Speaker
Description
The escalating threat of antimicrobial resistance (AMR) presents a critical challenge to modern medicine and underscores the urgency of exploring alternative therapeutic strategies. Essential oils (EOs), rich in bioactive secondary metabolites, are recognized for their antioxidant and antimicrobial activities. However, their practical use is limited by volatility and susceptibility to environmental degradation. Nanoencapsulation offers a promising approach to enhance EO stability and bioactivity. This study investigates the chemical composition, antioxidant capacity, and antimicrobial activity of EOs extracted from three varieties of Terminalia catappa fruit pulp and three varieties of leaves from Ghana. A nanoemulsion based delivery system was developed to improve stability and potency. EOs were obtained via steam distillation and evaluated for antioxidant potential using the phosphomolybdenum (PM) assay, DPPH (1,1 diphenyl 2 picrylhydrazyl) radical scavenging, and hydrogen peroxide scavenging assays. Leaf EOs exhibited total antioxidant capacities of 26.112 ± 2.231, 26.819 ± 1.753, and 32.770 ± 1.663 mg AAE/100 g, while fruit pulp EOs recorded 27.807 ± 3.301, 24.181 ± 2.032, and 25.441 ± 1.914 mg AAE/100 g. DPPH scavenging IC₅₀ values for leaf EOs were 141.2 ± 1.112, 136.9 ± 3.123, and 180.6 ± 2.150 µg/mL, compared to 197.1 ± 2.980, 165.5 ± 1.278, and 194.0 ± 1.512 µg/mL for fruit pulp EOs. In hydrogen peroxide scavenging, fruit pulp EOs showed stronger activity (48.40 ± 0.341, 115.4 ± 3.432, and 101.8 ± 1.203 µg/mL) than leaf EOs (145.6 ± 2.131, 182.2 ± 2.154, and 70.28 ± 0.781 µg/mL). Antimicrobial activity, assessed by minimum inhibitory concentration (MIC), ranged from 20.5–41 mg/mL for leaf EOs and 25–50 mg/mL for fruit pulp EOs, with leaf EOs generally showing greater potency. Nanoemulsions were formulated and characterized by droplet size (26.43–218.1 nm), polydispersity index (0.334–0.397), and zeta potential (−9.88 to −21.8 mV). Nanoencapsulation markedly improved antimicrobial efficacy, reducing MIC values to 7.5–15 mg/mL compared with unencapsulated oils. Ongoing work includes detailed characterization of the EO constituents and evaluation of the antioxidant potential of the nanoencapsulated formulations. These results indicate that T. catappa EOs, particularly in nanoemulsion form, are promising natural antimicrobial agents with potential applications in addressing AMR related threats.