Peptides: Tiny Molecules with Big Results

As consumers increasingly demand better, faster and more noticeable results from their personal care products, raw material suppliers continue to deliver more miraculous materials. The latest materials yielding the best results are peptides. This article will explore the science of these remarkable structures which are enabling companies to offer their customers products that can provide big results.

A Scientific Story That Can’t Be Told

First things first, let’s put these materials, and the products containing them, into perspective. The facts are that as cosmetics, the science of HOW these materials work can’t be explained to consumers in any form of marketing. Cosmetics are defined as products used externally to alter the appearance of the skin; and all cosmetic marketing and ingredients must comply with regulatory requirements. This means that companies cannot provide the physiology of how these ingredients work to promote their products. A promotional activity is defined as anything that a company does or says that may directly or indirectly lead to the sale of a product. What this means is that while I can explain the science of how these materials work to you in this article, a company providing a product containing these materials to the marketplace cannot explain the science to a consumer – as this would be seen as a form of promoting their product and contain physiological claims which can’t be made for a cosmetic. Even if the science was explained on a different page of their web site, the site as a whole would be considered as contributing to the sale or promotion of a product so must comply with the regulations and not go beyond claims of the visible difference that may be seen through using the product. A company could set up a totally unrelated site, no branding, no names – but then any education on that page would not contribute to their sales as the consumer would have no way of knowing which products it relates to, or where they could purchase them. Since promoting personal care and cosmetics is such a competitive (and expensive) exercise in marketing, no company is going to invest the funds to tell a nameless story that can’t ultimately, in some way, lead to a sale of their products.

So what you read here is the science behind these materials; but don’t wonder why your products don’t tell the same story – the fact is, they can’t!

Peptides – Tiny Molecules, Big Results

Peptides are, chemically speaking, short chains of amino acids linked together by peptide bonds. In the personal care industry, the term ‘peptide’ refers to molecules that are short chain amino acids – very small substances – that are able to traverse to the stratum basale and signal physiological changes at the dermal level; or in some cases, effectively travel into the dermis and compete with neurotransmitter binding sites to temporarily alter a physiological activity.

While there are now peptides available to combat the signs of ageing, whiten the skin and even lengthen the lashes, in this article I’ll be focussing on one of the most popular peptide mechanisms we’ve seen in this industry to provide an example of how one of these amazing materials works within the skin – but don’t forget there are many other peptides out there with similar amazing molecular bioactivity to achieve fast and dramatic results.

The specific example I am focussing on here relates to the botox-like action of a hexapeptide. This material addresses the signs of ageing by inhibiting muscular contractions that disturb the packing of the lipid matrix. If you can stop the contractions, the lipid matrix maintains its profile and deformation of the skin does not occur – you effectively stop the appearance of a wrinkle. This is done by providing a ‘mimic’ peptide in cosmeceutical form which binds in place of the peptide normally produced by the body, to prohibit the muscular contraction. 


A ‘SNARE’ complex is normally required to release a neurotransmitter which tells a muscle to contract. This SNARE complex contains a protein known as SNAP-25; but if this is replaced by an analogue peptide (the topically applied ‘mimic’), the SNARE complex is destabilised, the neurotransmitters are inhibited, and the muscle contraction prohibited. The result – less facial expressions and less wrinkles!

Delivery Is Crucial

One of the biggest challenges a Cosmetic Chemist always faces is delivery of an active to the required site. This is because the skin and its layers are, by default, a very good protective barrier. As an example, and to help you understand the way some substances can selectively travel through the outer layers of the skin, take note of the following pathways and sizes:

Particular Size nm (10-9)m Size microns (10-6)m
Stratum corneum hydrophilic pathways
(substances would need to be smaller than this if hydrophilic to traverse the stratum corneum)
0.4 0.0004
Cell membrane 6-10 0.006 – 0.01
Stratum corneum lipid bilayer
(substances would need to be smaller than this if lipophilic to traverse the stratum corneum)
13 0.013
Stratum corneum intercorneocyte space 20-75 0.02 – 0.075
Stratum corneum thickness 10,000 – 40,000 10 — 40

To pass through the stratum corneum (and deeper layers) substances either need to pass through the cells or around them (the intercorneocyte space). As you can see, water soluble substances need to be extremely small to traverse the stratum corneum. Lipid soluble substances can travel through lipid bilayers when small, but still have similar distances to travel. Even if they can enter a pathway, they then have an incredibly large distance to travel (compared to their size) to penetrate beyond the stratum corneum! This is particularly important with the delivery of peptides – they are extremely small and can traverse to the stratum basale and beyond; but compared to their size, they need to travel an incredibly HUGE distance – so the vehicle, the product base they are in, becomes an essential component to enable the bulk of their passage through the epidermis. Once they are ‘delivered’ to the stratum basale, their ability to travel into the dermis and make a difference is certain – but getting them there is the hard part!

Due to the complexity of the skin and the difference in the skin’s layers, substances that have a molecular weight below 1000 daltons may be able to penetrate the epidermis if in an amphiphilic base. Standard emulsions are amphiphilic bases, containing both hydrophilic (water) and hydrophobic (lipid) phases as well as amphiphilic substances (the emulsifiers), so act as excellent delivery vehicles for small substances to at least the deeper layers of the stratum corneum. The use of osmolytic substances such as humectants can enable penetration to the stratum granulosum level. To provide the required activity, peptides must be provided to the skin in a suitable carrier base to reach the stratum basale target site — this is usually best achieved using an emulsion (amphiphilic) base combined with humectant agents and/or liposomal delivery agents.

Is There Potential For Overpromising And Underperforming?

There is absolutely no doubt these materials are expensive. Comparatively speaking, they are more costly than most other actives currently available. However, when used in the appropriate inputs and formulated into a compatible base product with good delivery mechanisms to ensure these substances get to where they are most active, the results are certain. What this means is a formula created properly, using the right amount of these materials, will ALWAYS get results.

There could be the potential for companies to try to cut costs of product to meet a required sales price; and if that is the case then peptides would undoubtedly be the first to be reduced – but that is really to the detriment of that company’s development and not a result of the peptide under-performing. Another potential issue is providing these powerful substances in a low delivery base – using key materials to ensure delivery of these actives to the stratum basale will give a competitor product a leading edge over another brand using the same active in the same proportion but in a poor delivery base. This comes down to clever formulating to ensure the best possible visible results for a consumer.

Finally, don’t think that appearing low on an ingredient list means there isn’t much of this substance present – on the contrary, and particularly with peptides – it is because these substances are so small that not much is needed to get the great results. As little as 77mcg is all that is clinically required, per application, to get the amazing results with the peptide I discussed in this article – some other peptides are required in even smaller quantities for other skin or hair benefits!

How Do I Know If A Raw Material Contains a Peptide?

You can ask your Distributor or Sales Representative for materials containing peptides – they can discuss the different peptides present in their products and mode of action but remember, this marketing can’t be used to promote the sale of a product, even verbally, to a consumer. Luckily, while you can’t say how these products work, you won’t really need to —  the visible results of using these remarkable materials speaks for themselves!

Belinda Carli is the Director of the Institute of Personal Care Science (IPCS). IPCS provides distance and on-site training in Cosmetic Formulation, Brand Management and Regulatory Affairs as well as providing formulation, product development and regulatory consulting services. Contact Belinda and the team for assistance with your training, formulation, brand management or regulatory requirements: or visit for more information.

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