The impact of AP collagen peptides (APCPs) on hair shaft elasticity and gloss: A comprehensive analysis

The study shows APCPs enhance hair elasticity and gloss by increasing amino acids, lipids, chemical bonds intensities, and keratin expression while reducing cuticle roughness in hair. • APCPs increase the levels of essential amino acids associated with hair elasticity. • APCPs augment lipid components, such as 18-methyleicosanoic acid (18-MEA), lauric acid, oleic acid, 11,13-eicosenoic acid, behenic acid, and squalene. • APCPs amplify the intensity of bonds such as S=O, C=O, cystine, C–N, and C–H. • APCPs elevate the expression of Keratin 17, Keratin 31, Keratin 85, and Keratin 86. • APCPs enhance the content of bonded water and moisture in the cortex of hair. • APCPs reduce cuticle surface roughness. AP collagen peptides (APCPs) are enzymatically decomposed collagen peptides that have been shown to promote hair growth and improve hair cuticle structure and thickness in mice. However, their impact on the elasticity and gloss of human hair has not been thoroughly investigated. Therefore, this study sought to identify the factors affecting hair elasticity and gloss in APCPs-treated human hair follicles (hHFs). Using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) analysis, changes in amino acid content related to hair elasticity and lipid components associated with hair gloss were measured. As a result, APCP treatment led to increases in proline and cysteine amino acid, as well as in lipid components such as 18-methyleicosanoic acid (18-MEA), lauric acid, oleic acid, 11,13-eicosenoic acid, behenic acid, methyleicosanoic acid and squalene. Fourier-transform infrared spectroscopy (FT-IR) analysis of hair cross-sections indicated an increase in the intensity of bonds such as S=O, C=O, cystine, C–N and C–H in APCPs-treated hHFs. Additionally, APCPs elevated the expression of Keratin 17, integral to the inner root sheaths (IRS) and outer root sheaths (ORS), as well as Keratins 31, 85, and 86, components of the hair cortex and medulla. APCPs treatment also resulted in increased bonded water and moisture content in hHFs, along with a reduction in cuticle surface roughness. These findings suggest that APCPs may have the potential to enhance hair elasticity and gloss.