Multiple Discriminant Analysis of Fatty Acids from Male Scalp Hair Lipids

Abstract

Lipids extracted from the scalp hair of Caucasian boys, teenagers and adults and Black Teenagers of a boarding school, were saponified and the groups compared with respect to the total fatty acids by multiple discriminant analysis. The lipid yields from Black ranged higher than those from Caucasians. Among the Caucasians, differences based on age were not significant. The total acids of hair lipids from Blacks differed significantly as compared to those of the White groups, a trend also supported by analyses of acids in lipid classes of men 24–70 years of age. Hair from the latter was pooled according to race and scalp condition (balding and non‐balding). With the latter 4 adult categories, acids of the mono‐, di‐ and tri‐acylglycerols and the free fatty acids were ascertained and compared, both on the basis of the over‐all acids as well as in terms of the prominent saturated and unsaturated homologs. Racial differences were encountered in the fatty acids, the saturated acids distinguishing the free fatty acids and triacylglycerols and the unsaturated, the mono‐ and di‐acylglycerols. For each category, the ratios of free fatty acids to triacylglycerols were not significant in contrast to the component acids as such. As based on the acids, significant differences also occurred with scalp condition in the respective racial groupings.

Universality of Hair as a Nucleant: Exploring the Effects of Surface Chemistry and Topography

“…The CaCO 3 and KNO 3 crystallization experiments revealed that the different surface modification strategies had marked effects on the nucleating properties of human and dog hairs. The outer surface of the hair is the cuticle layer, which consists of ≈75% highly cross-linked keratin and ≈25% lipids, of which 18-methyleicosanoic acid is the most abundant . Lipids are either free (unbound) or covalently attached to keratin through thioester linkages (bound).…”

“…The contribution of surface chemistry to the behavior of the hairs was investigated by employing three surface treatment strategies by immersion in: (i) ethanol, (ii) petroleum ether, and (iii) hydrogen peroxide before water rinsing (Section S1.1). Petroleum ether removes lipids from the surface, ethanol removes lipids and denatures proteins, and hydrogen peroxide oxidizes the proteins on the hair surface, altering its chemistry and surface charge. − …”

“…The outer surface of the hair is the cuticle layer, which consists of ≈75% highly crosslinked keratin and ≈25% lipids, of which 18-methyleicosanoic acid is the most abundant. 33 Lipids are either free (unbound) or covalently attached to keratin through thioester linkages (bound). The outermost surface of the cuticle is known as the epicuticle (Figure 5a), an approximately 13 nm layer that contains a large portion of covalently bound lipids.…”

Inelastic Electron Tunneling Spectroscopic Study of Biological Compounds in Human Sweat Adsorbed on Alumina

“…An important contribution of this fatty acid has been also reported in the lipids from scalp hair bulbs. [41][42] Tunneling spectroscopy is now recognized to be a very sensitive tool to detect adsorbed species on the oxide surface. The sensitivity is high enough to detect less than 1013 molecules/cm2, which corresponds to a fraction of a monolayer of the surface.44 •45 The selective detection of the fatty acids in the benzene phase of the sweat is because of this high sensitivity for carboxylic acids.…”