Key Locations of Oxidative Damage in Human Hair Keratins After Heat and Ultraviolet Light Exposure

September 2025 in “ International Journal of Cosmetic Science ”

Jeffrey E. Plowman, Anita J. Grosvenor, Santanu Deb‐Choudhury, Fraser I. Bell, Julie Roberts, Stefan Clerens

oxidative damage human hair keratins heat exposure ultraviolet light exposure Type I K31 Type II K85 cysteine modifications disulphide bonds cysteic acid dehydroalanine LC-MS/MS amorphous regions structured regions secondary structural interactions UV exposure UV light hair damage hair keratin damage

Studysummary This study observed that exposing human hair keratins to heat or UV treatments led to modifications in cysteine residues, disrupting crucial disulphide bonds and potentially reducing the structural integrity of hair similar to prolonged styling or sunlight exposure. Our plain-language summary of this paper — not a Tressless recommendation.

This study examined the effects of heat and UV exposure on human hair keratins, specifically Type I K31 and Type II K85, focusing on cysteine modifications that disrupt disulphide bonds. Human hair was subjected to treatments simulating one year of styling and environmental exposure. The research identified disulphide bond-disrupting modifications, such as cysteic acid and dehydroalanine, in both the amorphous and structured regions of the keratins. These modifications are crucial for secondary structural interactions, and their disruption can lead to a loss of structural integrity in hair, highlighting the potential damage from repeated styling and prolonged sun exposure.

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