# Antioxidant and Antibacterial Activity of Extracts from Selected Plant Material
## 3 Results and Discussion
### Extraction Yield and Total Phenolics Content (TPC)
Maceration increased the TPC content to 90.1 mg GAE/g dry material and the use of hydroalcoholic solvents allowed the phenolic compounds in lemon balm extracts to be estimated at 227.6 mg GAE/g dry material. In addition, aqueous extraction of _Melissa officinalis_ using a pulsed electric field followed by ultrasound increased the content of TPC [40]. In another study carried out for aqueous extract of lemon balm, TPC ranged from 5.55 to 49.19 mg GA/g depending on temperature and extraction time and was almost three times lower than the values obtained in our experiments [41]. In contrast, aqueous ethanolic extracts from white mulberry and _B. pendula_ leaves, and _A. europaeum_ herb showed statistically significant (\(p<0.05\)) differences in total polyphenol content. In this group of extracts, the highest polyphenol content was found in the _B. pendula_ leaf extract and the lowest in the mulberry leaf extract. The high polyphenol content in _B. pendula_ dry leaf extracts was also observed by [PERSON] et al. [26]. However, it was higher compared to our study and significantly influenced the ability of these extracts to reduce free DPPH radicals. On the other hand, the total polyphenol content in the powdered extracts from white mulberry leaves from Poland was similar to the values obtained in our experiment and amounted to 42.6 mg GAE/g DM [42]. Similar TPC values were also determined for leaf extracts of mulberry belonging to one of the three cultivars from the South China studied [21]. On the other hand, the ethanol-water leaf extract of _M. alba_ from Poland was three-fold higher than in our extract [43]. The content of phenolic compounds in extracts obtained from a plant material is influenced by many factors, including geographical origin, location, climate conditions, harvest time or the way the plant material is dried. The manner in which the extraction process is carried out, i.e., time, temperature, type of solvent used, its polarity and the part of the plant subjected to this process, also play an important role. Choosing a solvent that is safe, cheap, non-toxic and able to extract phenolic compounds with the highest efficiency is particularly important in the food industry. Often, the use of a mixture of solvents may be more effective in the extraction of phenolic acids and flavonoids. Therefore, in this study, ethanol in combination with water was chosen. This type of mixture was also chosen for the extraction of phenolic compounds from _C. incanus_ growing in Strandja Mountain [44]. The TPC expressed as gallic acid and tannic acid equivalents in the extracts varied between 36.26 and 115.32 mg GAE/g d.w. and 71.88 and 228.56 mg TAE/g d.w. as a function of time, respectively. The highest content of phenolic compounds was found when a 30% ethanol solution was used and the extraction process was carried out for 390 min. Similar to our research results for TPC were obtained for _C. incanus_ extracts prepared using 60% methanol in Soxhlet apparatus (331.82-347.27 mg GAE gd.w.) [45] and for aqueous and hydromethanonic extracts of _C. salviofilus_ (408.43 \(\pm\) 1.09 and 336.51 \(\pm\) 1.22 mg GAE/g of extract dry weight, respectively) [46]. Lower levels of TPC were reported for the aqueous and hydromethanonic extracts of _C. incanus_ grown in Turkey. It was also observed that the aqueous extracts of _Cistus_ species were richer in phenolic compounds than their hydromethanonic counterparts [47].