Glucans fungal

Some studies have evaluated the effects of polysaccharides in some physiological responses. Lindstrom et al. studied the effect of four polysaccharides, namely sclero-glucan (fungal exopolysaccharide), xanthan gum, gellan, and native dextran on plasma lipids and caecal formation of short-chain fatty acids (SCFA) in mice. Results showed... 

Curdlan possesses anti-tumour activity similar to that shown by fungal (1-D-glucans, a property which appears to be related to the ability to form triple helices. 

It may be that this fact was associated with the rather complex composition of fungal mycelium, consisting of chitin enclosed in a glucan matrix (Bowman, Free, 2006). Therefore, mature saprophyte mycelium are completely covered by difficult-soluble glucans and the fraction of chitin in the apical cell wall is not sufficient. As such, we supposed that these cationic isoforms bound with another major component of the fungi... 

Intrinsic (natural, innate) resistance. In one form of intrinsic resistance, the fungal cell wall (see Chapter 2) is considered to present a barrier to exclude or, more likely, to reduce the penetration by biocide molecules. The evidence to date is sketchy but the available information tentatively links cell wall glucan, wall thickness and consequent relative porosity to the sensitivity of Saccharomyces cerevisiae to chlorhexidine. 

IV. PARASITISM. Lysis by hydrolytic enzymes excreted by microorganisms is a well-known feature of mycoparasitism. Chitinase and P-l,3 glucanase (laminarase) are particularly important enzymes secreted by fungal mycoparasites capable of degrading the fungal cell wall components, chitin, and P-1,3 glucan (131-134). 

Figure 6 Detail of the interface space (IN) between the fungal wall (U) of Glomuf versiforvte and the host membrane of leek (PL), as seen by electron microscopy. Xylo-glucan molecules are revealed by using a specific antibody and colloidal gold granules. P, host cell F, fungus, X 30,000.

The echinocandins have a unique target for their antifungal activity—specifically, (5-1,3-glucan synthase, an enzyme that produces an important component of the fungal wall. Caspofungin is currently the only product of this class that is FDA approved it is indicated for treatment of IA refractory... 

Yoshitomi H, Sakaguchi N, Kobayashi K, et al. A role for fungal fi-glucans and their receptor Dectin-1 in the induction of autoimmune arthritis in genetically susceptible mice. J Exp Med 2005 201(6) 949-960. 

Deoxymulundo-candin (158) Echinocandin- type antifungal antibiotic Aminocandin (NXL-201, IP960, HMR-3270)(159) Antifungal (Candida sp. infections) Targets the glucan in fungal cell walls Phase I Novexel 825-827... 

It is noteworthy that most of the chemical shift values for all three polymers may be closely approximated ( ) by calculations based on data for monomeric reference compounds. These findings illustrate, therefore, the general validity of studies on low molecular weight model compounds for einalysis of spectra of carbohydrate polymers. Many examples of equally satisfactory comparisons of this kind are to be found in studies on other polysaccharides (11,23). These polymers include glucans (l6), mannans (2k, 2 ), limit dextrins (26), lichenin (2j), agarose (28) and various polysaccharides of fungal and microbial orgins (e.g., 7,8,29-31). Observed departures from expectation have been attributed to specific conformational influences ( 8). 

Pharmacology Micafungin is a semisynthetic lipopeptide (echinocandin) synthesized by a chemical modification of a fermentation product of Coleophoma empetri F-11899. Micafungin inhibits the synthesis of 1,3- -D-glucan, an essential component of fungal cell walls, which is not present in mammalian cells. Pharmacokinetics ... 

Caspofungin is the first of a new class termed the echinocandins. It was approved in the US and in Europe in 2001. It shows activity against infections with Aspergillus and Candida, and works by inhibiting p(, 3)-D-Glucan of the fungal cell wall. Compared to amphotericin B, caspofungin seems to have a relatively low incidence of side-effects. 

Echinocandins act at the level of the fungal cell wall by inhibiting the synthesis of B(l-3)-glucan (Figure 48-1). This results in disruption of the fungal cell wall and cell death. 

Caspofungin Blocks 3-glucan synthase Prevents synthesis of fungal cell wall Fungicidal Candida sp also used in aspergillosis IV only duration, 11-15 h Toxicity Minor gastrointestinal effects, flushing Interactions Increases cyclosporine levels (avoid combination)... 

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