## 3 Results and Discussion
The obtained results are consistent with [PERSON] et al. [43], who found that 51% acetone has the highest recovery efficiency of phenolic compounds (12.20 mg GAE/g DM) from orange peel. The obtained results can also be compared with the research conducted by [PERSON] and [PERSON] [44], in which one of the most effective solvents used in extraction turned out to be mixtures of water and acetone (84.9 mg GAE/g DM) and water and methanol (85.4 mg GAE/g DM). [PERSON] et al. [45] showed that the optimal condition for the ultrasound-assisted extraction (UAE) of TPC from rose fruits (_Rosa rugosa_) was 50% ethanol for 30 min. at 50 \({}^{\circ}\)C. The content of TPC in the extract (at 50 \({}^{\circ}\)C after 30 min) was 95.69 mg TPC/g dry weight. [PERSON] et al. [9] reported that four extracts from the pseudofruit pomace of _Rosa rugosa_ Thunb. differed in their total content of polyphenols. The content of polyphenols in 60% acetone extracts was higher than in 60% ethanol extracts and amounted to 14.9 g/100 g DM for water-acetone extract crude, 33.2 g/100 g DM for water-acetone extract purified, 8.8 g/100 g DM for water-ethanol extract crude, and 29.2 g/100 g DM for water-acetone extract purified. [PERSON] et al. [46] determined TPC in 80% methanol extract as 29.20 mg GAE/g of dried rosehip pomace. Similarly, according to [PERSON] et al. [47], the best TPC (59.69 mg GAE/g DM) in three different brands of rose hip tea (_Rosa canina_ L) was obtained using a 50% MeOH mixture. However, according to [PERSON] et al. [48], the most effective solvent for recovering TPC from lemon pomace was absolute methanol and 50% acetone. Methanol was also the most effective solvent for the extraction of hesperidin, which is a flavonoid compound (flavanone) [49]. According to the report by [PERSON] et al. [50], the most effective solvent for the extraction of TPC from calamondin (_Citrus mitis_ Blanco) was hot water compared to absolute methanol, ethanol, or their combination with water. [PERSON] et al. [51] found that ethanol had the highest efficiency of TPC extraction from pompegranate. Research conducted by [PERSON] et al. [52] on rose petals (_Rosa rugosa_) showed that one of the best solvents for the extraction of polyphenic compounds is a 40% ethanol solution. [PERSON] et al. [15] reported that the total phenolic content in _Rosa rugosa_ samples ranged from 0.14 to 13.9 mg GAE/mL of rose extract (infusion or tincture). Infusions were obtained by pouring 2 g of plant material with 100 mL of boiling water, and tinctures were obtained by extracting 10 g of powdered plant material with 50 g of 70\({}^{\circ}\) ethanol. Researchers determined the highest phenol content in tinctures of _Rosa rugosa_ flowers, leaves, and roots (12.75-13.9 mg/mL) and the lowest in the infusion of _Rosa rugosa_ nuts (0.14 mg/mL). The total phenolic content in _Rosa rugosa_ pseudofruit tinctures was 11.88 mg GAE/mL. Similar results were obtained by other researchers, who showed that the content of polyphenols in methanolic rose (_Rosa nutkana_ and _Rosa woodisi_) extracts depends on the part of the plant used [21]. The concentration of polyphenols in methanolic extracts from rose fruits, _Rosa nutkana_, and _Rosa woodisi_, was higher than in nut extracts. The literature results are similar to our research, which showed that extraction solvents significantly affect the recovery efficiency of TPC from plant materials. The data showed that the TPC recovery for individual solvents was different and resulted from different solvent polarities, different polyphenol structures, and the type of plant raw material. According to [PERSON] and [PERSON] [53], for example, flavonoid glycosides and more polar aglycones can be extracted with alcohols or mixtures of alcohols and water, while low-polarity solvents such as acetone are suitable for the extraction of less polar flavonoids such as isoflav, flavanones, and methylated flavones.