CHIRAL INGREDIENTS IN COSMETICS
Dr. Charlene DeHaven M.D.
Clinical Director, INNOVATIVE SKINCARE
proteins) are, in general, of L-chirality or rotated to the
left. Here, “L” or “levo” refers to left. Sugars, on the
®
other hand, which are used to build the genetic code of
EXPLANATION OF CHIRALITY
DNA, are of D-chirality or rotated to the right. “D”
The term “chirality” when referring to a “chiral
refers to “dextro” or right. Most chemicals (for example,
ingredient” refers to the rotation of a compound
enzymes) synthesized within the body are of L-rotation.
composed of a string of molecules about an axis. These
This L-rotation has been speculated to occur as a
long and winding strings of molecules may be rotated,
relationship to the earth’s rotation when early life began
in some instances, to the right and, in others, to the left.
and also to relate to the rotation of groups of serine, an
The sum of carbon, oxygen, hydrogen and other
amino acid. However, biological systems, including
molecules within two chiral compounds is the same,
humans, recognize and use compounds with varying
although these identical number of molecules are
chirality. This probably relates to the efficiency of life’s
arranged slightly differently in space; these compounds
survival mechanisms and the ability of organisms to
are called “enantiomers” of each other, meaning they
utilize a variety of substances in their environments.
have the same number of each type of molecules but are
configured in a slightly different way in space. Most
Within organisms, occasionally a receptor site (for
simply stated, chiral compounds are not symmetrical.
example, a receptor site for a specific molecule in the
They cannot be superimposed directly upon their own
intestine) will recognize either the D form or the L form
mirror image. A simple illustration of chirality is right
more efficiently. Occasionally, a drug is slightly more
and left-handedness. The right and left hands of any
efficient if it possesses only one of these chiralities.
given individual are not exactly alike, each containing
These,
unique patterns, lines, and tissue prominences, and, if
sometimes
laid on top of one another, do not fit within the same
difference in the real world of biochemical functioning.
image. Yet, even though different and, certainly, not
When medicines of different chiralities were closely
exact matches, they are both useful to individual
evaluated, there was no practical difference in efficacy
functioning. Likewise, many other body parts are not
between the L-form and the mixed form.
however,
so
are
very
academic
minor
they
differences
make
no
and
practical
symmetrical.
CHIRAL COMPOUNDS IN COSMETICS
Since organisms on earth tend to synthesize more of the
L-rotated compounds, a skin product obtained from
plant source will contain the vast majority of its
compounds in L-form. However, there is always some
shift back and forth in nature between the L-form and
D-form. It is nearly impossible to keep only one rotation
in solution at any given time. A mixture containing both
the D-form and L-form of a substance is termed
“racemic” This means that, even if a substance is
advertised as being “chirally pure”, it cannot remain so
since nature causes a continuous shift back and forth
Considering rotational axis of biochemical compounds
between its own enantiomers.
within the body, amino acids (the building blocks of
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It is not necessary or even possible to have a “chirally
Chamberlain, JC Drach, LB Townsend; J Med Chem.
1998 Apr 9;41(8):1242-51.
pure” skin product. Nature makes it impossible for such
a product to exist for even a nanosecond. A “racemic”
or chirally mixed substance is not harmful. Biochemical
systems such as humans and our receptors are able to
use and recognize a variety of enantiomers because of
“Osomoprotection by Pipecolic Acid in Sinorhizobium Meliloti:
Specific Effects of D and L Isomers”, K Gouffi, T
Bernard, C Blanco; Appl Environ Microbiol. 2000
Jun;66(6):2358-64.
survival efficiency.
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All materials contained on this document are protected by United States copyright law. You may not modify, remove, delete, publish, transmit, reproduce or in any way exploit the content of this document, in whole or in part.
© 2015 Science of Skincare, LLC. All rights reserved.
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