I was curious about this, seeing as how most stereoisomers of active drugs are inert.
Are there common chemicals in, perhaps, house-plants or abundant in nature in general, that if were made as their stereoisomer, would have a psychoactive CNS affective profile that would be highly subjectively noticeable?
How likely is it that there are *many* we have no clue about because they haven't been synthesized for demonstratable testing?
Sometimes, a compound's enantiomer has no effect, sometimes it has different effects. Often, regardless of the effect of one enantiomer, both will be selectively prepared and patented, along with the racemate.
This Wikipedia page is remarkably informative:
http://en.wikipedia.org/wiki/Enantiopure_drug
(See especially the list of drugs whose enantiomers have remarkably different effects)
Actually we synthesise most drugs enantioselectively, nowadays, owing to the superior activity (or more beneficial activity) of one enantiomer vs another (or owing to the toxicity of one enantiomer over another).
The FDA mandated a while ago that for racemic drugs, the activity of the constituent isomers be measured. Few drugs are developed for which the therapeutic value of one enantiomer isn't known.
The same goes for atropoisomers, despite there being no mandate from any regulatory agencies to test the therepeutic activity of one over another.
In nature I can think of the atropoisomers michellamine A and B...each conformer has such a high thermal barrier of atropisomeric interconversion that they can be functionally said to exist as atropoisomers with differing optical activity.
Here's another example:
http://www.ncbi.nlm.nih.gov/pubmed/16007983
Substituted biphenyl I (BMS-207940), a selective antagonist of the endothelin A (ETA) receptor, has been proposed for the treatment of congestive heart failure. The structure of I possesses a stereogenic axis due to the hindered rotation about the biphenyl bond in the presence of its large ortho-substituents. As a result, I exhibits atropisomerism in which two nonplanar, axially enantiomers exist, which will be generically referred to as isomers A and B. Within the pharmaceutical industry, both from a scientific and regulatory point of view, characterization of enantiomeric drugs has become an important step in the development process.
As the paper suggests, they tested the effect of various conditions on the rate of enantiomeric interconversion. Likely they will attempt to alter the compound such that a barrier to interconversion exists, and the atropoisomers can be separately evaluated for therapeutic activity if this wasn't already done.
When searching for novel drugs, say via high-throughput screening which we use to check for novel molecules with high potential for biological activity, asymmetry is always considered: if a novel compound emerges which is potentially optically active, then the effect of both optical isomers will be examined.
It's a rather interesting field, especially I think, atropoisomerism.
