Naturals: The Amazon and beyond

The explosion of cosmetic interest in the use of natural ingredients is nowhere more obvious that in its use of natural oils. John Woodruff explores the use of oils in cosmetics in their widest sense

For the purpose of this feature cosmetic oils will be interpreted in their widest sense to include any liquid that is immiscible with water. Accepting the wider definition cosmetic oils can also be hydrocarbons, fatty acid esters or natural triglycerides. Silicone fluids are also immiscible with water but warrant a separate feature of their own.

Probably still the single most commonly used cosmetic oil is paraffinum liquidum. Also called mineral oil, this consists chiefly of a mixture of hydrocarbons belonging to the methane series and it is obtained from petroleum by distilling off most of the lighter fractions and purifying the liquid residue. The British Pharmaceutical Codex describes it as a colourless, oily, transparent, tasteless, odourless and non-fluorescent liquid. Gaining in popularity are isoparaffins - branch-chained hydrocarbons that have a lighter feel and better spreading properties than mineral oils. Many are available, differentiated by the length of the carbon chain, which ranges from C7-8 to C20-40 in the INCI Dictionary 2004.

Squalane is a hydrocarbon oil obtained by hydrogenation of squalene, which is found in shark liver oil. It is also a by-product of the deodorisation process of olive oil whereby steam is blown through heated oil held under high vacuum. Small quantities of volatile components distil, pulling off at the same time olive oil fatty acids and unsaponifiable components, including squalene, which is then hydrogenated. Chemically the two materials are identical but the majority of consumers would prefer to use squalane from olive oil. It has a specific gravity of approximately 0.81 and is well regarded for its skin feel and ease of spread.

Fatty acid esters

One of the largest group of compounds used in cosmetics are the fatty acid esters. They are the result of reacting a fatty acid with a fatty alcohol and are much used in skin care for their spreading properties and dry oiliness. They reduce the greasy feel of mineral and vegetable oils, giving a lighter, more pleasant skin feel, and they often improve skin penetrating properties because of their solvent powers, allowing them access through the epidermis by intercellular absorption. Many are available and different ones are selected for their differing effects. Making the choice is not simple but guidelines are supplied by their distributors.

Cognis, Degussa, Uniqema and other major suppliers publish a guide to emollient selection and esters feature highly in these guides. The Uniqema Senselect website[1] presents a matrix of properties and the user clicks on the most important, resulting in suggestions of both emollient and emulsifier for achieving the desired properties. Main headings are: pick-up/rub-out/after-feel with sub headings such as firmness/cohesiveness/greasiness/

spreadability/gloss etc. The Degussa method attempts to combine the properties of pour point, polarity, ease of spread and surface tension to the properties of the oils and esters described. That of Cognis explores the cascading theory of emollients whereby a sensorial feel is sought throughout the application of the product.

Polyol fatty acid esters are formed by reacting polyols with fatty acids resulting in materials that are less oily than the fatty acid esters and with improved solubilising properties. A third group is formed by reacting fatty alcohols with organic non-fatty acids. A common use of esters is to improve the solubility of organic sunscreens and the dispersion of inorganic sunscreens and in both cases the active needs to be applied as an unbroken film on the skin. There is a wide selection of oils and esters that not only improve solubility but may also enhance the SPF. Butyloctyl salicylate is a low viscosity oil that solubilises benzopheneone-3 and BMDBM, as well as improving its photostability. Hexadecyl benzoate and butyloctyl benzoate have similar solvent properties and diisopropyl sebacate and diisopropyl adipate are also good solvents that form non-occlusive films and are also soluble in ethanol.

A fascinating presentation by Johann Wiechers was given at the recent SCS Advanced Cosmetic Science course in Bournemouth, UK. Wiechers proposed a method of selection of emollients to enhance skin penetration of the active ingredients based on the polarity of the emollient, the polarity of the penetrating molecule and that of the stratum corneum. Active ingredients need to be solubilised in the formulation but their polarity should match that of the stratum corneum in order for them to leave the oil phase if they are to penetrate the skin.

