Lipophilic molecules, enhancement

In contrast, there are less experimental data available for aliphatic series. Fluori-nation lowers lipophilicity and enhances the hydrophobicity. However, other factors, like strong hydrogen bonds or the enhancement of the dipolar moment, may lower the hydrophobicity and render the molecule more soluble or make its penetration easier. 

It has been a basic principle that one fluorine atom or trifluoromethyl group in a biologically active molecule enhances its lipophilicity. Smart3 argues that this rule holds only for fluorinated aromatics and fluorine adjacent to 7r-bonded systems. 

Thermal dependence of the flux of the four permeants (butanol, octanol, hydrocortisone and ARA-A) showed the three more lipophilic molecules exhibited large increases in permeability as the temperature of hairless mouse skin was raised from about 10 to 70°C. In contrast, no further enhancement of hydrocortisone flux was noted at temperatures above approximately 70°C. However, the less lipophilic solute, ARA-A, did not experience significant enhancement in permeability until higher termperatures above 37°C. Permeation of the molecules was either beginning to occur by alternate pathways or coming under dermis control. 

Most pharmaceuticals are hydrophilic and do not penetrate epithelial barriers at clinically useful rates. It has long been known that lipophilic molecules serve as permeability enhancers for such drugs.I12 13 This is... 

The most attractive possibility Is that nickel promotes the absorption of Fe(III) per se by enhancing Its complexatlon to a lipophilic molecule. Evidence shows that both active and passive transport mechanisms have roles In Iron absorption. 

First, we need to think about solubility. The two main categories are lipophilic and hydrophilic. Lipophilic molecules are those that prefer to be dissolved in fatty tissue. These will be molecules that are mostly nonpolar, just like fatty tissue. Lipo refers to lipids, which is another name for fats. Philic refers to -loving so lipophilic means fat-loving. We could also call these hydrophobic molecules as they are nonpolar and they are water-hating . Hydrophilic means water-loving and these will be polar molecules, molecules with plenty of -OH and -NH groups that enhance H-bonding, or ionic substances. 

OP nerve agents, which are small lipophilic molecules, can easily penetrate the BBB by free diffusion and thereby inhibit AChE in the CNS (Mercey et al., 2012). Increased BBB permeability by OP nerve agents or other ChE inhibitors may lead to their enhanced entry into the brain, resulting in greater AChE inhibition and possibly resulting in subsequent maintenance of seizures and aggravation of their pathological consequences, such as edema and neuronal loss in certain brain structures. Evidently, increased BBB permeability may facilitate the entry of an antidote (oxime class) to the brain, which otherwise has limited access because of the BBB. 

Cell membranes are lipophilic and designed to be barriers against large anionic molecules, although there is a natural mechanism for intercellular transport of anionic oligonucleotides. In order to enhance membrane transport, antisense oligonucleotides are frequentiy modified by covalent attachment of carrier molecules or lipophilic groups. 

Because skin exhibits many of the properties of a lipid membrane, dermal penetration can often be enhanced by increasing a molecule s lipophilicity. Preparation of an ester of an alcohol is often used for this purpose since this stratagem simultaneously time covers a hydrophilic group and provides a hydrophobic moiety the ready cleavage of this function by the ubiquitous esterase enzymes assures availability of the parent drug molecule. Thus acylation of the primary alcohol in flucinolone (65) with propionyl chloride affords procinonide (66) the same transform... 

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