## 4 Discussion  
The studies on eugenol and isoeugenol, two terpene compounds found in various plants, including cloves, underline their significant potential as natural preservatives in cosmetic products. Their pronounced antibacterial and antifungal properties make them promising alternatives to conventional synthetic preservatives, which have been increasingly criticized due to their allergenic effects and potential long-term health risks [30; 34]. In the context of skin care, eugenol and isoeugenol show strong inhibitory effects against several Gram-positive bacterial strains, such as _Staphylococcus aureus_ and _Enterococcus faecalis_, both of which are commonly associated with skin and hospital infections. These findings emphasize the need for effective preservatives in cosmetic products, as they help prevent contamination by harmful microorganisms. Additionally, the efficacy of eugenol and isoeugenol against yeast-like microorganisms, such as _Candida albicans_, suggests a broad spectrum of action, making them suitable for use in products susceptible to microbiological contamination, especially in humid environments such as cosmetics [33; 35; 42]. The antimicrobial mechanism of action of eugenol and isoeugenol is attributed to their ability to disrupt microbial cell membranes. This disruption leads to increased membrane  
Figure 9: Anticancer profile of the U87 MG cell line (human glioma cells) treated with eugenol (EU) and isoeugenol (ISO-EU) in the concentration range from 10 to 200 ng/mL. The graph illustrates the dose-dependent reduction in cell survival with a linear approximation of the data points, indicating a consistent, linear relationship between the concentration of these compounds and the decrease in cell viability. permeability and, ultimately, cell rupture. Such a mechanism facilitates the leakage of essential intracellular components, including ions and proteins, which disrupts the cellular processes necessary for microbial survival. These results are consistent with previous studies, which have suggested that eugenol acts on both the structural integrity and the functional properties of cell membranes, further validating its potential as a natural preservative [37]. Furthermore, studies have demonstrated the effectiveness of eugenol and isoeugenol as preserves in cosmetic formulations. Their ability to inhibit microbial growth in cream samples, even at varying concentrations, is particularly notable. The absence of detectable microbiological contamination in these formulations suggests that eugenol and isoeugenol can effectively protect cosmetics from contamination, providing a natural alternative to synthetic preservatives. This is especially important in the context of increasing consumer demand for natural, eco-friendly products that align with sustainability trends [31; 38]. Incorporating eugenol and isoeugenol into cosmetic formulations offers the potential to reduce reliance on synthetic preservatives, which are often associated with safety concerns and regulatory scrutiny. Natural alternatives like eugenol not only enhance the safety of cosmetic products but also cater to consumer preferences for simpler, more transparent ingredient lists in personal care products [34; 36]. In addition to their preservative qualities, eugenol and isoeugenol have demonstrated cytotoxic effects on cancer cell lines, such as LoVo (colon cancer) and U87 MG (glioblastoma), in a concentration-dependent manner. This discovery opens new avenues for research into the dual functionality of these compounds, which could have applications both in cosmetics and cancer therapy. Optimizing their concentrations to achieve antimicrobial efficacy while minimizing cytotoxic effects on healthy cells presents an exciting direction for future research [39; 42]. Considering the ongoing global challenge of antibiotic resistance, eugenol, and isoeugenol may provide valuable alternatives to conventional antimicrobial agents.