Extruded films of blended chitosan, low density polyethylene and ethylene acrylic acid.

The obtaining of chitosan extruded films was possible by using low density polyethylene (LDPE) as a matrix polymer and ethylene-acrylic acid copolymer as an adhesive, in order to ensure adhesion in the interphase of the immiscible polymers. The obtained blend films were resistant; however, a reduction in the mechanical resistance was observed as chitosan concentration increased. The thermal stability of the films showed a certain grade of interaction between polymers as seen in FTIR spectra. The antifungal activity of the extruded films was assessed against Aspergillus niger and high inhibition percentages were observed, which may be mainly attributed to barrier properties of the extruded films and the limited oxygen availability, resulting in the inability of the fungi to grow. A low adherence of fungal spores to the material surface was observed, mainly in areas with chitosan clumps, which can serve as starting points for material degradation.

Antibacterial and antifungal activities of some Mexican medicinal plants.

In Mexico about 4,000 plant species have some medicinal use. The aim of this work was to evaluate the antimicrobial activity of six Mexican medicinal plants against fungi and Gram-positive and Gram-negative bacteria. Methanolic extracts were prepared from the Mexican medicinal plants Amphypteringium adstrigens, Castella tortuosa, Coutarea latiflora, Ibervillea sonorae, Jatropha cuneata, and Selaginella lepidophylla. The antibacterial and antifungal activities of the plants were determined by the broth microdilution method and the radial growth inhibition assay, respectively. All Mexican plants tested showed antimicrobial activity. Among the six plant extracts analyzed, J. cuneata showed the highest growth-inhibitory activity against fungi, Gram-positive and Gram-negative bacteria (J. cuneata > A. adstrigens > C. latiflora > C. tortuosa > I. sonorae approximately S. lepidophylla). Shigella flexneri and Staphylococcus aureus were the most susceptible bacteria to plant extracts. Complete inhibition of S. flexneri growth was observed with J. cuneata methanolic extract at 90 microg/mL. This plant extract also showed the strongest antifungal activity against Fusarium verticillioides and Aspergillus niger. Our data suggest that the medicinal plants tested have important antimicrobial properties. This is the first report describing the antimicrobial activities of several of the Mexican medicinal plants used in this study.