Lipopolysaccharides structural principles

Structural Principles of Lipopolysaccharides and Biological Properties of Synthetic Partial Structures... 

Lipopolysaccharides form a class of macromolecules unique to Gramnegative bacteria. They are of great compositional and structural diversity, and yet, they are built up according to a common architectural principle. With few exceptions, lipopolysaccharides are biologically highly active substances. Lipopolysaccharides have been called endotoxins because of their toxic properties. Due to the antigenic properties which they confer to the surface of the bacterial cell, they are also termed O antigens. 

The present paper will describe the principles of lipopolysaccharide architecture, summarize analytical results concerning different regions of the molecule, and refer to synthetic approaches to partial structures. 

Lipid A is the endotoxic principle of Gram-negative bacteria lipopolysaccharide. Its structure varies between bacteria. Sepsis could equally also be classed as immunomodulatory. 

Adsorbents are used in medicine mainly for the treatment of acute poisoning, whereas other extracorporeal techniques based on physico-chemical principles, such as dialysis and ultrafiltration, currently have much wider clinical applications [1]. Nevertheless, there are medical conditions, such as acute inflammation, hepatic and multi-organ failure and sepsis, for which mortality rates have not improved in the last forty years. These conditions are usually associated with the presence of endotoxin - lipopolysaccharide (LPS) or inflammatory cytokines - molecules of peptide/protein nature [2]. Advantages of adsorption over other extracorporeal techniques include ability to adsorb high molecular mass (HMM) metabolites and toxins. Conventional adsorbents, however, have poor biocompatibility. They are used coated with a semipermeable membrane of a more biocompatible material to allow for a direct contact with blood. Respectively, ability of coated adsorbents to remove HMM solutes is dramatically reduced. In this paper, preliminary results on adsorption of LPS and one of the most common inflammatory cytokines, TNF-a, on uncoated porous polymers and activated carbons, are presented. The aim of this work is to estimate the potential of extracorporeal adsorption technique to remove these substances and to relate it to the porous structure of adsorbents. 

Another example of the special lipid classes present in M. tuberculosis is methylglucose lipopolysaccharides. Characterization and analysis of methylglucose lipopolysaccharides, with bacterial lipopolysaccharides in general, were extensively reviewed [13], in which a wide variety of MS-based apphcations that were implemented to the structural elucidation of lipopolysaccharides were covered. Special description given in the review was the tandem mass spectrometric methods and protocols for the analyses of lipid A, the endotoxic principle of lipopolysaccharides. It is advised that advanced readers should look for the details from this invaluable review article [13],... 

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