Comparison of Antioxidant, Antibacterial, and Cytotoxic Effects of Essential Oil and Nanoemulsion of Clove Essential Oil

Medicinal plants are among the most important products in agriculture and medicine. The usefulness and cheapness, environmental friendliness, and limited side effects of medicinal plants have increased the rate of use of these plants in recent years. Plant extracts, such as cloves, have long been used in medicine, perfumery, and as additives in cooking. This study aimed to evaluate and compare the antioxidant, antibacterial, and anti-cancer effects of clove essential oil and nanoemulsion.

Antioxidant activity of essential oil and clove nanoemulsion by measuring the inhibitory activity of DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS radicals (2 and 2-azino-bis-3-ethyl benzothiazoline-6-sulfonic acid) was measured in this study. The evaluation of antibacterial and bactericidal properties of essential oil and clove nanoemulsion was conducted by culture medium and suspension of four pathogenic bacteria of gram-positive, including Staphylococcus aureus and Bacillus subtilis, and gram-negative bacteria, including Escherichia coli and Pseudomonas aeruginosa, followed by the measurement of the diameter of the growth inhibition zone. In addition, the effects of cytotoxicity of clove essential oil and nanoemulsion on different concentrations of 15.6, 31.2, 62.5, 125, and 250 μg/ml on MCF7 cancer cells were evaluated by MTT staining.

Clove nanoemulsion, compared to essential oil, had good antioxidant potential and a significant effect on free radical scavenging. The rates of free radical scavenging (IC50) of clove essential oil nanoemulsion were obtained at 67.29 and 78.39 μg/ml measured by DPPH and ABTS methods, respectively. Clove essential oil and nanoemulsion had an inhibitory effect on both groups of gram-positive and gram-negative bacteria tested in this study. The toxicity test also showed a greater effect of clove nanoemulsion in killing breast cancer cells, compared to the clove essential oil. 

The results of this in vitro study indicate the antioxidant and anti-cancer effects of clove nanoemulsion, compared to essential oil, which can be used to prevent and treat many diseases associated with the development of reactive oxygen species.