Cytotoxicity and anti-Sporothrix brasiliensis activity of the Origanum majorana Linn. oil.

The study aimed to evaluate the anti-Sporothrix sp. activity of the essential oil of Origanum majorana Linn. (marjoram), its chemical analysis, and its cytotoxic activity. A total of 18 fungal isolates of Sporothrix brasiliensis (n: 17) from humans, dogs and cats, and a standard strain of Sporothrix schenckii (n: 1) were tested using the broth microdilution technique (Clinical and Laboratory Standard Institute - CLSI M27-A3) and the results were expressed in minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC). The MIC50 and MIC90 of itraconazole against S. brasiliensis were 2μg/mL and 8μg/mL, respectively, and the MFC50 and MFC90 were 2μg/mL and >16μg/mL, respectively, with three S. brasiliensis isolates resistant to antifungal. S. schenckii was sensitive at MIC of 1μg/mL and MFC of 8μg/mL. For the oil of O. majorana L., all isolates were susceptible to MIC of ≤2.25-9mg/mL and MFC of ≤2.25-18mg/mL. The MIC50 and MIC90 were ≤2.25mg/mL and 4.5mg/mL, respectively, and the MFC50/90 values were twice more than the MIC. Twenty-two compounds were identified by gas chromatography with a flame ionization detector (CG-FID) and 1,8-cineole and 4-terpineol were the majority. Through the colorimetric (MTT) assay, the toxicity was observed in 70-80% of VERO cells between 0.078 and 5mg/mL. For the first time, the study demonstrated the satisfactory in vitro anti-Sporothrix sp. activity of marjoram oil and further studies are needed to ensure its safe and effective use.