What is S9 liver fraction?
S9 fraction is a mixture of unfractionated microsomes and cytosol containing a wide variety of drug-metabolizing enzymes and is commonly used as a preferred test system in several in vitro ADME (Absorption, Distribution, Metabolism, and Excretion) studies investigating phase I and phase II metabolism of a drug compound …
What is a metabolic activation system?
The chemical conversion of a relatively benign substance into a more hazardous one by normal biochemical processes in cells and tissues.
What is microsomal fraction?
a collection of tiny subcellular particles, invisible with the light MICROSCOPE, that are produced during DIFFERENTIAL CENTRIFUGATION of eukaryotic cells. Under the ELECTRON MICROSCOPE, these microsomes can be seen to consist mainly of membranes and RIBOSOMES from the ENDOPLASMIC reticulum.
What is S9 activation?
The default metabolic activation system includes rat liver postmitochondrial (“S9”) fraction with appropriate cofactors, i.e., S9 mix. S9 fraction is usually prepared from male rats induced with Aroclor 1254 or phenobarbital/5,6-benzoflavone and is stored frozen at −80°C prior to use.
What enzymes are in S9?
Unlike liver microsomes, which contain only the endoplasmic reticulum subcellular fraction (containing most notably cytochrome P450’s or CYPs and Uridine 5′-diphospho-glucuronosyltransferase; UGTs), the S9 fractions further contain the cytosolic enzymes such as aldehyde oxidase, xanthine oxidase, sulfotransferases.
What are carcinogens?
A carcinogen is an agent with the capacity to cause cancer in humans. Carcinogens may be natural, such as aflatoxin, which is produced by a fungus and sometimes found on stored grains, or manmade, such as asbestos or tobacco smoke. Carcinogens work by interacting with a cell’s DNA and inducing genetic mutations.
Do microsomes produce enzymes?
Microsomal enzymes are typically found in the endoplasmic reticulum of hepatocytes. Microsomes are fragments of endoplasmic reticulum and attached ribosomes that are isolated together when homogenized cells are centrifuged.
What are the microsomal enzymes?
There are several microsomal enzymes, including flavin monooxygenases, cytochrome P450, NADPH cytochrome c reductase, UDP Glucoronosyl transferases (UGT), glutathione-S-transferases, epoxide hydrolases, etc. Cytochrome P450 and NADPH cytochrome c reductase are the two main enzymes in this system.
What is S9 mix in Ames test?
Preparation of rat liver S9 mix. After centrifugation of liver homogenate at 9000, the supernatant (S9) is used as a metabolizing system in the Ames test. S9 contains microsomes and cytosol and therefore all microsomal and cytosolic xenobiotic metabolizing enzymes.