Isostere
Classical Isosteres are molecules or ions with the similar shape and often electronic properties. Many definitions are available.[1] but the term is usually employed in the context of bioactivity and drug development. Such biologically-active compounds containing an isostere is called a bioisostere. This is frequently used in drug design:[2] the bioisostere will still be recognized and accepted by the body, but its functions there will be altered as compared to the parent molecule.
History and additional definitions
Non-classical isosteres do not obey the above classifications, but they still produce similar biological effects in vivo. Non-classical isosteres may be made up of similar atoms, but their structures do not follow an easily definable set of rules.
The isostere concept was formulated by Irving Langmuir in 1919,[3] and later modified by Grimm. Hans Erlenmeyer extended the concept to biological systems in 1932.[4][5][6] Classical isosteres are defined as being atoms, ions and molecules that had identical outer shells of electrons, This definition has now been broadened to include groups that produce compounds that can sometimes have similar biological activities. Some evidence for the validity of this notion was the observation that some pairs, such as benzene and thiophene, thiophene and furan, and even benzene and pyridine, exhibited similarities in many physical and chemical properties.
Isosteres [7](Isometrics) is defined at constant volume in terms of the physical chemistry description for ideal and real gases. For a true graph of V(P,T), which requires plotting the three variables P (pressure), T (temperature), and V (volume), assuming the moles of gas is constant:
- isotherms are given by and appear as hyperbolas
- isobars are given by and appear as straight lines
- isosteres are given by and appear as straight lines.
References
- ↑ Richard Silverman, The Organic Chemistry of Drug Design and Drug Action, Second Edition, 2004
- ↑ Nathan Brown. Bioisosteres in Medicinal Chemistry. Wiley-VCH, 2012, p. 237. ISBN 978-3-527-33015-7
- ↑ Irving Langmuir. Isomorphism, isosterism and covalence. J. Am. Chem. Soc. 1919, 41, 1543-1559. doi:10.1021/ja02231a009
- ↑ Mukesh Doble, Anil Kumar Kruthiventi, Vilas Gajanan. Biotransformations and Bioprocesses. CRC Press, 2004, p. 60. ISBN 0-8247-4775-5
- ↑ H. Erlenmeyer, Ernst Willi: Zusammenhänge zwischen Konstitution und Wirkung bei Pyrazolonderivaten. In: Helvetica Chimica Acta. 18, 1935, S. 740, doi:10.1002/hlca.193501801101.
- ↑ Hans Erlenmeyer, Martin Leo: Über Pseudoatome. In: Helvetica Chimica Acta. 15, 1932, S. 1171, doi:10.1002/hlca.193201501132.
- ↑ Adamson, Arthur (1973). A textbook of Physical Chemistry. The United State of America: Academic Press, Inc. pp. 17–18. ISBN 0-12-044250-7.