Question

2. Nonanoic acid is used in Canada as a food flavouring agent, and as an ingredient in natural health products and cosmetics (e.g. eye make-up). Given its potential for human exposure, you decide to test nonanoic acid in mice to understand its pharmacokinetics and pharmacodynamics. The compound shows some interesting pharmacokinetic behavior after direct delivery to the blood stream (intravenous CH administration). Levels decrease rapidly over the first 3 hours, but HO then appear to level off and even increase slightly (see the graph below) Nonanoic acid 100 5 2s Time (hr) a) Phase lIl enzymes can directly conjugate nonanoic acid once it enters the liver. Draw the structure of the nonanoic acid phase II metabolite. (1 pt) b) Knowing about toxicant metabolism and elimination, indicate why you think that levels of nonanoic acid fall and then at about 2.5-3 hrs seem to level off or increase slightly instead of dropping to zero. (3 pts)

Answer 1

The enzymes involved in Phase I reactions are primarily located in the endoplasmic reticulum of the liver cell, they are called microsomalenzymes. Phase II metabolism involves the introduction of a hydrophilic endogenous species, such as glucuronic acid or sulfate, to the drug molecule.