Phytoalexins oligosaccharides

In 1997 Nicolaou et al. published the assembly of a heptasaccharide phytoalexin elicitor (HPE, 16) on a solid support (Schemes 5.2-5.4).29 This oligosaccharide... 

The phytoalexin elicitor (PE) family of /1-D-glucans (Fig. 5) was selected as a target because these oligosaccharides had been synthesized previously in solution48,49 and on the solid support.50,51 It was our intention to investigate not only the application of glycosyl phosphates to automated solid-phase synthesis, but also to compare our method to the previously described reports of PE syntheses. 

Nicolau, K. C., Winssinger, N., Pastor, J., and DeRoose, F. (1997) A general and highly efficient solid phase synthesis of oligosaccharides. Total synthesis of a heptasaccharide phytoalexin elicitor (HPE)../. Am. Chem. Soc. 119,449—450. 

Yamada, A., Shibuya, N., Kodama, O. and Akatsuka, T. 1993. Induction of phytoalexin formation in suspension-cultured rice cells by A/-acetylchito-oligosaccharides. Biosci. Biotech. Biochem. 57, 405-409... 

Co-mediation of oligosaccharides and MJ has been demonstrated in the rice system in the induction of phytoalexins [100]. Exogenously applied MJ to elicited cells increased production of momilactone A to levels higher than those elicited with AT-acetylchitoheptaose alone. In suspension-cultured cells of parsley the influence of MJ on elicitation using cell walls of Phytophtora megasperma (Pmg elicitor) and chitosan was demonstrated [101]. These results suggested MJ conditioned the parsley suspension cells in a time-dependent manner to become more responsive to elicitation. 

SCHEME 27. Steric hindrance-facilitated synthesis157 of phytoalexin-elicitor active oligosaccharide 149. 

R. Geurtsen, F. Cote, M. G. Hahn, and G.-J. Boons, Chemoselective glycosylation strategy for the convergent assembly of phytoalexin-elicitor active oligosaccharides and their photoreactive derivatives, /. Org. Chem., 64 (1999) 7828-7835. 

Hormonal action of oligosaccharides (10 examples). Some free oligosaccharides occur in some plants as a response to contamination, and elicit the production of phytoalexines, plant antibiotics against fungi. 

The second example is a solid-phase synthesis of a heptasaccharide phytoalexin elicitor. Here, attachment of the polymer was to the reducing end of the oligosaccharide. The structure was chosen as an example for the development of... 

Heptaglucoside from the cell wall of Phytophthora megasperma. This oligosaccharide, which stimu-iates phytoalexin synthesis in Glycine max, was isolated from acid digests of the fungal cell wall. [J.K.Sharp et al. J. Biol. Chem. 259(1984) 11321-11336]... 

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