Physical-Chemical Factors and Biological Activities

In the recent past, receptors and drug-reeeptor interaetions theories have highlighted the importance of physical and chemical characteristics with regard to drug action. Such salient features may include partition coefficients, solubility, degree of ionization, isosterism and bio-isosterism, surface activity, thermodynamic activity, intramolecular and intermolecular forces, redox potentials, stereochemisty and interatomic distances between various funetional groups. 

Therefore, a ereative medicinal chemist should ponder over the intricacies, complexities and legitimate presenee of eaeh funetional moiety to the overall physical chemical properties of the target-drug molecule with a view to arrive at or design safer, better and efficacious medicinal agents. Nevertheless, sueh eritieal studies have to be earried out in a rather methodical and systematic manner 

It would be worthwhile to look into the physical and chemical aspects of the drug separately and an attempt made to establish the relation of such properties to biological activities. 

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Leaching of chemicals from complex materials or matrices is a complicated phenomenon in which many factors may influence the release of the specific organic compounds and inorganic ions. Important factors include major element chemistry, pH, redox, complexation, liquid to solid ratio, contact time, and biological activity. To describe fully the leaching of SWMs/COMs under field conditions, a battery of leaching tests was specifically designed to simulate various physical and chemical release mechanisms. 

Weathering rates are dependent on a number of factors that can be classified as either intrinsic or extrinsic to a specific mineral (White and Brantley, 2003). Intrinsic properties are physical or chemical characteristics such as mineral composition, surface area, and defect densities. If intrinsic properties dominate weathering, such characteristics should be transferable between environments, e.g., laboratory and field rates of the same mineral should be comparable. Extrinsic feamres reflect environmental conditions external to the silicate phase that impact chemical weathering such as solution composition, climate, and biological activity. These processes are dependent on external environmental conditions that are difficult to recreate fully under laboratory simulations. 

The critical factor for biological activity is the 3D spatial arrangement of these chemical and physical properties. The result of a 3D QSAR analysis is typically supplied as a 3D graphics image superimposed on a molecule of the data set. The images represent the coefficients of a pseudo-regression equation with the original variables, here as locations in the 3D space. 

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