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CHE 310 Lecture 15: CHE310Toxicants

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26 Feb 2017

School

Stony Brook University

Department

Course

Professor

Katherine Aubrecht

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Document Summary

Ko(cid:449) is a measure of the relati(cid:448)e (cid:858)hydropho(cid:271)i(cid:272)ity(cid:859) of a mole(cid:272)ule. If a pollutant was more h20 soluble (low log kw) it would be able to leave the system easily (low bio concentration factor) The more non-polar the higher the kow. A molecule which has a large kow would not leave the system easily and therefore accumulate making it more toxic. Persistent organic pollutants (pops) are chemical substances that persist in the environment, bioaccumulate through the food web, and pose a risk of causing adverse effects to human health and the environment. They are resistant to photolytic, chemical or biological degradation. A pollutant is defined as persistent if there are nor processes (such as hydrolysis, photochemical reactions, microbial reactions) occurring in the environment that can convert the pollutant into less toxic species over a time of years. Examples of pops (12 of them) include: hexachlorobenzene, ddt,

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Related Questions

Please help with questions 1-5. Thank you!

46 Experiment 8: Determination of Kow the lipid and As stated, for a drug to pass from the small intestine to the bloodstream, it must cross bilayer, move through the aqueous cell, cross the other side of the spherical lipid bilayer. then exit into the aqueous blood stream. The drug must thus show some affinity tor aqueous and organic phases The partition coefficient (P) is an equilibrium constant for a process in which a solute is the distribution of partitioned between two phases. In medicine, this value is useful in estimating drugs within the body. Hydrophobic drugs with high partition coefficients are preferentially distributed to hydrophobic areas (such as fat tissues) while hydrophilic drugs with low partition coefficients prefer hydrophilic regions (such as blood serum). Partition coefficients can also be useful in predicting metabolic stability, as extremely hydrophobic drugs are often metabolized to more polar compounds to increase their water solubility for more effective urinary excretion. Given the complexity of cells, it is very difficult to directly measure partitioning of a compound between the aqueous and lipid components of a cell, particularly if evaluating the tens of thousands of compounds that might be investigated in a new drug development program. Hence, a simpler model system can be used in which 1-octanol serves as a mimic of the amphiphilic membrane lipid molecules, and water as the aqueous component. (In some cases, buffer solutions at particular pH values are used to better mimic cellular conditions). The partition coefficient P is often denoted as Kom, which specifically describes the degree to which a drug prefers octanol (o) or water (w). Knowing the Kow of a drug is crucial to predicting its pharmokinetic properties (i.e what the body will do to the drug). For convenience, a logKo value is more typically reported than Kow itself. Drugloctanol ow[Drug water In this experiment, we will investigate the ability of several drugs to move between aqueous and organic phases. These drugs are sulfanilamide (an antibiotic), phenacetin (an analgesic), acetaminophen (an analgesic), and caffeine (a stimulant) (Figure 3). We will determine logK by measuring the equilibrium concentrations of the drug in the aqueous and organic phases using UV-Vis spectroscopy NH2 HN Sulfanilamide Phenacetin Caffeine Figure 3: Structures of the drugs for which we will determine a partition coefficient