ABSTRACT
Interspecies differences in glycosidation potential in mammalian tissues represent a factor contributing to ambiguity when endobiotic and/or xenobiotic metabolic pathways are extrapolated from animals to man. Using the TLC/autoradiographic technique, we conducted an in vitro investigation involving mouse, rat, monkey, as well as human liver and kidney microsomes to evaluate their glycoconjugation potential towards (3)H-labeled, purine-derived selective inhibitors of cyclin-dependent kinases such as olomoucine, bohemine, roscovitine, 6-(2-hydroxybenzyl)amino-2-(1-hydroxymethyl-2-methylpropyl)amino-9-isopropylpurine (compound A-4), and 6-(3-hydroxybenzyl)amino-2-[(1(R/S)-hydroxymethyl)propyl]amino-9-isopropylpurine (compound A-5) as aglycones. Principally, this study confirmed the aliphatic hydroxyl group of olomoucine-type inhibitors as a relatively suitable target for glucuronide, glucoside, xyloside, galactoside, and/or N-acetylaminoglucoside conjugation. Of the tissues examined, only the mouse microsomes were able to perform glucosidation and galactosidation reactions with the aglycones. On the other hand, monkey microsomes were superior to the mouse microsomes in a variety of glucuronide conjugates produced with compounds A-4 and A-5.
Subject(s)
Cyclin-Dependent Kinases/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Glycosides/metabolism , Microsomes/enzymology , Purines/pharmacology , Animals , Chromatography, Thin Layer , Enzyme Inhibitors/chemical synthesis , Glycosylation , Humans , In Vitro Techniques , Kidney/metabolism , Kinetin , Macaca mulatta , Magnetic Resonance Spectroscopy , Mass Spectrometry , Mice , Microsomes/drug effects , Microsomes, Liver/metabolism , Purines/chemical synthesis , Rats , Species SpecificityABSTRACT
In vitro subcellular and cellular systems have important and irreplaceable roles in the metabolic investigations that precede the development of new potential drugs. Of these model systems, tissue slices are probably the nearest to in vivo conditions. From the experimental and complexity points of view, perfused organs lie midway between tissue slices and whole organism. Preparation and working with liver slices is quick and easy, and, excess material can be cryopreserved and stored untill the next experiment. Slices can be prepared from a wide variety of organs and it is possible to co-incubate them. Another important feature is the possibility of interspecies comparison of slices. Different experiments can be run both in the short-term as well as long-term incubations. Each in vitro system has an important place for example, in the development of new medicaments. It is therefore important to compare and supplement experimental results from different in vitro systems when extrapolating to in vivo situations is done.
