Cysteine Peptide For Direct Peptide Reactivity Assay (DPRA) – Other Categories

Cysteine peptide (Ac‑RFAACAA‑COOH) is used in combination with Lysine peptide (Ac‑RFAAKAA‑COOH) in the Direct Peptide Reactivity Assay (DPRA) test. Direct Peptide Reactivity Assay is used in cosmetic applications for the characterization of the skin sensitizing potential of a substance,framed by OECD Guideline no 442. The molecular initiating event (MIE) in skin sensitization is a binding between epidermal proteins and the sensitizing chemical substance. MIE is part of the adverse outcome pathway (AOP) of skin sensitization. It is thanks to the properties of Cysteine peptide and Lysine peptide that the chemical binding will be able to take place,so these synthetic heptapeptides will mimic the reaction of a skin exposed to a substance. Binding between nucleophilic proteins and electrophile substance will be measured by High Performance Liquid Chromatography (HPLC). Therefore,the decrease in Cysteine peptide and Lysine peptide levels will be a sign of sensitizing event. Depending on the rate of depletion,the sensitizing character of a molecule will be determined (see table at the bottom of the page). In chemico DPRA test also has wider applications such as hazard classification in cosmetics,but also for pharmaceuticals and biocides. It is a good alternative to animal experimentation. The DPRA test is a major advance in characterization of sensitizing elements. It is a non-animal approach. Skin sensitization studies are the cause of death of hundreds of thousands of mice worldwide each year. The DPRA test is therefore a preferred alternative to animal studies such as mouse local lymph node assay (LLNA). On the other hand it is a more effective method,as 22% of skin sensitizers are not detected with the LLNA test,and half of the sensitizers are classified in the wrong category. As a basis for 'integrated approaches to testing and assessment' (IATA),the OECD has therefore developed the DPRA test via the adverse outcome pathways (AOP). OECD has thus enabled the DPRA test to become a new element of choice in the animal study of sensitisers,as a harmonised and validated test.

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