## 5 Conclusions  
Studies have demonstrated the biocidal activity and high antioxidant potential of the silver birch (_Betula pendula_ Roth) leaf preparation with a reduced ethanol content. The _Betula pendula_ preparation, due to the presence of phenolic acids and volatile biologically active compounds, exhibits antioxidant and antimicrobial activity against reference bacteria and fungi. The presence of phenolic acids makes the preparation highly hydrophilic, as evidenced by a log P = \(-\)0.500 \(\pm\) 0.001.  
Using the new antiseptic lotion to clean people's hands according to PN-EN 1500:2013 showed that it was effective against _Escherichia coli_ K12 NCTC 10538. The mean 60 s kill time was >99.9% for the new antiseptic against _Staphylococcus aureus_ ATCC 6538 (at a concentration of 30 g/100 mL) and _Pseudomonas aeruginosa_ ATCC 15442 (at a concentration of 40 g/100 mL). Polypphenols are considered highly effective against bacteria, but the thicker cell wall and larger cell structure may slow down the antimicrobial effect of the preparation against Gram-positive bacteria compared to Gram-negative bacteria.  
Furthermore, the high content of polyphenols and other biologically active compounds may be one of the parameters responsible for the effective biological activity of the preparation, which supports the use of a balanced product in healthcare facilities, schools, or homes. Moreover, its high antioxidant potential allows its use in the cosmetic and pharmaceutical industries.  
The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app15073658/s1](https://www.mdpi.com/article/10.3390/app15073658/s1)]([https://www.mdpi.com/article/10.3390/app15073658/s1](https://www.mdpi.com/article/10.3390/app15073658/s1)): Table S1. The content (Mean \(\pm\) SD) of phenolic acids in _Betula pendula_ extract (n = 3); Figure S1. The representative of chromatographs identifies individual phenolic acids in the preparation from _Betula pendula_: gallic acid, RT = 5.962 min; 3,4-dihydroxybenzoic acid, RT = 12.042 min; 2,5-dihydroxybenzoic acid, RT = 14.274 min; chlorogenic acid, RT = 18.022 min; and 3-hydroxybenzoic acid, RT = 24.092 min.; Figure S2. The representative chromatogram of the preparation from the leaves of _Betula pendula_ containing: 1--palmitic acid (RT = 15.62 min); 2--ethyl palmit (RT = 15.82 min); 3--phytol (RT = 16.86 min); 4--linolenic acid (RT = 17.01 min); 5--methyl linoleate (RT = 17.15 min); 6--ethyl linoleate (RT = 17.19 min); 7--hexacosanol (RT = 19.01 min); 8--alpha-Tocospiro B (RT = 20.97 min); 9--sitosterol (RT = 24.28 min); 10--cabraleadiol (RT = 26.65 min); 11--dilauryl thiodipropionate (RT = 26.76 min); Figure S3. An example of the UV-Vis spectrum of an extract obtained from _Betula pendula_.  
Conceptualization, L.K. and E.K.; writing--review and editing, L.K., A.M.-S., A.N. and E.K.; methodology, L.K. and A.N.; review, R.P.; formal analysis, L.K., E.K. and A.N.; writing--original draft preparation, L.K., A.N., E.K. and A.M.-S.; and supervision, R.P. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
**Institutional Review Board Statement**: Not applicable.  
**Informed Consent Statement**: Not applicable.  
**Data Availability Statement**: The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
**Conflicts of Interest**: The authors declare no conflicts of interest.