Antibacterial activity of free or encapsulated selected phenylpropanoids against Escherichia coli and Staphylococcus epidermidis.

AIMS: Antibacterial activities of phenylpropenes (PPs) (eugenol, isoeugenol, estragole and trans-anethole) and hydroxycinnamic acids (HCAs) (p-coumaric, caffeic and ferulic acids) were assessed against Escherichia coli and Staphylococcus epidermidis. Effect of cyclodextrin and liposome encapsulation on the PPs activity was also evaluated. METHODS AND RESULTS: All PPs inhibited the bacterial growth in the hundred micromolar range, while HCAs did not, as determined by broth macrodilution. Anethole and estragole showed a higher efficiency than eugenol and isoeugenol, and E. coli was more susceptible than S. epidermidis. Hydroxypropyl-ß-cyclodextrin/PP complexes and anethole-loaded Lipoid S100-liposomes were prepared by freeze-drying and ethanol injection respectively. Both formulations were substantially less active than free PPs. For instance, E. coli growth inhibition was about 14% for all HP-ß-CD/PP complexes evaluated at MIC50 values of free PPs (P < 0·05), and about 12% for liposomal anethole evaluated at minimal bactericidal concentration value of free anethole (P < 0·05). CONCLUSIONS: Hydrophobicity appears to be crucial for PPs antibacterial activity. Encapsulation in cyclodextrin and liposome seems to retain the PPs preventing their interaction with bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights the structural features of simple phenylpropanoids related to their antibacterial activity. The limitations of conventional encapsulation systems on the activity of PPs should be considered in future applications.

Retention of aroma compounds from Mentha piperita essential oil by cyclodextrins and crosslinked cyclodextrin polymers.

In this paper, the controlled release of aroma compounds from cyclodextrins (CDs) and CD polymers was studied by multiple headspace extraction (MHE) experiments. Mentha piperita essential oil was obtained by Soxhlet extraction and identification of the major compounds was performed by GC-MS analysis. Menthol, menthone, pulegone and eucalyptol were identified as the major components. Retention of standard compounds in the presence of different CDs and CD polymers has been realised by static headspace gas chromatography (SH-GC) at 25 °C in the aqueous or gaseous phase. Stability constants for standard compounds and for compounds in essential oil have been also determined with monomeric CD derivatives. The obtained results indicated the formation of a 1:1 inclusion complex for all the studied compounds. Molecular modelling was used to investigate the complementarities between host and guest. This study showed that ß-CDs were the most versatile CDs and that ß-CD polymers could perform the controlled release of aroma compounds.

Solubilisation of chlorinated solvents by cyclodextrin derivatives: a study by static headspace gas chromatography and molecular modelling.

The capacity of alpha-cyclodextrin (alpha-CD) and four beta-cyclodextrins (beta-CDs) in reducing the volatility of volatile organic compounds (VOCs) and particularly carbon tetrachloride (CT), chloroform (TCM) and dichloromethane (DCM) is investigated by using static headspace gas chromatography (HSGC). The experiments allowed the determination of Henry's law constant (H(c)) in absence and in presence of cyclodextrins (CDs). The use of CDs may lead to a reduction of 95% of the Henry's law constant for some VOCs. The association constants of the inclusion complexes formed between CDs and the three guests are determined using a new method involving an algorithmic treatment bringing the shortening of experimental time required for the determination of the stability constant. The complementarities of the host and the guest are investigated by molecular modelling. The complexation energies obtained are in good agreement with the experimental formation constants. Furthermore, this study shows the effectiveness of CDs in trapping pollutants and reducing their volatility in the viewpoint of pollution prevention.

[Reduction of the volatility of volatile organic compounds with cyclodextrins: application to their capture]. / Réduction de la volatilité des composés organiques Volatils par les cyclodextrines. Application à leur piégeage.

The interactions existing between beta-cyclodextrin, hydroxypropyl-beta-cyclodextrin and six volatile organic compounds (VOC) were studied and used for capture of such pollutants. The reduction of volatility for these VOC appeared to be equivalent for the two kinds of cyclodextrins at equal concentrations, while a higher solubility conferred higher efficiency to hydroxypropyl-beta-cyclodextrin. The use of such cyclodextrins in traps allowed a two-fold increase in VOC capture compared with genuine water. Application of this process to an industrial site showed its efficacity qualitatively while several optimization procedure are needed to achieve quantitative efficacy.