Chemical profile, stability and fungicide activity of oil-in-water nanoemulsion (O / A) incorporated with Ba-har essential oil

Abstract

The increase in strains resistant to conventional antifungals means that there is a need for studies related to alternative therapeutic practices, such as medicinal plants. This study aims to evaluate the chemical profile and fungicidal activity of the nanoemulsion of the essential oil obtained from Ba-har (Syrian pepper). The phytochemical profile of the plant material was performed based on the methodology of Matos (2009). For extraction of essential oil, 100g of plant material was used, with the isolation of essential oil by the hydrodistillation technique conducted at 100 °C / 3h. To quantify the total phenolics present in the OE, the Folin-Ciocalteu method was used. For the total flavonoids, the AlCl3 complexation method was used. The oil-in-water nanoemulsion was formulated by the low-energy method of phase inversion using essential oil, non-ionic surfactant and water, and the obtained nanoemulsion was subjected to thermodynamic stability tests. The essential oils and stable nanoemulsions were subjected to evaluation of the fungicidal action against strains of Aspergillus niger (ATCC 6275), Colletotrichum gloeosporioides (ATCC 96723) and Penicilium chrysogenum (ATCC 10106). The fungicidal activity was performed according to CLSI (2020) using the Broth Dilution method to obtain the Minimum Inhibitory Concentration (MIC) and sowing on agar for Minimum Fungicidal Concentration (CFM). The results obtained for the total phenolic content were quantified at 348.3 mg EAT g-1 and 346.21 mg EQ g-1 for flavonoids. Ba-har essential oil was more efficient in inhibiting A. niger, as it presented the lowest MIC (200 µg mL-1), followed by P. chrysogenum (250 µg mL-1) and later by C. gloeosporioides (300 µg mL-1). The identification of the secondary metabolites present in Ba-har was quite considerable, since they are responsible for the biological properties, thus inspiring the continuity of studies related to its biological activities. As for the total phenolic content and flavonoids present in the essential oil, they indicated the important antioxidant potential. The fungicidal potential of Ba-har oil showed strong inhibition and mortality, however the nanoemulsion product with the essential oil incorporated showed a more efficient action against the pathogenic fungi tested,