Class 2 receptors, concepts

In the technique of post hoc design, a set of descriptors are built up by examination of a set of compounds active at a particular receptor family or sub-class. Normally, the set of drugs would be from a commercial database such as MDDR or the Merck Index, etc. and the descriptors would usually be substructural fragment or key based. One example would be the GPCR-PA+ sub-class referred to above, where BCUT descriptors have been used to aid the design of a focused library of aroimd 2000 compoimds based on 8 scaffolds. Libraries have also been constructed based on peptidomimetic principles as well as on the concepts of privileged structures. ... 

If a patient is diabetic, ACE-I will be advised, because it may reduce new-onset of HE and protect against nephropathy. The use of an Angiotensin-II receptor blocker (ARB) is also a good choice for these diabetic patients and for their nephropathy. The basic concept of drug selection will be combination therapy using different classes such as ACE-I and... 

An important concept to appreciate regarding receptors is that they are not static, stand-alone components of a cell. On the contrary, they are an integral part of the overall homeostatic balance of the body. For example, receptors can become desensitized upon continuous exposure to an agonist. When desensitization involves a specific class of agonists it is referred to as homologous desensitization. If response is reduced by disparate classes of drugs, the term heterologous desensitization is applied. 

Sweet taste is produced by a wide variety of compounds. SHAL-LENBERGER and ACREE (6) regard an acid/base system (AH/B-System) as the shared structural element. This system must satisfy certain steric conditions and can interact with a complementary system of a receptor via 2 hydrogen bonds (Fig. 1). KIER (7) expanded this model by assuming an additional interaction witfi an apolar group X in a suitable position (Fig. 1). Both models are applicable to compounds with great variations in structure. There are no similar comprehensive concepts for bitter compounds which can also occur in the most varying chemical classes. 

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