Antibacterial and Antioxidant Activity of Basil (Ocimum basilicum), Lemongrass (Elionurus muticus), and Pitanga (Eugenia uniflora) Essential Oils ^†

Introduction: Essential oils (EO), present in leaves, flowers, stems, and roots, are rich in terpenes and phenolic compounds, conferring antimicrobial and antioxidant activities. With the increase in microbial resistance, the demand for new bioactive agents has intensified. This study aimed to evaluate and compare the antimicrobial and antioxidant activities of basil (BEO), lemongrass (LEO), and pitanga (PEO) EO. Methodology: Commercial BEO, LEO, and PEO from southeastern Brazil were tested against Staphylococcus aureus, five Gram-negative bacteria (Escherichia coli, Salmonella enterica, K. pneumoniae, A. baumannii, P. aeruginosa), and two yeasts (Candida albicans, Candida krusei). The minimum inhibitory concentration (MIC), minimum bactericidal/fungicidal concentration (MBC/MFC), and disk-diffusion inhibition zones were determined. Antioxidant activity was evaluated by ABTS and DPPH radical scavenging assays; total phenolic content was measured. Results: BEO was most effective against E. coli and S. enterica (MIC 0.66 mg/mL; MBC 2.56–15.53 mg/mL). LEO had the lowest MICs for Candida spp. (<0.55 mg/mL) and S. aureus (1.50 mg/mL), with the largest zone of inhibition for S. aureus (33.56 ± 0.40 mm). PEO was most active against A. baumannii (MIC 0.25 mg/mL; MBC 2.34 mg/mL). Yeast zones of inhibition ranged from 6.67 ± 4.45 to >28.98 ± 1.94 mm; K. pneumoniae was the most resistant (8.84–15.13 mm). For ABTS, BEO (922.40 ± 17.50 µmol.TE/mL) and PEO (853.62 ± 29.74 µmol.TE/mL) showed the highest activity, with BEO presenting the highest phenolic content (107.56 ± 1.89 mg.GAE/mL). Conclusion: All three EO demonstrated complementary antimicrobial and antioxidant potential. Future studies should explore synergistic effects between BEO, LEO, and PEO to enhance efficacy against multidrug-resistant pathogens.