Bioactive compounds, such as antimicrobial peptides (AMPs), have increasingly been used recently to counteract the rapidly increasing incidence of bacterial resistance to usual antibiotics and chemotherapeutics. In humans, endogenous AMPs are part of the immune system and act against pathogens. Defensins compose a class of AMPs that have activity against gram-positive and-negative bacteria, viruses, and fungi. For some, antitumour activity has also been reported. Such characteristics indicate that they represent a potential new class of therapeutic agents against microorganisms, including multidrug resistant pathogens. However, pH and enzymatic degradation and variable tissue distribution of these compounds limit their clinical application. New technologies and different methods have been developed to overcome these limitations and increase their half-life, such as cyclization, lipidation, design of peptidomimetics, synthesis of hybrid peptides, and use of nanocarriers. The objective of this review was to analyse current applications of defensins as antimicrobial agents and their mechanism of action. Moreover, new technologies and methods for stabilizing defensins are discussed.

Human neutrophil peptides (HNPs, alpha-defensins) are a group of six defensins being considered as new antimicrobial drugs because of their multifunctional efficiency against bacteria, viruses and fungi. Regardless of the unique biological properties, alphadefensins are unstable compounds and their activity depends on many physical and chemical factors as well as on the kind of the used cultivation media. This leads to research difficulties and obstructions in their therapeutic application. The purpose of this study was to determine antibacterial activity of alpha-defensin 2 dissolved in pharmacopeia buffers and in parallel to develop selective and accurate analytical tests for identification and assay of alpha-defensin 2 in the course of study. The antibacterial effect of alpha-defensin 2 was determined against the strain Escherichia coli (ATCC 25922). It was found that 10 mg/L of Human neutrophil peptide-2 (HNP-2, alpha-defensin 2) dissolved in pH 9.0 buffer caused 90% inhibition of the bacterial respiratory activity. This buffer was considered as a suitable environment for deploying the antibacterial activity of the alpha-defensin. A selective MS analysis method for the identification of alpha-defensin 2 in sample mixtures was developed. Also, the HPLC method with alternative selectivity was elaborated for identification and assay of mixtures containing alpha-defensin 2 and aminoacids in Mueller Hinton broth. The procedure includes development of system suitability test determination.

Aim:The aim of this research study was to develop a simple, rapid, precise, accurate and economical RP-HPLC method, with a simple mobile phase for the identification and determination of the antimicrobial peptide α-defensin-2. Materials and Methods: Separation was carried out at 25°C, using column Luna 5U (C 18 , 250x4.6, 5 μm) with mobile phase consisting of acetonitrile: water (40: 60 v/v). The detector was set at 210 nm. The flow rate was 1.2 ml/min and injection volume was 20 μl. Results: The developed method was validated as per ICH guidelines and the kinetic behavior of α-defensin 2 was studied in respect of different pH. Conclusion: The obtained data can serve for creating an in vivo monitoring program and quality control for different studies and preparations.

dangerous' products, the analysis showed that 37% of these reagents present a high to very high risk, such as formaldehyde, 42% have a medium risk such as nitric acid and 21% pose a low to very low risk such as acetone.Our second aim was to reduce risks, so we have proposed preventive measures such as the use of personal protective equipment (mask, gloves) and collective (hoods). The levels of risk have significantly decreased: 82% of the reagents with a very low risk and 12% have a medium risk. The products that have kept a very high severity are used rarely and in small quantities. Conclusion Our results concord with the literature. We have demonstrated that the level of severity of reagent is manageable by acting on two risk factors: the respect of the safety measure of each chemical and the exposure of the operator to the operations carried out. REFERENCE AND/OR ACKNOWLEDGEMENTS1. Abecassis P. La méthode Oper@ pour l'évaluation chiffrée du risque chimique.