Peptides are an active ingredient found in many skincare products, particularly anti-ageing creams. They have been shown to revitalise skin and make it stronger and more resilient. They can also be used in supplements, such as collagen peptides which have been linked to improved strength and muscle growth. However, it is important to note that there is limited research to prove these claims and that supplements should always be taken with caution. In addition, it is important to talk to your doctor before taking any supplements as they are not regulated by the same authorities as medications.
The DPRA (OECD 442C) is an in chemico test that models the first key event of the skin sensitization Adverse Outcome Pathway – chemical reactivity with proteins. It is based on the reactivity of compounds that are suspected to cause contact dermatitis with proteins present in epidermal cells. The reactivity is determined by measuring the depletion of an artificial peptide, containing the nucleophilic amino acid residues lysine and cysteine, from the surface of epidermal cells after covalent binding to the test substance. This is achieved by high-performance liquid chromatography with UV detection. The DPRA assay is available for the testing of discreet chemicals, chemicals formulations and cosmetic ingredients under Good Laboratory Practices (GLP).
It is well established that the development of a skin rash is directly linked to the ability of a chemical to interact with epidermal proteins in the affected area. It is therefore not surprising that this type of interaction is referred to as the molecular initiating event of the allergic skin sensitization pathway. Several in vitro methods model this step, but few address the evaluation of the sensitizer potency and the determination of the molecular mechanism involved.
The kDPRA, a modification of the OECD 442C test method developed by IIVS, addresses these limitations and has been demonstrated to be highly reproducible. The kDPRA is a sensitive and accurate method for the rapid screening of chemicals, chemical formulations and cosmetic ingredients for their ability to react with epidermal proteins. The kDPRA is performed under GLP conditions using high-performance liquid chromatography with UV measurement and is a reliable and robust method for the identification of compounds with potential to form reactive haptens.
The kDPRA can be used in conjunction with other tests to provide an early and comprehensive picture of the allergenic potential of a material. It can be combined with a number of other testing techniques such as protein fingerprinting and the in-gel mass spectrometric identification of peptides. It is also a useful tool for the analysis of biological samples. direct peptides