Enhancing antioxidant and antibacterial activities of Cuminum cyminum, Origanum vulgare, and Salvia officinalis essential oils through a synergistic perspective

Essential oils (EOs) from aromatic and medicinal plants have antioxidant and antibacterial properties and are commonly used as preservatives in the food industry. Combining EOs can produce a synergistic effect, enabling their application as condiments at reduced dosages. Therefore, this study aimed to evaluate the antioxidant and antibacterial activities of the combination of three EOs extracted from Sage (Salvia officinalis), Oregano (Origanum vulgare), and Cumin (Cuminum cyminum). This experiment involved a three-factor simplex lattice design comprising 14 experimental runs with three replications. Gas chromatography-mass spectrometry (GC-MS) analysis identified carvacrol (39.54%) and gamma-terpinene (23.22%) as the principal components of the EO from O. vulgare, while cumin aldehyde (24.24%) and lavandulyl acetate (19.56%) and gamma-terpinene (18.78%) were dominant in the EO of C. cyminum; additionally, S. officinalis exhibited alpha-thujene (34.85%) and pinocarvone (18.44%) as its main constituents. The optimal conditions for the independent variables were established at 15.0553% for C. cyminum, 74.0453% for O. vulgare, and 10.90% for S. officinalis. These conditions resulted in notable increases in antioxidant activity, as demonstrated by a DPPH scavenging activity of 88.1% and a FRAP assay value of 11.3 mu mol Fe(II)/g dry weight (DW). Additionally, the optimal conditions yielded significant inhibition zones against various bacterial strains, measuring 18.59 mm for Salmonella enterica, 22.97 mm for Escherichia coli, and 19.26 mm for Staphylococcus aureus. The predictive models showed high and statistically significant regression coefficients for all the parameters (p < 0.05). The measured parameters were in close agreement with the predicted values from the quadratic polynomial equation. Correlation analysis tools can effectively identify EOs' synergistic properties and predict active compounds' optimal characteristics. These findings confirm that the antioxidant and antibacterial activities are enhanced through the synergistic combination of EOs, underscoring their potential as effective natural preservatives in industrial applications.