Litsea cubeba essential oil: chemical profile, antioxidant activity, cytotoxicity, effect against Fusarium verticillioides and fumonisins production.

The purpose of this study was to determine the chemical profile of Litsea cubeba essential oil, carry out an in vitro evaluation of its antioxidant potential and its cytotoxicity, as well as its antifungal and antimicotoxigenic activities against Fusarium verticillioides. Most of the compounds observed in the EO were neral (32.75%) and geranial (37.67%). The radical scavenging capacity of 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid was 104.4 and 56.4 mmol Trolox mg-1, respectively, indicating good antioxidant activity. The EO studied by us revealed cytotoxic effect against HT-29 and HeLa cancer cells. The Minimum Inhibitory and Minimum Fungicidal Concentrations against F. verticillioides were both 125 µg mL-1. Morphological investigation, performed by fluorescence microscopy and scanning electron microscopy, showed that hyphae and microconidia structures underwent changes after treatment with the EO. Analyses performed with the EO strongly reduced the mycelial development of F. verticillioides and the synthesis of fumonisins B1 and B2 in dose-dependence effect compared (P < 0.01) with the fungal control (105 conidia mL-1) and positive control (fludioxonil + metalaxyl-M). Thus, the results obtained in vitro suggest that L. cubeba EO has excellent antioxidant, fungicidal, and antimycotoxigenic effects.

Antifungal and antimycotoxigenic effects of Zingiber officinale, Cinnamomum zeylanicum and Cymbopogon martinii essential oils against Fusarium verticillioides.

There is an increasing demand for fungi control in grains, especially toxigenic. Also, there is growing concern on the use of synthetic fungicides; thus alternatives are needed. The aim of this study was to evaluate the antifungal and antimycotoxigenic action of essential oils (EOs) from Zingiber officinale, Cinnamomum zeylanicum and Cymbopogon martinii against Fusarium verticillioides, a spoilage and toxigenic fungus. Essential oils were first chemically characterised by gas chromatography coupled to mass spectrometry, and their antioxidant potential was measured by the DPPH, ABTS and FRAP methods. Minimum inhibitory concentration (MIC) and disc diffusion were used to assess antifungal activity. Scanning electron microscopy was used to evaluate morphological changes in the fungus. Antimycotoxigenic activity of the EOs against the production of fumonisin B1 and B2 by F. verticillioides was evaluated using ultra-high-performance liquid chromatography system. Z. officinale, C. zeylanicum and C. martinii EOs were predominantly composed by zingiberene and geranial; eugenol; and geraniol, respectively. All the EOs had high antioxidant power, especially that from C. zeylanicum. The MICs were 250, 500 and 2,000 µg mL-1 for C. zeylanicum, C. martinii and Z. officinale EOs, respectively. Mycelial reduction of F. verticillioides was observed when EOs were used, and the lowest activity was detected in the Z. officinale EO. Overall, the tested EOs promoted structural damage to the fungal cell wall, decreased conidia size and mycelial reduction. Antimycotoxigenic evaluation of the EOs evidenced a significant reduction (p < .05) in the production of fumonisins B1 and B2 with all the EOs evaluated in the study. These results suggest that especially C. zeylanicum and C. martinii EOs are highly useful for controlling F. verticillioides and fumonisins production.