Performance and Mechanism of Hydrolyzed Keratin for Hair Photoaging Prevention.
Level 5 - mechanism / opinion, no new human data
Bench-top in vitro experimental study on hair fibers without human clinical subjects.
PubMed 40076404 · doi:10.3390/molecules30051182
What was done
Researchers evaluated the protective effects and mechanism of wool-derived hydrolyzed keratin on hair exposed to ultraviolet (UV) radiation. They used scanning electron microscopy (SEM) and fluorescent penetration assays to observe cuticle deposition and cortical penetration. Tensile strength of treated versus untreated hair was tested following UV irradiation, and UV-induced degradation of the hydrolyzed keratin solution was assessed via free amino acid content and electrical conductivity measurements.
What was found
Hydrolyzed keratin formed a film on hair cuticles and partly penetrated into the cortex. Following UV exposure, untreated hair experienced a 14.32% reduction in tensile strength, whereas hair treated with hydrolyzed keratin maintained its tensile strength. Analysis of the hydrolyzed keratin solution under UV radiation showed an increase in free amino acid content and conductivity, indicating photodegradation into smaller peptides that facilitated deeper cortical penetration and preserved fiber integrity.
Why it matters
This study identifies a UV-activated mechanism where photolytic degradation of topical hydrolyzed keratin enables deeper hair cortex penetration, offering a functional strategy to mitigate UV-induced mechanical degradation of hair.
Limits
This was strictly an in vitro bench study on hair fibers; real-world efficacy, wash-fastness, consumer use conditions, and performance on live human scalps were not evaluated. The abstract omits sample sizes, exact UV exposure parameters (wavelength, intensity, duration), formulation details, and variance metrics for the mechanical testing.
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