Biological activity

In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or pharmacophore but can be modified by the other constituents. Among the various properties of chemical compounds, pharmacological/biological activity plays a crucial role since it suggests uses of the compounds in the medical applications. However, chemical compounds may show some adverse and toxic effects which may prevent their use in medical practice. Biological activity is usually measured by a bioassay and the activity is generally dosage-dependent, which is investigated via dose-response curves. Further, it is common to have effects ranging from beneficial to adverse for one substance when going from low to high doses. Activity depends critically on fulfillment of the ADME criteria. To be an effective drug, a compound not only must be active against a target, but also possess the appropriate ADME (Absorption, Distribution, Metabolism, and Excretion) properties necessary to make it suitable for use as a drug. Because of the costs of the measurement, biological activities are often predicted with computational methods, so-called QSAR models. Bioactivity is a key property that promotes osseointegration for bonding and better stability of dental implants. Bioglass coatings represent high surface area and reactivity leading to an effective interaction of the coating material and surrounding bone tissues. In the biological environment, the formation of a layer of carbonated hydroxyapatite (CHA) initiates bonding to the bone tissues. The bioglass surface coating undergoes leaching/exchange of ions, dissolution of glass, and formation of the HA layer that promotes cellular response of tissues. The high specific surface area of bioactive glasses is likely to induce quicker solubility of the material, availability of ions in the surrounding area, and enhanced protein adsorption ability.