Cosmetics use of lipids

Ernesto Hernandez Texas A M University, College Station, Texas, Pharmaceutical and Cosmetic Use of Lipids. 

Oils rich in essential fatty acids have been reported to suppress human granulocyte elastase, a tissue-degenerative enzyme that is released when tissue inflammation occurs (59). Oils rich in essential fatty acids, especially from animal origin, have been reported to suppress inflammation as well. Emu oil, for example, has been reported to have superior moismrizing and cosmetic properties in double-blind studies (60). It has also been reported that emu oil increases the proliferation of cells and the growth of hair follicles in laboratory rats (61). As is the case in pharmaceutical applications, the cosmetic properties of lipids synergistically increase when used in combination with phospholipids. Other oils used in cosmetics such as palm, sesame, safflower, borage, and coconut have been reported to increase the trans-dermal properties when used in combination with emu oil. The blend of ethyl... 

The use of fragrant substances has been continuous, and the use of lipids or emollients for anointing is fully documented in historical writings. However, it is probably not justifiable to identify the recipes passed on from antiquity as cosmetics. The compositions based on folklore and mysticism were replaced by more scientifically acceptable products beginning about 1875. The first edition of a handbook of cosmetic chemistry published in 1920 included a foreword noting that scientific cosmetic chemistry did not exist prior to that publication (2). A few years later, texts on cosmetic chemistry and other formularies became available (3,4). 

No discussion of the use of biotransfarmation in lipid chemistry would be complete without some mention of chemical transformation relating to fatty adds. Fatty adds are a major component of the lipid fraction of organisms. They are mainly found as components of triglycerides and phospholipids, although they may occur in smaller quantities as free fatty adds or as esters of other moieties. Fatty adds, either as free adds or as esters, are valuable commodities in the food and cosmetics industries. They may also serve as precursors of a variety of other compounds. 

Dibutyl phenyl phosphate, 11 494 Dibutylphthalate (DBP), 10 430 Dibutylphthalate number, of silica, 22 371 Dibutyl sebacate, cosmetically useful lipid, 7 833t... 

Squalene is also an intermediate in the synthesis of cholesterol. Structurally, chemically, and biogenetically, many of the triterpenes have much in common with steroids (203). It has been verified experimentally that trans-squalene is the precursor in the biosynthesis of all triterpenes through a series of cyclization and rearrangement reactions (203,204). Squalene is not used much in cosmetics and perfumery formulations because of its light, heat, and oxidative instability however, its hydrogenated derivative, squalane, has a wide use as a fixative, a skin lubricant, and a carrier of lipid-soluble drugs. 

One of the major goals of these many investigations of lipids is, of course, a better understanding of the in - vivo behavior of membranes. Beyond studies of binary lipid mixtures, as mentioned above, a further step which is necessary is the incorporation of proteins into the layers. In many respects, this increase in the complexity of the bilayer systems resembles that encountered in the use of synthetic surfactants in "real - world" situations, where blends, rather than single, surfactants are used. Surfactant blends in aqueous solutions are often further modified in use by the solubilization of oily organic compounds, as in the cases of detergency or cosmetic formulation. 

Plant waxes are concentrated on leaves and leaf sheaths and on fruit skins, or in some exceptional cases in the seeds of plants. Most vegetable waxes contain predominantly wax esters plus a variety of other lipid materials, which affect the degree of saturation and other properties of the wax derived from different sources. Most use has been made of plant waxes in the cosmetic sector, but there is increasing interest in the use of plant-derived sterols as dietary supplements to reduce cholesterol formation. 

Lipid nutritional supplements have been in use before the term nutraceutical was coined. Products such as fish oils, shark cartilage, shark liver oil, and vitamins have been in the market since the beginning of the twentieth century. Some of the health claims of these products lacked strict scientific documentation in the past, and their curative properties were mostly anecdotal. However, today there is a better understanding of the biological properties of lipids and their application has extended to combined pharmaceutical and cosmetic fields such as disease prevention and treatment, excipients and coadjuvants, frawi-dermal carriers, and skin emolliency agents. This has led to the development of bioactive cosmetic and pharmaceutical products whose name has recently been coined as cosmeceuticals. 

A wide range of vegetable and animal oils and fats are currently being used as bases and bioactive ingredients in many cosmetic applications. Typical applications of lipids in cosmetics include emollients and specific ingredients for skin care and treatment, hair care, and make-up/decorative products. The type of lipids commonly used in cosmetics include TAGs, emulsifiers, waxes, and structured lipids. The cosmetics industry was more than 25 billion in 2000, and new products are continually introduced in the market. 

The typical properties assigned to cosmetic products include skin moisturization, emolhency and spreadability and coadjuvants to help maintain skin pliability and softness (57). Moisturization is usually considered to be simply occlusivity and humectancy. The role of cosmetics, especially lipid cosmetics besides moisturization, has expanded to multiple effects such as modulation of barrier function, increasing comeodesmolysis and facilitating comeocyte envelope maturation. Specific examples of lipids of interest are listed in Table 2. Examples of lipids used in cosmetics include products derived from olive oil, shea butter oil, mango kernel oil, borage oil, nut oils, and palm and coconut oils. 

Glycerol is a widely used humectant and moisturizer in cosmetics, and considerable research has been done on its effect on the stratum corneum functionality (75). Glycerol was identified as an effective agent in the formation of lipid crystals under conditions of low humidity. The use of alpha- and beta-hydroxy acids on skin desquamation is now well established and widely practiced (76). New lipophilic variants of salicylic acid are reported to affect comeodesmolysis by acting on the whole stmcture of the comeodesmosomes. Alpha-hydroxy acids fractionate the cor-neodesmosomes only (77). 

The accessibility of natural phenolic compounds has opened up the intriguing possibility that one could apply these compounds in foods, cosmetics, and other lipid-containing systems. Rosemary and sage are well known for the highest antioxidant activity among herbs, and their extracts are used in foods because of the strong antioxidant properties. 

One of the components in this olive oil residue that may be of interest for the industry is squalene. Squalene is used as industrial lubricant, and is widely used in several cosmetic applications as a carrier for lipid-soluble components since it is easily adsorbed by the skin (2). Squalene has also been claimed to enhance oxygenation of the blood, facilitate detoxification, strengthen immune system and protect against cancer (3). Traditionally squalene is mainly obtained from shark liver oil (4), which is an unethical use of sharks threatened by extermination and really is not acceptable. 

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