For skin care, especially for products for younger skin, avoiding the formation of comedones is important. A list found on the web[2] gives a comedone and irritancy score to an extensive list of common cosmetic ingredients, and this does appear to correlate quite well with received wisdom from other sources. As expected, non-oily ingredients seldom appear in the list of comedogenics but the richer natural oils like cocoa butter, coconut oil and wheat germ oil show high scores, as do isopropyl esters and ethoxylated emulsifiers.

Natural obsession

The explosion of cosmetic interest in the use of natural ingredients is nowhere more obvious that in its use of natural oils. At In-Cosmetics, Barcelona 2006, it was obvious that the cosmetic industry's hunger for new varieties continues, with any fruit, seed, nut or husk being squeezed to yield every last drop of natural oil.

The use of oils originally extracted for their nutritional values but now of interest for cosmetic applications is a relatively new trend and part of the holistic pattern of treating the whole body, both inside and out. The major fatty acids commonly found in natural oils are grouped into one of three categories in accordance with their molecular structure. These are known as the Omega 3, Omega 6 and Omega 9 families and research compiled over recent years has provided a lot more information as to their function in the human body. In particular, Omega 3 and 6 fatty acids are the raw materials used by the body to produce a very important series of hormone-like chemicals known as prostaglandins.

Omega 3 fatty acids are used in the synthesis of the PGE3 prostaglandins which regulate the inflammatory response and it is believed to help reduce a number of inflammatory related disorders from which the body suffers, including skin rashes and redness. The body uses Omega 6 fatty acids to help treat dry or damaged skin conditions such as eczema. Omega 9 fatty acids are found in cell membranes, especially in skin tissue, where flexibility is important. Oleic acid in particular is abundant in skin cells and is a very good medium for transferring nutrients across the skin barrier. Oils rich in oleic acid are generally very absorbent and as a result are in wide use in the skin care industry.

Northstar Lipids, in keeping with its concept of topical nutrition, is identifying and selecting oils that contain high levels of functional Omega 3 and 6 fatty acids. The company has recently launched NorOmega PC 369, a proprietary formulation designed to provide an ideal combination of fatty acids and this has been shown to be effective in both emolliency and rejuvenation. It comprises Helianthus annuus (sunflower) seed oil, Camelina sativa oil, Echium plantagineum seed oil, and Ribes nigrum (blackcurrant) seed oil. The ratio of the Omega 3:6:9 fatty acids is 1:1:1.5. Northstar Lipids is also introducing a range of citrus seed extracts in both butter and oil forms. These have been selected due to their unique and highly nutritive lipid content and their potential as both nutritional and skin care ingredients. The company's informative website is well worth a visit.[3]

Amazonian promise

One section of the In-Cosmetics Exhibition focused on ingredients of the Amazonian rainforest with various companies represented. Beraca Ingredients[4] has been in existence in Brazil for 50 years and is a supplier of rainforest materials. It had an interesting selection and although the descriptions should apply to the same oils from other sources the company gave comprehensive details about its main products, from which the following is abstracted.

Açai oil [INCI: Euterpe oleracea pulp oil] is obtained from the seed of the fruit of the Açai palm tree, Oleracea euterpe. The oil has a deep ruby colour and is particularly rich in anthocyanins, essential fatty acids, phytosterols and vitamins. It is also an excellent source of essential fatty acids such as linoleic acid, omega-6 and omega-9, which when applied in cosmetic applications promote nutrition and a healthful aspect to the skin. The phytosterols present in the Açai provide numerous benefits to the human body, acting at the cellular level, regulating the balance and activity of the lipids in the superficial layer of the skin. They are also used in the treatment of dermatitis to stimulate the regeneration process. Beraca suggests that 2% should be added to products with anti-ageing action and to after-sun products. It is certified organic by Ecocert.

Andiroba oil [INCI: Carapa guaianensis seed oil] is obtained from seeds of the Andiroba tree, which grows in the extensive Amazon region. The tree produces fragrant white flowers and the seeds are polyhedral with a curved face. Natives of the rainforest used to pile these nuts in open spaces to let them ferment, allowing the shell to break, and the oil to be drained out of the pulp. They used the oil for the treatment of skin, muscular inflammations, and as a repellent against insect bites, and this latter property makes it of particular interest for natural-based insect repellents.

