Natural products immunomodulation

Enzymatic desymmetrization of prochiral or meso-alcohols to yield enantiopure building blocks is a powerful tool in the synthesis of natural products. For example, a synthesis ofconagenin, an immunomodulator isolated from a Streptomyces, involved two enzymatic desymmetrizations [149]. The syn-syn triad of the add moiety was prepared via a stereoselective acylation of a meso-diol, whereas the amine fragment was obtained by the PLE-catalyzed hydrolysis of a prochiral malonate (Figure 6.56). 

The inhibitory effects of berbamine and ISO natural products on the cytotoxic activity of polymorphonuclear leukocytes (PMN) was investigated. The research employed the effects of natural products on the PMN activation by the antitumor immunomodulator TAK (a linear P-1,3-D-glucan from Alcaligenes faecalis var. myxogenes) using a PMN cytotoxicity assay system. Berbamine was found to inhibit the activation of PMN activation by TAK, showing an IDJ0 33 pg/ml. From this, and related studies, it was postulated that berbamine may impair the NADPH oxidase system in the plasma membrane of PMN [199]. 

In addition, the following are examples of other natural products identified conformational studies of modified glycopeptide related to the cell wall pep-tidoglycan of bacterial cell walls were correlated with immunomodulating activities. The structure of the OPS of the LPS of Hafnia alvei strain PCM1546 was characterised fully as Gal(pi-3)GalNAc(pi-6) [3-0-Ac]Glc(al-3)GlcA(al-... 

The sterols and sterolins in rice bran are potent immunomodulators. The best response was obtained with a 100 1 sterol/sterolin mixture that demonstrated T-cell proliferation from 20% to 920% and active cell antigens after four weeks in human subjects (Bouic et al, 1996). Another in vitro experimental study with sterol/sterolins, demonstrated a significant increase in cytokinines, interleukin-2 and y-interferon between 17% and 41 % in addition to an increase in natural killer cell activity. These experiments (Bouic et al, 1996) prove that sterol/sterolins are potent immunomodulators with important implications for the treatment of immune dysfunction. Rice bran products are excellent dietary supplements for the improvement of immune function. It is probable that the effects of rice bran on diabetes, CVD and cancer all result from improved immune function. 

EPS from LAB have become industrially attractive compounds due to then-great potential economic applications in the food industry as natural and safe food additives for improving smoothness, rheological properties, texture, mouthfeel, stability, and water retention of the final (mainly dairy) food products (Table 11.2). EPS are also important in the clinical and pharmaceutical industries. More recently, it has been suggested that these biopolymers display health-promoting properties such as antiulcer, antitumor, cholesterol-lowering, or immunomodulating activities, and that they could act as prebiotics [292, 293]. 

Gallois, M., H. J. Rothkotter, M. Bailey, C.R. Stokes and I.P. Oswald, 2009. Natural alternatives to in-feed antibiotics in pig production can immunomodulators play a role Animal 3, 1644-1661. 

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