For other uses of analog, see Analog (disambiguation).

In chemistry

Chemistry

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

, a structural analog (structural analogue), also known as chemical analog or simply analog, is a compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 having a structure similar to that of another one, but differing from it in respect of a certain component. It can differ in one or more atom

Atom

The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s, functional group

Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

s, or substructures, which are replaced with other atoms, groups, or substructures. A structural analog can be imagined to be formed, at least theoretically, from the other compound.

Despite a high chemical similarity, structural analogs are not necessarily functional analog

Functional analog

Functional analogs , are compounds that have similar physical, chemical, biochemical, or pharmacological properties. An example of a functional analog is morphine and heroin. Functional analogs are not necessarily also structural analogs with a similar chemical structure...

s and can have very different physical, chemical, biochemical, or pharmacological properties.

In drug development

Drug development

Drug development is a blanket term used to define the process of bringing a new drug to the market once a lead compound has been identified through the process of drug discovery...

 large series of structural analogs of an initial lead compound

Lead compound

A lead compound in drug discovery is a chemical compound that has pharmacological or biological activity and whose chemical structure is used as a starting point for chemical modifications in order to improve potency, selectivity, or pharmacokinetic parameters.Lead compounds are often found in...

 are created and tested as part of a structure-activity relationship

Structure-activity relationship

The structure–activity relationship is the relationship between the chemical or 3D structure of a molecule and its biological activity. The analysis of SAR enables the determination of the chemical groups responsible for evoking a target biological effect in the organism...

 study.

See also

• Derivative (chemistry)
  Derivative (chemistry)
  In chemistry, a derivative is a compound that is derived from a similar compound by some chemical or physical process. In the past it was also used to mean a compound that can be imagined to arise from another compound, if one atom is replaced with another atom or group of atoms, but modern...
  
  
• Homolog
  Homology (chemistry)
  In chemistry, homology refers to the appearance of homologues. A homologue is a compound belonging to a series of compounds differing from each other by a repeating unit, such as a methylene group, a peptide residue, etcetera....
  
  , a compound of a series differing only by repeated units
• Functional analog
  Functional analog
  Functional analogs , are compounds that have similar physical, chemical, biochemical, or pharmacological properties. An example of a functional analog is morphine and heroin. Functional analogs are not necessarily also structural analogs with a similar chemical structure...
  
  , compounds with similar physical, chemical, biochemical, or pharmacological properties
• Transition state analog