anti wrinkle octapeptide SNAP-8 is an elongation of the famous hexapeptide
ARGIRELINE®. The study of the basic mechanism of anti-wrinkle activity
led to the revolutionary heaxapeptide which has taken the cosmetic world
by storm. Those same studies have been applied to bring another addition
to the Botulinum Toxin inspired family of peptides.
Cause of Facial
of the most striking signs of skin aging is increased wrinkling of the
face. This can occur naturally over time and is identified by certain
biochemical, historical and physical changes that are enhanced by environmental
exposure. These are other secondary factors that can b cause characteristic
folds, furrows and creases of the face. These include the constant pull
of gravity, frequent and constant positional pressure of the skin of the
face (e.g. during sleep) or repeated facial movements caused by the contraction
of the muscles of facial expression. In molecular mechanism involved in
face aging is directly related to changes in the conformation of the collagen
triple helix, degradation of the elastin polypeptides and certain disorder
in the packing of lipidic matrix of the skin.
has been clearly established that these conformational changes and the
disturbance of the perfect packing of the lipid matrix can be significantly
avoided by modulating muscle contraction.
Muscles are contacted when they receive neurotransmitter
released from inside a vesicle. The SNARE (SNAp REcetor) complex is essential
for this neurotransmitter release at the synapsis. It is temary complex
formed by the proteins VAMP, Syntaxin and SNAP-25 (SyNatosomal Associated
Protein). This complex is like cellular hook which captures vesicles and
fuses them with the membrane for the release of neurotransmitter.
SNAP-8 is a mimic of the N-terminal end of SNAP-25 which
completes with SNAP-25 for a position in the SNARE Complex, thereby modulating
its formation. If the SNARE complex is slightly destabilized, the vesicle
can not release neurotransmitters efficiently and therefore muscle contraction
is attenuated , preventing the formation of lines and wrinkles.
SNAP-8 reduces the depth of wrinkles on the face caused by the contraction
of muscles of facial expression, especially in the forehead and around
eyes. SNAP-8 is a safer, cheaper, and milder alternative to Botulinum
Toxin, topically targeting the same wrinkle formation mechanism in a very
In VIVO Testing
Inhibition of SNARE complex formation
assay the efficacy of small peptides on the stability of the SNAR complex
we developed an in vitro method that enabled us to follow the formation
and thermal stability of the reconstituted SNARE protein complex. The
rational of the method evaluates the antagonistic competitive efficacy
of small peptides patterned after the SNAP-25 N terminal domain with the
wild type protein on its capacity to assemble with syntaxin and synaptobrein
forming by the SNARE complex.
The results prove
that short peptides from the N-terminal end of SNP-25 compete with the
native protein and inhibit the formation of the SNARE complex by effecting
Modulation of catecholamine release in chromaffin cells
EGTA is metal chelator used as a negative control, because it captures
Ca2+ which is essential for vesicle fusion and catecholamine release.
One of the problem of working with peptides with similar effects but different
potency is to compare their activities.
release tests at different concentrations of peptides were performed,
in order to plot the dose response curves needed to calculate the IC50
values for the different peptides. We can therefore quantity and compare
the exocytosis blocking activity, which is directly related to the anti
The IV50 is the 50%
inhibitory concentration, in this case, the concentration of active that
inhibits 50% of catecholamine secretion. The lower IC50, the smaller the
amount needed to inhibit secretion 50%, and the more active the compound
ESUP-E is the most
potent synthetic peptide in terms of catecholamine inhibition. It is a
long peptide, not suitable for cosmetic application, but is used as reference
to define AAUs.
In VIVO Testing
Anti wrinkle test
on healthy volunteers
topography analysis for measuring the effectiveness of an cream containing
10%of SNAP-8 solution were performed obtaining silicon imprints from around
the eyes from 17 healthy women volunteers. Silicon imprints were obtained
pre-test and after 28 days of twice a day applications. Analysis of imprints
were performed by control laser scanning microscopy to assess the evolution
of the skin surface before and after the treatment. Skin topography images
from the three dimensional reconstruction of optical sections are shown.
It can be observed that the depth of the wrinkle has significantly decreased
after 28 days of treatment which confirms the validation of the biochemical
Skin topography images before (left) and after (right) a 28 days treatment
with a cream containing 10% SNAP-8 solution.
are compared to a previous test (Oct, 2001) performed by the same company
using the same technique, testing a cream with 10% ARGIRELINE® solution
on 10 women volunteers.
The maximum reduction
value found for 10% SNAP-8 solution was -63.18%.
An observed in vitro,
the two extra amino acid from SNAP-25 sequence seems to moderately increases
the anti-wrinkle activity.
The construction is
that, both in vivo and in vitro testing suggests that SNAP-8 is approximately
30% more active than its parent peptide ARGIRELINE®.
more about SNAP-8