Antifungal and antiocratoxigenic potential of Alpinia speciosa and Cymbopogon flexuosus essential oils encapsulated in poly(lactic acid) nanofibres against Aspergillus fungi.

Essential oils encapsulated in a polymeric matrix can be used as an alternative method to control fungi and mycotoxins. The essential oils were extracted by hydrodistillation and characterized by gas chromatography. The nanofibres were produced from poly (acid lactic) (PLA) containing essential oils by the Solution Blow Spinning method. The antifungal and antimicotoxygenic properties were evaluated against Aspergillus ochraceus and Aspergillus westerdijkiae by the fumigation method. Terpinen-4-ol (20·23%), sabinene (20·18%), 1·8-cineole (16·69%) and γ-terpinene (11·03%) were the principal compounds present in the essential oil from Alpinia speciosa, whereas citral (97·67%) was dominant from Cymbopogon flexuosus. Microscopy images showed that the addition of essential oils caused an increase in the diameter of the nanofibres. The infrared spectroscopy results indicated the presence of essential oils in the PLA nanofibres. Differential scanning calorimetry curves also indicated the existence of interactions between the essential oils and polymeric macromolecules through their plasticizing action. The hydrophobic character of nanofibres was revealed by the contact angle technique. An antifungal effect was observed, the mycelial growths (3·25-100%) and the synthesis of ochratoxin A (25·94-100%) were inhibited by the presence of the nanofibres. The results suggest that bioactive nanofibres hold promise for application to control toxigenic fungi.

Bactericidal and antioxidant effects of essential oils from Satureja montana L., Myristica fragrans H. and Cymbopogon flexuosus.

The extraction and characterization of the essential oils (EO) from Satureja montana L., Myristica fragrans H. and Cymbopogon flexuosus and the determination of their antibacterial and antioxidant activities were achieved. The EO were identified by gas chromatography/mass spectrometry and quantified by gas chromatography using a flame ionization detector. The antibacterial potential against Escherichia coli and Staphylococcus aureus was evaluated by cell susceptibility assays and by scanning electron microscopy. The antioxidant activity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl assay, by ß-carotene bleaching and by determining the reducing power. Borneol (36·18%), γ-terpineol (12·66%) and carvacrol (11·07%) were the principal components in the EO from S. montana, and sabinene (49·23%) and α-pinene (13·81%) were found in the EO from M. fragrans. Geranial (59·66%) and neral (38·98%) isomers were the only major components in the EO from C. flexuosus. The EO from S. montana was effective against E. coli, with minimum inhibitory and bactericidal concentrations (MIC and MBC) of 6·25 µl ml-1 , whereas bactericidal potential against both was observed for the EO from M. fragrans; MIC = 6·25 µl ml-1 for S. aureus and MBC = 12·5 µl ml-1 for E. coli. A significant protective role on lipid substrates in the ß-carotene bleaching assay was seen for the EO from S. montana and M. fragrans. Overall, such EO can be promising agents against pathogenic bacteria and for protecting biomolecules during oxidative stress.