Rosalina, Niaouli and Fir Essential Oils: Strong Antifungal but Weak Antioxidant Activity

Antioxidant and antifungal activities of three essential oils (EOs): Melaleuca ericifolia Smith (rosalina; REO), Melaleuca quinquenervia (niaouli; NEO) and Abies alba (fir; FEO) were determined. The antioxidant capacity was investigated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and the disc diffusion method was applied to evaluate their antifungal efficacy (in four concentrations 62.5 μL/L, 125 μL/L, 250 μL/L, 500 μL/L used) against Penicillium (P.) expansum microscopic filamentous fungus isolated from bread samples. From the findings it can be clearly evident that antioxidant activities of the EOs were very weak with values ranging from 25.81 ± 7.8 TEAC (6.2 ± 1.4%; FEO) to 162.0 ± 2.1 TEAC (15.9 ± 0.4%; NEO). Regarding antifungal properties, our results revealed that the effects of the EOs on P. expansum growth inhibition were dose-dependent, and they were proportionally increased with increasing EOs concentrations. Detected inhibition zones ranged from 0.00 ± 0.00 mm (for all EOs at 62.5 μL/L) to 11.67 ± 1.15 mm (for REO at 500 μL/L). In conclusion, all analyzed EOs possess promising in vitro antifungal activity (despite their weak antioxidant capacity) suggesting their use as a promising natural preservative in the food industry.