The American Oil Chemists Society’s Annual Meeting & Expo always serves a seemingly disparate group of industries, including health and nutrition, soaps and detergents, biotechnology and agriculture, which come together every year to discuss, debate and evaluate their common denominators of fats, oils and surfactants. Last year, the AOCS welcomed the Society of Cosmetic Chemists to its table, and the SCC was back in 2016 when the AOCS held its annual event in Salt Lake City, UT last month.

It makes perfect sense, too, as cosmetic chemists have been discussing and dissecting the stratum corneum and its “brick-and-mortar” structure that is made up of cells and fats, in this case, lipids. What’s more, in recent years, cosmetic researchers have rediscovered the important role that the topical application of oils can play in maintaining skin health (see p. 66, May 2016). With that in mind, the SCC developed a two-day program with sessions devoted to lipids in cosmetics and skin care products, biorenewable polymers, surfactants in cosmetics and the skin microbiome.

“We’re now in year two and we hope to keep it going,” advised Randy Wickett, of the University of Cincinnati, who opened the first session devoted to lipids and cosmetics. Wickett provided an overview of skin structure; i.e., stratum corneum, stratum granulosum, epidermis and dermis.

“The stratum corneum is the primary barrier to water loss and penetration,” he explained. “When you tape strip the skin (20x), there is a 600% increase in water loss.”

Water loss is a key culprit in debilitating diseases such as atopic dermatitis and eczema. The SC is made up of lipids, ceramides, cholesterol esters and free fatty acids, and according to the speaker, atopic dermatitis has been linked to ceramides; specifically, the SC is lacking in longer chain ceramides and has an overabundance of shorter-chain ceramides.

Wickett reviewed some atopic dermatitis treatments including TriCeram and EpiCeram, the latter of which was developed by Peter Elias. But Wickett pointed out, as many others before him have noted, petrolatum remains one of the best barrier repair products available.

“If you can stand to use it,” he added.

Wickett closed his presentation with a look at sebaceous glands, which he referred to as holocrine glands. He noted that sebum production is highly dependent on the individual and his or her age.

“If you don’t have sebum, you don’t have acne,” he reminded the audience.

Wickett also noted that sebum is a major route for delivering antioxidants like vitamin E to the skin, adding that there is more alpha-tocopherol on the cheek.

“Hydrolysis of sebum triglyceride leads to glycerin formation,” he concluded. “ So, is sebum contributing to hydrolysis of skin? We still don’t know the answer.”

A Clean Start
Lipids play an important role in healthy skin, but too much oil is not aesthetically acceptable. KP Ananthapadmanabhan of Unilever looked at stratum corneum lipids and their critical role in preserving barrier integrity during cleansing. After reviewing the make-up of a typical moisturizing cleanser, the speaker noted, “surfactants don’t know when to stop and that leads to dry skin. The stratum corneum has 15% water, which can be lost during the cleansing process.”

Consumers want what surfactants have to offer; i.e., good foam; but common surfactants such alkyl carboxylates, alkyl isethionates, alkyl ether sulfates and alkyl betaines, interact with the proteins and lipids found in the SC—which is evident in the common “tightening” sensation that consumers feel after washing. 

“From a cleansing point of view, we want to remove sebaceous lipids, but not the intercellular lipids,” Ananthapadmanabhan explained.

To help remedy the problem, formulators are incorporating fatty acids into their products.

“A cleanser pre-saturated with lipids replenishes fatty acids that are otherwise lost through cleansing,” he explained, before detailing a new directly esterified fatty isethionate with ultra-mild glycinate. A formula that he described “as mild as water.”

“We need a holistic approach to product engineering to provide superior care while not compromising on sensories,” concluded Ananthapadmanabhan.

Procter & Gamble’s Karl Wei described a body wash structured surfactant system that is comprised of highly concentrated multilamellar vesicles. The system improves skin by depositing lipids on skin during cleansing.

To assess the efficacy of the formulation, P&G took a high-throughput clinical biomarker approach, which provides an objective, non-invasive measurement of the SC barrier. According to Wei, the high-lipid depositing body wash:

• Increased 2-pyrrolidone-5-carboxylic acid (PCA) in 2-3 weeks;
• Decreased interleukin production;
• Increased keratin 1, 10 and 11 and
• Reduced the total proteins removed.

Hair Today…
Lipids, as already noted, play an important role in the delivery of actives to the skin. Imran Ahmed of Jinn Pharmaceuticals said his company has already created lipid-based Amphotericin B Gel for fungal infections. Now, Jinn researchers have utilized lipids to create MorrF, a combination of Minoxidil and Finasteride to treat baldness or more specifically, to inhibit DHT formation. The lipids act as a reservoir to prolong the delivery of the active ingredients. According to Ahmed, MorrF is superior to Mindoxidil, without the loss of libido or erectile dysfunction that is associated with Finastride.

“Our lipid-based products show marked improvement of hair growth,” he concluded.

Biorenewable Polymers
In a session devoted to biorenewable polymers, Brian Chisolm of North Dakota State University provided an overview of novel, plant oil-based polymers. According to researchers, “living” polymerization provides for precise molecular weight/viscosity control. Novel biobased vinyl ether monomers were successfully produced from plant oil triglycerides as well as eugenol. By using an appropriate cationic polymerization system, novel polymers could be produced that retained unsaturation derived from the biobased starting material.

According to Chisolm, the retention of pendant unsaturation, coupled with the ability to utilize copolymerization, provided significant value for thermoset applications. He concluded that copolymerization provides the opportunity to tailor properties over a wide range to meet application requirements.

Careful integration of non-renewable chemistry can help maximize overall sustainability, noted Mike Fevola of Johnson & Johnson. He described the benefits of Natrasurf-PS-111, a superhydrophilic/amphopilic copolymer that is very mild to skin and eyes with good foam, too. The material is 90% renewable. Fevola explained that while it was possible to create a 100% renewable material, it wasn’t worth the tradeoffs. Furthermore, Natrasurf-PS-111 is low-energy and solvent-free with 100% atom economy (no waste). Fevola said it is also non-toxic, readily biodegradable and the spray-dried powder is self-preserving.

“It outperforms most foaming surfactants on environmental metrics and has improved skin compatibility,” he said, noting that the material has already been deployed in Aveeno Skin-Relief Gentle Scent.

According to Fevola, combining green chemistry design principles with biobased polymer platforms enables the development of new functional cosmetic ingredients. However, he reminded attendees that effectively creating new ingredients from biobased polymer platforms requires technical insights obtained from functional analysis and mechanistic understanding.

Fevola concluded by stressing that emphasis must be on improved performance and/or new benefits; biobased alone is not a benefit.

The wide-ranging session also included presentations on agricultural waste and non-traditional oil in polyol synthesis, sucrose octaesters as reactive diluents for alkyd coatings.

More on Skin & Surfactants
Paolo Giacomoni, Elan Rose International, led off a session on surfactants and their impact on skin care formulation. He noted that nearly all formulas are based on oil and water, and surfactants, of course. These emulsifying agents, whether anionic, nonionic, amphoteric or a combination, reduce skin’s level of fatty acids and cholesterol. No wonder then, that there is a correlation between surfactant use and xerosis.

“The use of soap can have an incredible effect on skin,” Giacomoni observed.

These effects include production of interleukin-1B and 8 and the production of heat-shock proteins. However, proper selection of surfactants and their mixtures enables formulators to create less irritating products.

For more on the AOCS/SCC meeting, visit nitesh_happi.rodpub.com.