Hair lipids

TLC spots with marker reveal the presence of free fatty acids (FFA), diglyceride (DG), monoglyceride (MG) but negligible amount of TG. GCMS of fatty acid— methyl esters (FAME) from lion mane presented evidence for fatty acids ranging from C9-C24 (Figs. 5.3- 5.6). Low volatility molecules like nonanedioic acid (Fig. 5.3), tridecanoic acid (Fig. 5.4), 12-methyl tridecanoic acid were also present in lion hair lipids. In addition fatty acids such as myristic, pentadecanoic, palmitic, heptanoic, stearic and octadecenoic acids (Fig. 5.5) have also been detected. Erucic... 

The data (1 to 9% extracted hair lipid) represent total matter extracted from hair clippings of individual men and women. Although the conditions for extraction can influence the amount of matter extracted from hair [138], the values here represent approximate maxima and serve to indicate the variation in the amount of extractable material from hair among individuals. Presumably, the principal material in these extracts is derived from sebum and consists primarily of free fatty acids and neutral fat (esters, waxes, hydrocarbons, and alcohols). Gloor [137] classifies the different components of sebum into six convenient groups free fatty acids (FFA), triglycerides (TG), free cholesterol (C), cholesterol and wax esters (C WE), paraffins (P), and squalene (S). 

Composition of Human Hair Lipid 93 Table 2-13. Composition of FFA in human hair lipid. 

With the exception of the Cie and C20 acids, the data in the columns of relative ratio to Cm acids of Table 2-14 are very similar for each corresponding acid. Equivalence suggests that the relative amounts of each acid in ester form would be the same as the relative ratios of the free acids and that hydrolysis may occur on standing (or other conditions) to increase the ratio of FFA to esters [134], The noteworthy exceptions are the saturated acid, which must exist in the ester form to a greater extent than is suggested by the relative ratios of free acids, and the C20 unsaturated acid, which was found only in trace quantities by Gershbein and Metcalf [141], A further conclusion from these studies is that the principal acyl groups present in human hair lipids are from the fatty acids. 

Analysis of some of the neutral material from human hair lipid (e.g., triglycerides, cholesterol or wax esters, and paraffins) provides a mixture as complex as that of the fatty acids [134,139,140,142]. Although not all the compounds of these different components of sebum have been fully analyzed, it is obvious from the discussion on fatty acids and the literature on wax alcohols in human hair lipid [142-145] that the variation in chain length and isomer distribution of all these esters must be extremely complex. 

It was indicated previously that the amount of sebaceous secretion changes with age near puberty. The composition of the sebaceous secretion also changes with age near puberty. Nicolaides and Rothman [146] have shown that the paraffinic hydrocarbon content of sebum is highest in children (boys), lower in men, and lowest in women. These same two scientists have also shown that the squalene content of the hair lipid of children, at approximately 1.35% of the total lipid content is about one-fourth that of adults (sebum from boys age 6 to 12 was examined in this study and compared to that from both men and women). In addition, the cholesterol content of the hair lipid of children is less than that from adults 3.7% versus 12.2% [146]. 

Nicolaides and Rothman [134] have shown with small sample sizes that hair from blacks contains more lipid than hair from Caucasians. Gershbein and O Neill [142] examined the distribution of fatty alcohols of human hair lipid to determine the relative amounts of fatty alcohols and sterols with regard to sex, race, and scalp condition. Samples originated from Caucasians and blacks, both full head and balding, and from Caucasian women. The data indicated essentially no differences among these parameters between the two racial groups or between the sexes. 

Hair lipid plays a critical role in shampoo evaluation [138] and in surface effects of hair, such as frictional effects [155]. 

The ability of anionic surfactants to remove hair lipid is dependent on surfactant structure, concentration, agitation, temperature, time, and other variables including other soils on the hair. In addition, detergents like sodium lauryl sulfate do not penetrate rapidly into hair and should not be expected to remove the same amount of lipid from hair at the same rate as a penetrating Upid solvent like ethanol. 

Under optimum conditions such as in vivo shampooing, anionic surfactants are nearly as effective as chloroform or ether for removing deposited surface lipid. In most of the tests described in the literature, care was taken to exclude conditioning products, containing cationics and cationic polymers or silicones, setting resins, and hard water to provide more control over the experiments. Obviously these variables must be included before we can arrive at a full understanding and a consensus about the efficiency of anionic shampoos for cleaning hair lipid from the surface of hair. 

The total amount of lipid extractable from hair can be as high as 9% of the weight of the hair [32], when a penetrating hair-swelUng solvent like ethanol is used on hair that has not been shampooed for one week. A sizable fraction of the total hair lipid is not removed by shampooing or by extraction with a nonpenetrating, low-boiling lipid solvent like ether. We have... 

This definition of surface lipid by Koch probably provides a high estimate for surface hair lipid. Another definition is the amount of lipid removed by a double application of an anionic surfactant. This latter definition probably provides a more realistic estimate for surface hair lipid. However, if one accepts this latter definition, then the amount of lipid left in hair after shampooing represents internal lipid and may be estimated by solvent extraction (ethanol) after shampooing. 

Table 5-12 summarizes data from an experiment conducted to determine if the quantity of internal hair lipid differs in dry (chemically unaltered hair) versus oily (chemically unaltered) hair. Immediately after shampooing two times with a TEALS shampoo, hair clippings were taken from three oily-haired panelists and three dry-haired panelists and extracted with boiling ethanol. The results suggest similar quantities of internal hair lipid in these six hair samples. 

This test result suggests that the amount of internal lipid in dry and oily hair are virtually identical. Therefore, the primary differences between dry and oily hair lipid are in the amount and the composition of the surface... 

Table 5-12. Amount of hair lipid in oily versus dry hair after shampooing.

The original hair spray lacquers of the 1950s were more difficult to remove from hair than the anionic and neutral polymers of today s hair-setting products. However, no systematic study of the ease or difficulty in removing these ingredients from hair could be found in the scientific literature. Gloor [46] has examined the influence of hair spray on reoiling however, no systematic study of the effects of hair spray on the ease of removal of hair lipid has been reported. 

Analysis of hair lipid reveals that they are very complex, consisting of saturated and unsaturated, straight and branched fatty acids with chain lengths of from 5 to 22 carbon atoms. The difference in composition of lipids between persons with dry and oily hair is only qualitative. Fine straight hair is more prone to oiliness than curly coarse hair. 

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