Plants 2-keto-3-deoxy acids

Figure 20 Sialic acids include NeuSAc, NeuSGc, and KDN. KDO is a closely related eight-carbon keto-deoxy acid that is found in several types of prokaryotes and plants.

Reports of sialic acids in plants exist in the literature (Mayer et al. 1964, Onodera et al. 1966), but the analytical methods employed were insufficient to exclude other compounds such as 2-keto-3-deoxy acids noted earlier in this chapter. Several investigations produced negative results, although a reaction in the periodic acid/thiobarbituric acid assay was obtained. The compounds in question gave no colour in the direct Ehrlich, orcinol/Fe and resorcinol assays for sialic acids (Gielen 1968, Cabezas 1968, 1973, CABEZAsand Feo 1969, Unger 1981). 

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