Keratins and lipids in ethnic hair

Abstract

Human hair has an important and undeniable relevance in society due to its important role in visual appearance and social communication. Hair is mainly composed of structural proteins, mainly keratin and keratin associated proteins and lipids. Herein, we report a comprehensive study of the content and distribution of the lipids among ethnic hair, African, Asian and Caucasian hair. More interestingly, we also report the study of the interaction between those two main components of hair, specifically, the influence of the hair internal lipids in the structure of the hair keratin. This was achieved by the use of a complete set of analytical tools, such as thin layer chromatography-flame ionization detector, X-ray analysis, molecular dynamics simulation and confocal microscopy. The experimental results indicated different amounts of lipids on ethnic hair compositions and higher percentage of hair internal lipids in African hair. In this type of hair, the axial diffraction of keratin was not observed in X-ray analysis, but after hair lipids removal, the keratin returned to its typical packing arrangement. In molecular dynamic simulation, lipids were shown to intercalate dimers of keratin, changing its structure. From those results, we assume that keratin structure may be influenced by higher concentration of lipids in African hair.

Human Hair and the Impact of Cosmetic Procedures: A Review on Cleansing and Shape-Modulating Cosmetics

“…This lipid works as a lubricant decreasing friction between hair fibers and its absence influences the sensory perception of hair such as dry hair or difficulty in combing [55]. Lipid content may vary depending on several factors, such as ethnicity, gender and age [50,56,57].…”

FT-IR Microspectroscopic Imaging of Cross-Sectioned Human Hair during a Bleaching Process

“…A tightly packed hair fiber is composed of crystalline keratin, mostly in an α-helical arrangement [1] [2]. The cuticle protects the cortex from the attacks suffered by hair, and the hair's cosmetic properties, similar to the "hand" of a finished textile (i.e., stiffness, smoothness, fullness and softness, anti-drape stiffness, crispness, flexibility etc.…”

Metabolomic analysis of amino acids and lipids in human hair altered by dyeing, perming and bleaching

“…Hair lipids are mainly composed of FFAs, CH, cholesteryl sulphate, wax esters, 18-MEA, triglyceride and CERs (7). Of these hair lipids, FFAs like C22:1FA (erucic acid), C22FA (behenic acid), C24FA (lignoceric acid), C24:1FA (nervonic acid), C26FA (cerotic acid) and an integral hair lipid, 18-MEA, were depleted in proportion to the severity of hair damage.…”