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Chirality (chemistry) Two enantiomers of a generic amino acid that are chiral. (S)-Alanine (left) and (R)-alanine (right) in zwitterionic form at neutral pH. In chemistry, a molecule or ion is called chiral (/ ˈkaɪrəl /) if it cannot be superposed on its mirror image by any combination of rotations, translations, and some conformational changes.
Chirality(/kaɪˈrælɪti/) is a property of asymmetryimportant in several branches of science. The word chiralityis derived from the Greekχείρ(kheir), "hand", a familiar chiral object. An object or a system is chiralif it is distinguishable from its mirror image; that is, it cannot be superposed(not to be confused with superimposed) onto it.
There are three common naming conventions for specifying one of the two enantiomers (the absolute configuration) of a given chiral molecule: the R/S system is based on the geometry of the molecule; the (+)- and (−)- system (also written using the obsolete equivalents d- and l-) is based on its optical rotation properties; and the D/L system is based on the molecule's relationship to ...
Chiral analysis refers to the quantification of component enantiomers of racemic drug substances or pharmaceutical compounds. Other synonyms commonly used include enantiomer analysis, enantiomeric analysis, and enantioselective analysis. Chiral analysis includes all analytical procedures focused on the characterization of the properties of ...
Enantiopure drug. An enantiopure drug is a pharmaceutical that is available in one specific enantiomeric form. Most biological molecules (proteins, sugars, etc.) are present in only one of many chiral forms, so different enantiomers of a chiral drug molecule bind differently (or not at all) to target receptors.
Homochirality is a uniformity of chirality, or handedness. Objects are chiral when they cannot be superposed on their mirror images. For example, the left and right hands of a human are approximately mirror images of each other but are not their own mirror images, so they are chiral. In biology, 19 of the 20 natural amino acids are homochiral ...
A chiral switch is a chiral drug that has already approved as racemate but has been re-developed as a single enantiomer. [ 1 ][ 2 ] The term chiral switching was introduced by Agranat and Caner in 1999 [ 3 ] to describe the development of single enantiomers from racemate drugs. For example, levofloxacin is a chiral switch of racemic ofloxacin.
Moving from a racemic drug to a chiral specific drug may be done for a better safety profile or an improved therapeutic index. This process is called chiral switching and the resulting enantiopure drug is called a chiral switch. [10] As examples, esomeprazole is a chiral switch of (±)-omeprazole and levocetirizine is a chiral switch of (± ...