Tony Picoli

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 2 μg/mL and 8 μg/mL, respectively, and the MFC50 and MFC90 were 2 μg/mL and >16 μg/mL, respectively, with three S. brasiliensis isolates resistant to antifungal. S. schenckii was sensitive at MIC of 1 μg/mL and MFC of 8 μg/mL. For the oil of O. majorana L., all isolates were susceptible to MIC of ≤2.25–9 mg/mL and MFC of ≤2.25–18 mg/mL. The MIC50 and MIC90 were ≤2.25 mg/mL and 4.5 mg/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 5 mg/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.

Polar Origanum vulgare (Lamiaceae) extracts with antifungal potential against Sporothrix brasiliensis

&NA; Oregano (Origanum vulgare) has anti‐Sporothrix spp. activity, including against strains that are resistant to antifungal drugs. As the studies are limited to the essential oil, the aim of this study was to evaluate the chemical, antioxidant and cytotoxic properties of polar oregano extracts and their anti‐Sporothrix brasiliensis activity. Aerial plant parts were used in the preparation of 10 min (INF10) and 60 min (INF60) infusions, a decoction (DEC) and a hydroalcoholic extract (HAE). Six phenolic acids and four flavonoids were identified and quantified through liquid‐chromatography (LC‐MS). Extracts in increasing order of total phenolic and flavonoid contents were HAE<INF60<INF10<DEC and HAE<DEC<INF60<INF10, respectively. All extracts showed DPPH and ABTS radical scavenging potential (HAE<INF60<DEC<INF10). HAE showed the least toxicity toward MDCK and CRFK cell lines in the MTT colorimetric assay. The antifungal potential against 29 S. brasiliensis isolates obtained from cats and dogs was evaluated following the CLSI M38‐A2 protocol adapted to natural products. Minimum inhibitory concentration for 50% of the isolates (MIC50) was 5 mg/ml for all extracts, and minimum fungicidal concentration for 50% of the isolates (MFC50) was 20 mg/ml for INF10 and 40 mg/ml for the remaining extracts. MIC90 was 10 mg/ml for all extracts, except for DEC (20 mg/ml). MFC90 was 40 mg/ml for INF10 and > 40 mg/ml for the other extracts. This is the first report of oregano extracts showing antifungal activity against S. brasiliensis. Its use in the treatment of sporotrichosis may be considered upon toxicity and safe‐use conditions are tested.