FORMULATING
Arbutin was first used 200 years ago in medicine as an anti-inflammatory and antibacterial agent. It was used particularly for cystitis, urethritis and pyelitis. These uses continue today in natural medicines. It may be used to repress the virulence of bacterial pathogens and to prevent contaminating bacteria, it is also used for treating allergic inflammation of the skin. More recently, arbutin has been used to prevent pigmentation and to whiten the skin. It can also be used to prevent liver spots and freckles, to treat sunburn marks and to regulate melanogenesis. The encapsulation of arbutin constitutes a delivery system to potentialise the effect in time. It is a way to incorporate the hydrophilic arbutin in lipophilic media. Arbutin offers three main properties: whitening effects, anti-ageing effects and a UVB/UVC filter.
Arbutin is a relatively safe skin agent for external use which does not have the toxicity, stimulation, unpleasant odour or side effects of hydroqinone. However, as it is a derivative of hydroquinone, the use of arbutin is restricted in Australia, due to its potential to break down to hydroquinone, or have impurities of hydroquinone from manufacture or storage. The recommended use level is between 1% and 2%.
Bearberry (Arctostaphylos uva-ursi) This plant from the botanical family of the ericacae grows in many areas of the world; in Europe, Northern Temperate Asia and North America. The bush is green and of 15 cm-20 cm high, with leaves dark green on the upper surface, paler beneath, leathery, obovate, spatulate, about 2 cm long and 0.5 cm to 1 cm broad, margins entire, slightly revolute. The scarlet red fruits (drupes) are commonly named bear berries. The part of the plant traditionally used for extraction is the leaf. It has an astringent taste and slight odour.
Vitamin C (L-ascorbic acid) There is an increasing awareness that vitamin C has a wide variety of roles in human health with new therapeutic uses being investigated daily. Among recent discoveries is that vitamin C can play an important role in the health and beauty of skin. Vitamin C in its ascorbyl form has been tested extensively and reported in the Journal of the American Academy of Dermatology to inhibit the production of melanin. When vitamin C inhibits the production of the melanin, a lighter and brighter skin can be achieved in a couple of weeks.
Vitamin C is also required for collagen synthesis, which declines markedly in ageing skin. As we grow older, we suffer
126 PERSONAL CARE April 2012 Liquorice.
diminished micro capillary circulation within our skin, which deprives our skin cells of its supply of vitamin C which it needs for youthful collagen synthesis. The topical application of vitamin C in a skin-penetrating medium can dramatically enhance the availability of vitamin C for collagen production.
Vitamin C regenerates vitamin E in the skin. An antioxidant like vitamin E can only suppress a limited number of free radicals before it runs out of electrons to donate. Vitamin C regenerates vitamin E and enables vitamin E to provide sustained antioxidant protection in the skin’s elastin fibres.
Vitamin C plays a vital role in skin
repair. When your skin is injured, its vitamin C content is used up rapidly in the scavenging of free radicals, and in synthesising collagen to speed healing.
Liquorice
Glycyrrhetinic acid, isolated from Glycyrrihiza glabra (liquorice) is widely used in the cosmetic industry. Liquorice inhibits tyrosinase activity of melanocytes without any cytotoxicity, it has also been shown that UVB-induced pigmentation and erythema can be inhibited by topical application of 0.5% liquorice. The anti- inflammatory properties of liquorice were attributed to inhibition of superoxide anion production and cyclooxygenase activity.
Kojic acid
A fungal metabolic product, kojic acid inhibits the catecholase activity of tyrosinase, which is the rate-limiting,
essential enzyme in the biosynthesis of the skin pigment melanin. Kojic acid is also consumed widely in the Japanese diet with the belief that it is of benefit to health. Indeed, it has been shown to significantly enhance neutrophil phagocytosis and lymphocyte proliferation stimulated by phytohemagglutinin. Melanocytes treated with kojic acid become nondendritic with a decreased melanin content. Additionally, it scavenges reactive oxygen species that are excessively released from cells or generated in tissue or blood. Unfortunately kojic acid is banned from use in Australia due to its potential irritant effects.
Mulberry
This tyrosinase inhibitor was isolated from a plant herbal extract. The plant roots from which paper mulberry was isolated were collected in Korea. The tyrosinase inhibition of paper mulberry was compared to kojic acid and HQ. The IC50
, the concentration
causing 50% inhibition of the activity of tyrosinase, was reported to be 0.396% compared to 5.5% for hydroquinone and 10.0% for kojic acid.
Retinol
The most important natural form of vitamin A. Vitamin A is the first vitamin to be used topically for the treatment of damaged human skin. Today, the term vitamin A is applied to retinol (vitamin A alcohol), retinal (vitamin A aldehyde) and tretinoin (vitamin A acid). Vitamin A stimulates mitotic activity and the production of collagen – what skin is made from. It is now known that the clinical effect obtained with high doses of vitamin A is necessary for normal differentiate and maintenance of epithelial tissues. Especially, retinol is held out as the new great hope for reduction of photoageing skin. Retinol or vitamin A helps to renew and exfoliate the skin, giving a new lighter, beautiful skin.
Azelaic acid
Azelaic acid is a component of grains, such as wheat, rye, and barley. It is applied topically in a cream formulation at a 20% concentration. Azelaic acid is used to treat acne, but there also is research showing it to be effective for skin discolourations. Other research also indicates azelaic acid may be an option for inhibiting melanin production.
PC
In the second part of this article, to be published in June’s issue, Rick Williams will look at commercial skin lightening ingredients, percutaneous absorption enhancers, and product stability
www.Gardenology.org
Raffi Kojian
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