Glucuronide linkage

Specimen preparation for cannabinoid testing frequently includes a hydrolysis step to free cannabinoids from their glucuronide conjugates. Most GC/MS confirmation procedures in urine measure total THCCOOH following either an enzymatic hydrolysis with //-glucuronidase, or more commonly, an alkaline hydrolysis with sodium hydroxide. Alkaline hydrolysis appears to efficiently hydrolyze the ester THCCOOH glucuronide linkage. 

Details of the selective cleavage of o-glucuronidic linkages in saponins have been published (see Vol. 10, p. 117). A modified procedure for determining the sites of attachment of hexuronic acid residues in methylated acidic polysaccharides by base-catalysed degradation has been modelled on experiments with the methylated aldobiouronic acid derivative (430), which eliminated methyl 2,3,4-tri-O-methyl-p-D-glucopyranoside (89%) on treatment with sodium methylsulphinyl-methanide in DMSO at room temperature. When this procedure is applied to... 

A new method for selectively cleaving the D-glucuronidic linkages of saponins is based on oxidative decarboxylation of per-C>-methylated derivatives with lead tetra-acetate in benzene, followed by release of the aglycone with base (Scheme... 

Thus, the results of degradation studies have established the P-(i - -3)-glucuronidic linkage, and suggested a linkage at C-4 of the glucuronic moiety. 

Animals. 98.5-100% of 14C was excreted within 7 days. The major metabolic routes were deethylation of the 4-ethoxy group, cleavage of the carbamate linkage, acetylation, and finally formation of the glucuronide and sulfate conjugates... 

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