## 1 Introduction
The permissible limits of microorganisms in cosmetics are defined by legal regulations, such as EU Regulation No. 1223/2009 on cosmetics. These guidelines also provide information on storing cosmetics under appropriate conditions to prevent microbial growth [1; 5]. The skin microbiome is a collection of microorganisms--primarily bacteria, fungi, and viruses--that naturally exist on the surface of human skin. This microbiome plays a crucial role in protecting the skin from pathogens, regulating the immune responses, and maintaining the skin moisture balance. A proper balance of the skin microbiome can help prevent skin disorders such as acne, eczema, and psoriasis. Eugenol and isoeugenol, which possess antimicrobial properties, can interact with the skin microbiome, particularly in the context of their use in cosmetic products. Eugenol, the main component of clove essential oil, exhibits bactericidal, fungicidal, and antiviral effects, which may help to reduce the presence of unwanted microorganisms on the skin, such as _Staphylococcus aureus_ and _Candida albicans_[6; 10; 27]. However, excessive use of eugenol can disrupt the balance of the skin microbiome, leading to the dominance of certain microorganisms, which could result in skin reactions such as irritation or contact allergies. In the case of isoeugenol, although its properties are similar to eugenol, it may exhibit slightly different interactions with the skin microbiome, which requires further study [25; 28]. Eugenol and isoeugenol are widely used in cosmetics as fragrance ingredients and substances with anti-inflammatory, antimicrobial, and skin-soothing properties. Numerous studies confirm their effectiveness in skin care, especially in products for oily and acneprone skin. However, attention should be paid to the relevance of the cited references regarding these compounds in the context of cosmetics. It is essential to evaluate whether these studies are up-to-date, conducted on the appropriate skin models, and whether they consider potential risks such as irritation or skin allergies, which may result from prolonged use of these substances. It is also important that the cited studies are conducted in accordance with the current safety standards and regulations for cosmetic products, such as EU Regulation No. 1223/2009, which requires thorough testing of the toxicity of ingredients and their impact on consumer health [2; 3; 4]. Eugenol and isoeugenol are widely used in cosmetics, pharmaceuticals, and food products, but the regulations governing these three industries differ significantly. In cosmetics, eugenol is mainly used in skin care products such as creams, gels, and tonics due to its soothing, anti-inflammatory, and antibacterial properties, and is also present in essential oils. In pharmaceutical products, eugenol and isoeugenol are used to treat inflammatory conditions, toothache, and upper respiratory infections. The differences in regulations for cosmetics, pharmaceuticals, and food products are important because each of these industries has its own guidelines regarding the concentration of active substances, safety of use, permissible toxicity levels, and methods of application. For example, in cosmetics, eugenol can be used in concentrations of up to 1%, whereas in pharmaceutical preparations, these concentrations can be much higher [32; 33; 39]. Additionally, in food products, eugenol is used as the flavoring agent, but its concentration must be strictly controlled to ensure it does not exceed the permissible safety limits [31; 34; 35]. The aim of our work was as follows:  
1. Assessing the antimicrobial potential of eugenol and isoeugenol against the selected Gram-positive bacteria, Gram-negative bacteria, and fungi. We conducted experiments using pure, commercially available eugenol and isoeugenol to determine their efficacy.