > _Potentilla anserina_ L. > _Matricaria chamonilla_ L. > _Mentha piperita_ L. > _Primula veris_ L. > _Achillea millefolium_ L. > _Melissa officinalis_ L. > _Plan-tago lanccolata_ L. > _Thumus serpylum_ L. > _Salvia officinalis_ L. > _Calendula officinalis_ L. > _Calendula officinalis_ L. (Table 1). [PERSON] et al. [24], analyzed the antioxidant activity of rosehip fruit extracts (_Rosa canina_ L.) obtained using three different methods (distilled water, 50% ethanol, 70% ethanol), and found the following values: 211.5 \(\pm\) 5.5 mM TE/g (distilled water), 295.0 \(\pm\) 1.0 mM TE/g (50% ethanol) and 286.4 \(\pm\) 2.9 mM TE/g (70% ethanol). [PERSON] et al. [25] also confirmed the high antioxidant activity of _R. canina_. It is known that the fruits of rosehip have the highest content of vitamin C (30-1300 mg/g) among fruits and vegetables. In addition, rosehip also contains other vitamins, mineral compounds, carotenoids, tocopherols, flavonoids, organicacids, tannins, pectin, sugars, amino acids, and essential oils, which are all responsible for antioxidant activity [26]. The antioxidant activity of an aqueous extract from nettle (_Urtica dioica_ L.) measured with the DPPH method by [PERSON] et al. [27] was reported as (IC\({}_{50}\)) 159.88 \(\pm\) 1.57 ug/mL. These authors also noted that nettle leaves are rich in antioxidant compounds like chlorophylls, vitamins, mineral compounds, and polyphenols. Medicinal plants can be used as natural preservatives in the food industry, and have been used since ancient times for shelf-life prolongation and to improve sensory properties. In a study by [PERSON] et al. [28], hydroalcoholic and water extracts of nettle extended the shelf life of minced kilka from 2 to 8 days. Based on the reducing power (determined using the phosphomolybdenum method), it is possible to rank the tested medicinal plants in the following order: _Fragaria vesca_ L. > _Plantago lanccolata_ L. > _Rosa canina_ L. > _Thymus serpyllum_ L. > _Melissa officinalis_ L. > _Ribes nigerum_ L. > _Salvia officinalis_ L. > _Mentha pipertia_ L. > _Primuda veris_ L. > _Propacoulum analyus_ L. > _Matricia chamoulin_ L. > _Potentilla anserina_ L. > _Achillea millefolium_ L. > _Urtica dioica_ L. > _Calendula officinalis_ L. > _Equisetum arrense_ L. (Table 1). The results ranged from 171.64 \(\pm\) 13.25 mg TE/g to 679.56 \(\pm\) 3.06 mg TE/g. The observed discrepancies between the parameters reflecting antioxidant activity obtained using both methods are mainly a result of methodological differences. As each method is based on a different principle, each captures a different range of biologically active substances. DPPH' is a stable free radical, with a dark purple color and strong absorbance around 515 nm. Antioxidant compounds contained in the medium convert the DPPH' radical to a more stable DPPH' molecular product by donating an electron or a hydrogen atom. The resulting change in the color of the reaction solution from dark purple to pale yellow enables spectrophotometric determination of the antioxidant activity [29]. In the phosphomolybdenum method, the reducing power is generally associated with the presence of reductones (mainly polyphenols), which act by their antioxidant effect in a way such that they break the free radical chain by providing a hydrogen atom [30]. The reducing capacity of compounds can serve as an important indicator of their potential antioxidant activity [31].