Glucuronic acid occurrence

Table II lists derivatives of D-glucuronic acid which have been obtained by catalytic oxidation. A ready preparation of 3-0-methyl-D-glucuronic acid is by the oxidation of l,2-0-isopropylidene-3-0-methyl-D-gluco-furanose and subsequent hydrolysis of the product." 4-0-Methyl-D-glucuronic acid, a compound of considerable interest because of its occurrence as a fundamental unit in hemicelluloses" and polysaccharides," cannot be obtained by the simple catalytic oxidation of methyl 4-0-methyl-D-glucopyranoside. f...

Methyl ether groups are commonly encountered in plant polysaccharides, specially those that contain glucuronic acid. In animals they appear to be much less widespread, though small amounts of methyl ether could easily be overlooked. Among the fungi, instances are known of their occurrence, for example as 3-OMe-mannosyl residues in the walls of the spherules (sporangia) of Coccidioides immitis, but they are not particularly frequent. 

Triterpenoid Saponins. A unique occurrence of triterpenoid saponins in a species from the Solanales was reported on two constituents of Cestrum parqui L Herit. leaves (Abdel-Gwad et al. 1997). These compounds were characterized by the aglycone oleanolic acid 3 30-linked to a trioside composed of (i) two glucose units and one xylose and (ii) glucuronic acid, rhamnose, and glucose. 

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