Essential oils as antibacterial agents against food-borne pathogens: Are they really as useful as they are claimed to be?

Most studies evaluating the use of essential oils (EO) as antibacterial agents focus mainly on minimal inhibitory concentrations (MIC) rather than minimal bactericidal concentrations (MBC). In this work, we compared MICs and MBCs of EO from condiment plants commonly used in Mediterranean Europe, namely Origanum vulgare, Salvia lavandulaefolia, Salvia officinalis, Salvia sclarea and Rosmarinus officinalis, aiming to evaluate their application as disinfecting agents in minimally processed produce. Outbreaks-related pathogens such as Listeria monocytogenes, Pseudomonas aeruginosa and Yarrowia lipolytica were used. Results showed that all EO were able to reduce bacterial growth in all bacterial strains tested, particularly O. vulgare. However, fewer EO exhibited bactericidal activities, and were only effective against one or two bacterial strains, hence eliminating the possibility to use them as broad range disinfectants. Furthermore, the necessary concentrations were too high for food application. Hence, our work suggests the need to evaluate MBC rather than MIC and questions EO usefulness in controlling undesired microorganisms. Overall, and despite the large volume of data published on EO, results obtained were not very encouraging for a realistic application on produce and question the viability of EOs as disinfecting agents in food.

Legume seeds and colorectal cancer revisited: Protease inhibitors reduce MMP-9 activity and colon cancer cell migration.

MMP-9 activity is strongly related to cancer growth and metastization. This study aimed at assessing the inhibitory potential of the major seed protein fractions from eight selected legume species towards MMP-9 activity in colon carcinoma cells. Albumin and globulin fractions were screened for MMP-9 inhibitors, using a fluorometric assay and gelatin zymography. Their effect on HT29 cell proliferation and cell migration was tested, as well as on the corresponding intrinsic cellular MMP-9 activities. Seed proteins include potent inhibitors of MMP-9, particularly low molecular mass proteins. Their effectiveness differs greatly among species, with a positive correlation detected between their inhibitory activity and the reduction in cell migration. Lupin seeds contain the most efficient MMP-9 inhibitors of all legume seeds analyzed, inhibiting both gelatinases and HT29 migration and growth, while pea seeds showed no effect. Results reveal legume protein MMPIs as novel metalloproteinase inhibitors with possible pharmacological interest. This may be important for selecting leguminous species with potential use in anti-cancer diets.

Analytical results for long-time behavior in anomalous diffusion.

We investigate through a generalized Langevin formalism the phenomenon of anomalous diffusion for asymptotic times, and we generalized the concept of the diffusion exponent. A method is proposed to obtain the diffusion coefficient analytically through the introduction of a time scaling factor λ. We obtain as well an exact expression for λ for all kinds of diffusion. Moreover, we show that λ is a universal parameter determined by the diffusion exponent. The results are then compared with numerical calculations and very good agreement is observed. The method is general and may be applied to many types of stochastic problem.