## 3 Results and Discussion
### Biological Activity of Emulsions  
Emulsions containing essential oils exhibit a range of biological activities depending on the chemical composition and properties of both the essential oils and the emulsion system. Research has shown that clove essential oil represents a high antioxidant activity in vitro and in vivo. Eugenol is the main component of clove essential oil and the main contributor to the biological effects of clove essential oil [46]. Clove essential oil can inhibit lipid peroxidation in foods, reduce oxidative stress, and is considered safe for use in food, cosmetics, and pharmaceutical applications for a wide range of beneficial health promotion activities [47]. Meanwhile, cinnaldehyde is already known for its high antimicrobial action [6]. It can be used in pharmaceuticals, cosmetics, personal care, and cleaning products in the European Union [48]. Moreover, clove essential oil, eugenol, and cinnaldehyde are generally recognized as safe and approved by the Food and Drug Administration of the United States [49].  
In this work, the antioxidant properties of the emulsions were investigated using the DDPH method, and the obtained results were expressed as radical scavenging activity (%). As can be seen from Figure 3, free radical scavenging activity depended on the active component used in the emulsion. The highest activity was determined for the EM-CL (79-83%) and EM-EU (80-88%) emulsions. Meanwhile, samples containing CI did not show significant antioxidant properties, and the radical scavenging activity varied from 1 to 4% only. Mainly, the chemical structure of compounds influences the capacity of antioxidant activity. Phenolic compounds including eugenol are known for their strong antioxidant properties because the hydroxyl group can donate hydrogen atoms to free radicals, thereby neutralizing them [50]. On the other hand, cinnamo aldehyde contains an aldehyde functional group which may also contribute to its antioxidant activity through different mechanisms; however, with relatively low radical scavenging activity compared to emulsions containing eugenol or clove oil [51].  
The emulsions containing 10% of CL, EU, or CI were tested for their antimicrobial activity against Gram-negative (_Escherichia coli_) and Gram-positive (_Staphylococcus aureus_, _Listeria monocytogenes_, _Bacillus cereus_) bacteria as well as yeasts (_Candida albicans_) and MIC and MBC were established (Table 4). The establishment of MIC and MBC values  
Figure 3: The radical scavenging activity (%) of various emulsions. a–d: the different letters for different emulsions show that the results are significantly different (_p_ < 0.05; Duncan test).  
demonstrated that emulsions containing 10% of CL, EU, or CI had bacteriostatic and bactericidal activity on the tested bacteria strains as was shown by the inhibition of the growth and the killing of \(\geq\)99.9% bacteria at certain concentration (Table 4).  
The lowest MIC (0.125 mg/mL) was characteristic of the emulsion containing EU for _S. aureus_. Meanwhile, the lowest MIC (0.125 mg/mL) and MBC (0.25 mg/mL) values of emulsion containing CI were for eukaryotic cell--_Candida albicans_.  
The comparison of MBC and MIC values for Gram-positive bacteria _S. aureus_ showed that the MBC/MIC ratio was > 4 for EM-CL-10 and EM-EU-10. Such an effect was considered bacteriostatic. Meanwhile, the MBC/MIC ratio determined for the emulsions against _E. coli_ and _L. monocytogenes_ was \(\leq\)4, indicating the bactericidal effect.