Glucuronidation characteristics

Oleuropein, a conjugate of hydroxytyrosol (3,4-dihydroxybenzyl alcohol), is a characteristic but very variable component of olives and olive oil. After consumption of 25 ml virgin olive oil, hydroxytyrosol, 3-(9-methylhydroxytyrosol (homovanillyl alcohol), and homovanillic acid increase in plasma, as conjugates, predominantly glucuronide ° Oleuropein may be deconjugated by the gut microflora. 

Table 1. Characteristic Oleanene Glucuronides (OGs) Isolated from... 

Various other oleanene glucuronides having a characteristic functional group were also tested and the structure-anti-complementary activity... 

When stereoisomers are biotransformed by a variety of pathways, differences in the susceptibility of the separate isomers to these pathways result in stereoselectivity for their metabolite patterns. For example, 5-warfarin is oxidized to form primarily 7-hydroxy-5-warfarin, whereas the R enantiomer predominantly undergoes hydroxylation in the 6-position.f Oxazepam glucuronidation is 3-3.4 times higher for the S isomer compared to the R isomer in man and dogs. Biotransformation may generate an additional chiral center in the drug structure and result in diastereo-meric metabolites with markedly different disposition characteristics. 

Diflunisal is a fluorinated salicyhc acid derivative, which is absorbed unchanged from the gastrointestinal tract, reaching peak concentrations after about 2 hours, and is metabolized by glucuronidation (1). Its adverse effects and other characteristics are those of aspirin, although gastrointestinal haemorrhage may be less common (2). 

The level and activity of specific enzymes involved in biotransformation can differ depending on the species, strain, age, and sex of the test animal. For example, cats cannot carry out glucuronidation reactions, newborn rats have relatively low cytochrome P450 activity, and male rats are more sensitive to carbon tetrachloride toxicity than female rats. These differences are important to consider when interpreting the results from toxicological studies. The observation that age, sex, and genetics can significantly influence biotransformation reactions in animals raises the question of whether these characteristics also affect the biotransformation capacity of humans. 

The last FAB spectrum. Figure 12, is that of hydroxyhexamethyl melamine glucuronide measured with a thioglycerol matrix. The protonated molecular ion is observed, as well as the class characteristic ion (M+H-194) of mass 20. When this analysis was run from a glyceroi matrix, (M-H) ions were desorbed in greater abundance than (M+H) ions. 

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