## 3 Results and Discussion
### Content of TPC Using the Folin-Ciocalteu Reagent Method
#### Extracts Obtained with Ultrasound-Assisted Extraction (UAE)  
Based on the results obtained for individual extracts, differing in the type of solvent used and the cultivars of apple leaves, a chart was prepared showing the content of total polyphenols in these extracts, expressed in mg GAE/1 g of DW (Figure 1).  
The one-way analysis of variance showed that the apple leaf cultivar had no significant effect on the content of total polyphenols in extracts prepared using the UAE method. However, the type of solvent used significantly influenced the content of polyphenols in the extracts. Water-alcoholic extracts had a significantly higher content of total phenolic compounds than water extracts.  
Figure 1: Content of total polyphenols in apple leaf extracts obtained with ultrasound-assisted extraction.  
The two-way analysis of variance showed that the water-methanol and water-ethanol extracts from the leaves of the Ligol cultivar were characterised by the significantly highest polyphenol content of all extracts prepared with ultrasound-assisted extraction and contained, respectively, 75 and 73.3 mg GAE/1 g of DW. The water-methanol extract from the leaves of the Gloster cultivar contained significantly more polyphenols (60.8 mg GAE/1 g of DW) than other water and water-ethanol extracts, but it did not differ significantly in terms of the content of total phenolic compounds from the water-methanol extract from the leaves of the Gala cultivar (58.8 mg GAE/1 g of DW). The latter did not differ significantly from its water-ethanol counterpart (54.8 mg GAE/1 g of DW). However, the water-ethanol extract from the leaves of the Gala cultivar did not differ statistically in the content of polyphenols from the same type of extract made from the leaves of the Gloster cultivar (53.2 mg GAE/1 g of DW). Water extracts from the leaves of the Gala and Gloster cultivars had the significantly lowest content of phenolic compounds in extracts made using the UAE method (approx. 35 mg GAE/1 g of DW). Among the water extracts, the extract from the leaves of the Ligol v cultivar had the significantly highest content of polyphenols (43 mg GAE/1 g of DW).  
A two-factor analysis of variance showed that not only did the type of solvent used have a significant impact on the content of total polyphenols in the extracts but also the cultivar of apple leaves, the significant impact of which could only be determined after taking into account both factors and their interaction.  
[PERSON] et al. [18], examining methanol extracts made using ultrasound-assisted extraction from healthy apple leaves of the Golden Delicious and Jonagold cultivars, collected in the last days of July, obtained very similar results. The content of total polyphenols was 76 mg GAE/1 g of DW in extracts from the Golden Delicious v cultivar and approximately 60 mg GAE/1 g of DW in extracts from the Jonagold cultivar. [PERSON] and [PERSON] [8] also obtained similar results in their study. In 30% water-alcohol extracts, they determined from 73.3 (in the Szampion cultivar) to 115.8 mg GAE/1 g of DW (in the Ozark Gold cultivar) of total polyphenols. However, [PERSON] et al. [41], similarly to the present study, determined significantly less polyphenols in water extracts from apple leaves than in water-ethanol extracts.