1. Usage of Synthetic Peptides in Cosmetics for Sensitive Skin
Diana I S P Resende, Marta Salvador Ferreira, José Manuel Sousa-Lobo, Emília Sousa, Isabel Filipa Almeida Pharmaceuticals (Basel). 2021 Jul 21;14(8):702. doi: 10.3390/ph14080702.
Sensitive skin is characterized by symptoms of discomfort when exposed to environmental factors. Peptides are used in cosmetics for sensitive skin and stand out as active ingredients for their ability to interact with skin cells by multiple mechanisms, high potency at low dosage and the ability to penetrate the stratum corneum. This study aimed to analyze the composition of 88 facial cosmetics for sensitive skin from multinational brands regarding usage of peptides, reviewing their synthetic pathways and the scientific evidence that supports their efficacy. Peptides were found in 17% of the products analyzed, namely: acetyl dipeptide-1 cetyl ester, palmitoyl tripeptide-8, acetyl tetrapeptide-15, palmitoyl tripeptide-5, acetyl hexapeptide-49, palmitoyl tetrapeptide-7 and palmitoyl oligopeptide. Three out of seven peptides have a neurotransmitter-inhibiting mechanism of action, while another three are signal peptides. Only five peptides present evidence supporting their use in sensitive skin, with only one clinical study including volunteers having this condition. Noteworthy, the available data is mostly found in patents and supplier brochures, and not in randomized placebo-controlled studies. Peptides are useful active ingredients in cosmetics for sensitive skin. Knowing their efficacy and synthetic pathways provides meaningful insight for the development of new and more effective ingredients.
2. Physico-chemical characterization of formulations containing endomorphin-2 derivatives
Anna Olejnik, Alicja Kapuscinska, Grzegorz Schroeder, Izabela Nowak Amino Acids. 2017 Oct;49(10):1719-1731. doi: 10.1007/s00726-017-2470-x. Epub 2017 Jul 27.
In this study semisolid formulations containing AcYPFF (N-acetyl-Tyr-Pro-Phe-Phe-NH2) tetrapeptide were obtained and characterized in terms of rheology, stability by multiple light scattering and particle size distribution by laser diffraction. Additionally, the release studies of tetrapeptide from formulations obtained were performed. The influence of different factors such as semisolid and membrane type on tetrapeptide release rate was examined. The release experiments of tetrapeptide modified with palmitoyl group (PalmYPFF) were also carried out. The results proved that formulation type and its rheological properties strongly determined the permeation process of the tetrapeptide. The fastest release of tetrapeptide was observed from hydrogel that had the lowest viscosity. The kinetic data of tetrapeptide released from oil-in-water (o/w) and water-in-oil (w/o) emulsions prepared at elevated temperature showed good fit to the Higuchi equation, whereas when AcYPFF was released from oil-in-water (o/w) emulsion prepared with the addition of auto-emulsifier high linearity with Korsmeyer-Peppas model was observed. While when tetrapeptide was released from Hydrogel the most suitable model was the first-order kinetics. It was suggested that mechanism that led to the release of tetrapeptide from all formulations was non-Fickian diffusion transport. The presence of palmitoyl group changed the solubility of tetrapeptide both in formulation and receptor fluid and thus the release rate of active compound was modified.
3. Low Energy Conformations for Endogenous Mu-Receptor-Specific Peptides
Bo Lin, Robert P Carty, Matthew R Pincus Protein J. 2020 Jun;39(3):217-223. doi: 10.1007/s10930-020-09903-2.
We have computed the low energy minima for the two endomorphin peptides, N-acetyl-Tyr-Pro-Trp-Phe-NHCH3 (endomorphin 1) and Tyr-Pro-Phe-Phe-NHCH3 (endomorphin 2) in aqueous solution. These peptides block pain without inducing the harmful side effects of the opiates that bind to the same mu opiate receptor but have short half lives. From over 1000 starting conformations for each peptide, we find less than 200 low energy structures whose conformational energies were ≤ 5 kcal/mole of the energy of the global minimum. The most probable conformations calculated using the Boltzmann distribution for both peptides were similar to one another. Using the letter representation for backbone conformational states, these most probable structures were D A E E for endomorphin 1 and E A E E for endomorphin 2. Both of these structures form reverse turns at Pro 2-Trp (Phe) 3 resulting in the juxtaposition of the aromatic rings of Tyr 1 and Phe 4. The Trp residue of endomorphin 1 points to the back of the reverse turn. These features may be useful in the design of non-peptide analogues that will have longer half-lives than the peptides.