| • A functional replacement
for AHA's • Superior efficacy
at lower use levels
• Can be formulated at neutral
pH
• Virtually non-irritating
for milder formulations
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Immobilization of enzymes on high molecular weight
polymers improves stability and overall performance of the
enzyme, while providing a safe and effective system for the
topical delivery of enzymes to the stratum corneum.
Papain represents
the first application of this novel technology for the immobilization
of a plant-derived enzyme onto natural or synthetic polymers.
Papain is a proteolytic enzyme that specifically hydrolyses
proteins such as collagen (a protein found in skin). Papain
was developed as an alternative to AHA's (Alpha Hydroxy Acids).
Exfoliation of dead and damaged skin cells from the skin's
surface enhances skin smoothness and actually encourages the
development of newer cells, resulting in smoother younger
looking skin.
Papain is a natural proteolytic enzyme (Mol wt around 23,000
daltons) extracted from Carica papaya latex. The pH at which
papain shows activity is quite broad (pH 4.0-8.0) with an
optimum between pH 6.0-7.0. Papain “softens” and
digests the protein components of the intercellular matrix.
The drawback of papain in its natural state is its molecular
size — it could potentially penetrate deeper into the
skin than is desired.
Papain has been shown to be highly effective at promoting
turnover of the stratum corneum. When applied on a daily basis
to DHA-treated skin, 1% Papain was as effective as 8% and
10% lactic acid lotions at exfoliating the stratum corneum.
The Effect of pH on Enzyme
Activity
Enzymes are most active at a certain pH. Generally, the activity
of an enzyme drops of at extreme pH. However, in some cases
the effect is reversible. Consequently, it is possible to
compound with enzymes subjected to extreme pHs and recover
the activity upon neutralization. The activity of Papain is
greatest at a pH of 6, but the enzyme retains approximately
75% of its activity between a pH of 5 and 7.
Papain is Non-Irritating to Skin
Papain is an effective exfoliant that is not irritating to
skin. While Balsam
of Peru increases the redness of skin, Papain is no more irritating
than pure water.
Papain Remains on the Stratum
Corneum
Papain is more active in the upper layers of the stratum corneum.
This is due to the “anchoring” effect attributed
to the high molecular weight of the carbomer backbone. Once
applied, the activity of the enzyme steadily increases for
two hours, and then rapidly decreases. After three hours have
elapsed, the activity of Papain is reduced to zero. In the
lower stratum corneum, the activity of the enzyme shows a
slower progression towards zero.
Stratum Corneum Turnover with Papain in a finished product
Areas of skin were first stained under standard conditions
with DHA. Creams are shown with increasing levels (%) of Papain
from left to right.
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