Brazil nut oil [INCI: Berthollietia excelsa seed oil] is expressed from the seed of the Brazil nut tree, which is enormous, frequently attaining the height of 40 to 50m or higher, and it can be 500 to 800 years old. The refined oil is light yellow, rich in fatty acids such as oleic and linoleic with small amounts of myristic and stearic acid, plus fitoesterol and selenium. It is abundant in vitamins A, B, C and E and is said to act on the cutaneous tissue, promoting a protective layer that blocks evaporation of skin moisture.

Passion fruit seed oil [INCI: Passiflora edulis seed oil] comes from the seed of this clinging vine, which is cultivated mainly in Brazil, Peru and Colombia. The oil is obtained when its seeds are cold pressed, holding approximately 3% of an aromatic brown-reddish oil. The oil is filtered and refined, increasing its quality in terms of colour and odour. The oil comprises about 60% linoleic acid plus

ascorbic acid, beta-carotene, calcium, flavonoids, phosphorous and potassium and is noted for its stability against oxidation. Other oils from the Amazon basin available through Beraca include Buriti oil, rich in pro-vitamin A, Copaiba oil, an essential oil and natural bactericide, and Annato oil, a

natural colouring agent with beta-carotenoids.

Croda is also well known for its oils from the Amazon and, like Beraca, pursues its policy with care for the environment and its indigenous

population. Under the heading Crodamazon, the company provides a range of natural oils developed

by Croda Brazil and based

on the fruits of the Amazon rainforest for use in personal care app-

lications.[5] Working in partnership with the communities located along the banks of the Amazon, it pursues a policy of preserving natural resources and promoting the socio-economic development of the region. The heart of this relationship is the Forest Handling Plan, which must have Government approval, detailing every aspect of the project such as logging the size, position, age and condition of every tree or plant from which the fruit is obtained, to ensure sustainability.

Oils become butters when they are not liquid at ambient temperature but they are still triglycerides. Three butters from Croda are Orbignya oleifera seed oil, a natural oil extracted from the fruit of the babussu tree. It is light in colour and odour and rich in C12 and is semi-solid at ambient temperature. This is recommended for soaps and surfactant systems, hair conditioners and bath oils and baby products. Crodamazon Cupuaçu [INCI: Theobroma grandiflorum seed butter] is a white semi-solid that melts on contact with the skin. It has a high water holding capacity and some UV absorbance properties and is recommended for its anti-inflammatory properties, as a moisturiser and as an emulsion stabiliser. Crodamazon Murumuru [INCI: Astocaryum murumuru butter is a soft white butter that melts at body temperature and is recommended for its rich emolliency and excellent moisturising properties. Crodamazon Pequi is an oil consisting primarily of oleic and palmitic triglycerides, which is an unusual distribution and one that has applications in hair care where tests show it has hair strengthening properties.

Greentech SA is another company with a responsible policy towards its suppliers of natural materials and from the Amazon it offers Inca Inchi Lipactive [INCI: Plukenetia volubilis seed oil]. The oil comes from seeds of the Inca Inchi, a plant growing in the Amazonian area of Peru, where it is farmed according to traditional and organic agriculture methods. Inca Inchi Lipactive is obtained by cold

pressing of seeds followed by mechanical clarification by decantation and filtration and is guaranteed to be organically grown and free from GMO. It is particularly rich in omega-3 and unsaturated fatty acids comprise 94% of its composition. Greentech recommends Inca Inchi Lipactive to soften skin, to improve its lipid balance and to protect it against transepidermal water loss.

Of course the Amazon is not the sole source of interesting oils for cosmetic use. They are sourced worldwide and frequently bring much needed income to third world countries. They provide a use for previously abandoned by-products of agriculture and commerce and investigations often reveal a scientific basis for properties that have long been known by the indigenous populations and are rather disparagingly referred to as folklore.

Website references

1. www.world.uniqema.com

2. www.zerozits.com/Articles/

acnedetect.htm#inglist

3. www.northstarlipids.co.uk

4. www.beraca.com.br

5. www.crodamazon.com