and the tight kink of the hair shaft allows the short hair to re-enter the skin just after exiting the follicular ostia due to the formed sharp tip. This can result in the formation of a pustule, together with a post-inflammatory hyperpigmentation, and/or a scar. Severe razor burn accompanied by ingrown hairs, known as pseudofolliculitis barbae, is common in African people. According to these characteristics it may be summarised that African skin, in comparison with the Caucasian skin, is subject to the following conditions: ■ Acne, which includes pimples, whiteheads, and blackheads; ■ Changes in pigmentation, which causes areas of discoloration; ■ Contact dermatitis, or inflammation that occurs from contact with an irritant or allergen; ■ Eczema, a skin condition that causes itchy, dry, and cracked skin; ■ Seborrheic dermatitis, which appears as scaly patches on the scalp and face.

Azelaic acid as active ingredient for skin care products intented for African people Azelaic acid is a naturally occurring 9-carbon straight-chained saturated dicarboxylic acid (isolated from cultures of Pityrosporum ovale) naturally present in rye, wheat, and barley. A single mechanism of action has not been identified to explain the several beneficial effects of azelaic acid on the skin. In fact, it is well known from the results of several accurate experimental scientific works, topical azelaic acid has anti-inflammatory and antibacterial properties, in addition to comedolytic action. It also competitively inhibits tyrosinase, an enzyme involved in the conversion of tyrosine to melanin, and may then be successfully used to reduce epidermal hyperkeratinization. So this active ingredient, an efficient

antibacterial and anti-proliferative agent, can find its natural application in the formulation of skin care cosmetics for African people. According to the high number of scientific published data, it is an ideal active to treat skin to inhibit the pigment producing enzyme tyrosinase,2

TABLE 1: Characteristics.

INCI NAME and Chemical Identification

Appearance Origin

Azelaic Acid Nonanedioic Acid, CAS: 123-99-9

100% biobased product obtained from Sunflower Oil White to off-white micronised powder

Azelaic acid is obtained by oxidative cleavage of the double bond of oleic chain of the triglyceride of the Sunflower oil, according to the following reaction:

O H3 Manufacturing process H3 C O Pelargonic acid Purity Solubility

R = H, alkyl group 99% minimum

Soluble in glycols, glycerin and alcohols, easily dispersible in polar esters thanks to its unic particle size distribution

Cosmetic Properties

It normalises the microflora on the skin. It has anticomedonal effect by decreasing the amount of hyperkeratinization of the skin. It decreases tyrosinase activity and melanin synthesis to reduce overall skin pigmentation. It induces skin lightening effect. It reduces the appearance of pigmented spots. It is self-preserving It has an excellent safety profile

Applications Recommended Dosage

It can be used in gel-emulsions and both low and high viscosity w/o and o/w emulsions and microemulsions

5 – 15 % by weight it has comedolytic properties, and

may reduce epidermal hyperkeratinization. It has been shown to be effective in the treatment of hyperpigmentary disorders such as chloasma and lentigo maligna, and to have a cytotoxic effect on the human malignant melanocyte.3

lipid fractions, mainly C9–C11 dicarboxylic acids, was demonstrated for the first time in vitro. The interest in azelaic acid, which is a C9-dicarboxylic acid, for treating pigmented lesions thus ensued.4

azelaic acid.8 In addition it does not induce

resistance in Propionibacterium acnes.9 Azelaic acid is then today considered as the

Today there is unanimous

agreement regarding its efficacy and absence of undesirable effects of note. A placebo-controlled clinical study

While treating cases of chloasma

with topical application of an azelaic acid cream, it was observed, and confirmed by patients, that lesions of acne within the areas being treated showed significant improvement. This acid is then used to treat bacterial-

related acne breakouts by attacking the infected pores to help in reducing inflammation and lowering the production of keratin which creates clumps of dead skin cells that trap sebum in skin pores causing more breakouts. With that said, as azelaic acid was more commonly used to treat acne related problems, doctors noticed it had side effects to it which were related to skin lightening. In 1978, the tyrosinase-inhibiting activity of certain


conducted on 52 women with dark or pigmented skin (phototypes IV to VI) suffering from melasma demonstrated the superiority of a cream containing 20% azelaic acid. The women found that their skin was smoother and were thus satisfied overall.5 The anti-inflammatory, anti-keratinising

and bacteriostatic activity of azelaic acid justifies its use in treating diseases such as rosacea or acne.6,7

Over the treatment (of

melasma) period the azelaic acid cream, compared to the hydroquinone one, yielded good or excellent results; no significant treatment differences were observed with regard to overall rating, reduction in lesion size, and pigmentary intensity. Severe side effects such as allergic sensitisation or exogenous ochronosis were not observed with

rising star for anti-acne OTC products. In fact, for the medical treatment of acne vulgaris a variety of preparations are commercially offered with a concentration of azelaic acid of 10-20%. Azelaic acid may be used in the personal

care & cosmetic products, in medical devices and in pharmaceutical products of many countries without concentration limitations. It shows no significant side effects, it has no cytotoxic properties and does not exhibit CMR properties. The major constraint for the use of azelaic acid is its solubility. However, the solubility problem of azelaic acid can be solved using particular solvent systems or using smart formulation techniques. Because of the poor solubility the bio- availability is also limited, but that problem may simultaneously be solved while tuning the solubility. Commercial personal care preparations contain 8-12% azelaic acid, enabling to better control undesired side reactions. OH HO R=H, azelaic acid C O OR O

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