<em>Ocimum campechianum</em> essential oil: chemical composition and antifungal activity against filamentous fungi

Abstract

Ocimum campechianum (OC), an aromatic and medicinal plant from the Amazon region, is rich in essential oils with antimicrobial potential. This study aimed to analyze the quality, toxicity, and antifungal action of Ocimum campechianum essential oil(OCEO). The plant species were collected in the city of São Luís-MA (Brazil). The essential oil (EO) was extracted by hydrodistillation in a Clevenger apparatus, and the physical-chemical parameters were analyzed according to the Brazilian Pharmacopoeia norms. The essential oil constituents were identified by gas chromatography-mass spectrometry (GC-MS). Toxicity was evaluated against brine shrimp (Artemia salina Leach). The antifungal activity was evaluated by the method of disk diffusion and microdilution in broth against ATCC strains of filamentous fungi Aspergillus Niger (ATCC 6275), Colletotrichum gloeosporioides (ATCC 96723), and Penicillium chrysogenum (ATCC 10106. The essential oil showed a slightly yellowish color, intense clove aroma, a density of 1.0 ± 0.0 g/mL, a refractive index of 1.52 ± 0.00, solubility in ethanol (1:2), and a yield of 1.40%. The chromatographic profile showed 36 volatile compounds, the majority being eugenol (49.18%), followed by β- caryophyllene (17.26%), elixene (9.46%), methyl eugenol (7.65%), and eucalyptol (2,55%). It presented LC 50 = 955 μg / mL against Artemia salina. The fungi induced growth inhibition zones (14.90 to 17.85 mm). The fungus P. chrysogenum was the most susceptible (MIC 220 μg/ml) compared to the fungi A. niger (MIC 250 μg/mL) and C. gloeosporioides (MIC 270 μg/mL). The minimum fungicide concentration (MFC) was sufficient to inhibit the growth of P. chrysogenum at 380 μg/mL, A. niger at 400.25 μg/mL, and C. gloeosporioides at 416.66 μg/mL. The OCEO showed good quality, low toxicity, and fungicidal action against the filamentous fungi analyzed, suggesting its application as a promising natural antifungal, mainly in combating diseases in post-harvest crops.