86 NATURALS
variety of personal care products (also COSMOS/ ECOCERT approved), providing not only lightening/brightening action but all together important benefits (Table 1).
Azelaic acid in cosmetics products with skin disorders Thanks to its antibacterial abilities, Azelaic acid is detrimental for particular organisms such as Propionibacterium acnes and Staphylococcus epidermidis. These bacteria, which reside in the sebaceous glands present in the dermis,4
are
held responsible for acne vulgaris. Azelaic acid acts specifically on
P.acnes and S.epidermidis, without affecting most other bio-organisms. It also decreases the production of keratin, required for the growth of
P.acnes;
P.acnes destroys the wall of the sebaceous glands to obtain the required nutrients, more particularly proteins that are hydrolysed into the corresponding amino acids.5 Treatment for acne include benzoyl
peroxide, salicylic acid, α-hydroxy acids, retinoids, antibiotics (doxycycline, clindamycin), nicotinamide (vitamin B3) and keratolytic preparations.6
Benzoyl peroxide and salicylic
acid especially are currently under scrutiny. The FDA issued the statement: ‘The Food
and Drug Administration (FDA) is warning that the use of certain acne products containing the active ingredients benzoyl peroxide or salicylic acid can cause rare but serious and potentially life-threatening allergic reactions or severe irritation. An active ingredient is the component that makes the medicine effective against the illness or condition it is treating’.7 Side effects are instead virtually absent
with azelaic acid. Azelaic acid is believed to function on the basis of its antimicrobial activity and/or normalisation of keratinisation (the process by which epithelial cells mature as they move towards the skin surface and are then desquamated). The European Union considers azelaic acid as a cosmetic ingredient that can be applied without concentration restrictions. In the US, azelaic acid is FDA approved for the treatment of acne and rosacea. A variety of products containing 10-25% azelaic acid are commercially available. The effect of a topical acne treatment made
with azelaic acid on the transmembrane pH gradient (ΔpH) of
P.acnes and S.epidermidis was studied in vitro at external pH values found on human skin (pH 4-6). The results indicate that the antibacterial activity of azelaic acid is associated with the perturbation of intracellular pH of the organisms. The effects of topically applied azelaic acid
were studied with 47 individuals (12 with normal skin, 15 with seborrheic skin and 20 suffering from acne).8
Topical application of a 20% azelaic
acid cream significantly reduced the number of lesions with the acne patients, but failed to induce clinically detectable changes in normal or seborrheic epidermis. In vitro, azelaic acid exerted marked time- and dose-dependent anti-proliferative cytostatic effects on cultured keratinocytes, with a 50% inhibitory dose of 20 mMol. This is indicative of the anti-keratinising properties of azelaic acid, displaying anti-proliferative
PERSONAL CARE October 2023
THE BENEFITS OF COSMETIC-GRADE AZELAIC ACID Benefits/Claims
Effective in the treatment of oily and impure skin.
Provides a progressive lightening / brightening effect for a more uniform complexion
Reduces skin pigmentation and colour irregularities such as age spots, revealing smoother, brighter, more supple skin with fewer irregularities
Improving the appearance of sun damaged skin and fighting skin ageing
Enhancing performance of certain topical over-the-counter, drugs or quasi-drugs and prescription products
cytostatic effects on keratinocytes and modulating the early and terminal phases of epidermal differentiation.9 Rosacea, also named ‘the curse of the
Celts’, mostly affects people from northwestern descent. It is a chronic condition characterised by facial redness (erythema). Without treatment, rosacea worsens in time; treatment with antibiotics is counter-effective and their use is being discouraged. The causes of rosacea are not yet clear, although it has been concluded that allergies may play a significant role. Also weather conditions (high sun intensity, cold/ warm weather, wind, frost) may contribute to episodes of flushing. Also a disturbed balance of the intestinal flora is considered as a cause for rosacea. Azelaic acid has been demonstrated to
be effective for the treatment of rosacea. It is available as a 20% cream or a 15% hydrogel. It reduces inflammatory lesions and erythema in rosacea patients and also inhibits neutrophilic reactive oxygen species (ROS). In the neutrophil system, azelaic acid inhibits the ROS formation in a dose-dependent manner, markedly decreasing the number of free radicals. In the xanthine-xanthine oxidase system,
none of the ROS generated was decreased by any dose of azelaic acid, indicating that azelaic acid does not scavenge generated ROS, but rather inhibits cell metabolism, possibly by decreasing enzymatic activity within the cell membrane. In a study by Akamatsu,10
it was
found that NADPH oxidase activity on the neutrophil surface membrane, which mediates the neutrophilic production of most ROS, is effectively inhibited by lower concentrations of azelaic acid.
Azelaic acid as skin lightening/ whitening agent In 1978, the tyrosinase-inhibiting activity of certain 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.11 Azelaic acid depigmenting activity appears
to be mediated by inhibition of mitochondrial oxidoreductase activation and DNA synthesis, although it is also a competitive and reversible
Applications
Moisturizing skin creams, serum and lotions, cleansers and toners. Men’s skincare products
Moisturizing skin creams, serum and lotions, cleansers and toners. Men’s skincare products
Creams, serums, lotions, cleansers, and toners designed to reduce the signs of ageing. Whitening products, skin peeling products. Men’s skincare products (also after-shaving products)
Moisturizing skin creams, serum and lotions, Moisturizing skin creams, serum and lotions. Men’s skincare products
Acne treatment combinations, skin lightening / whitening combinations, sunscreen combinations. Men’s skincare products
inhibitor of tyrosinase. Its lightening effect appears to be selective and most apparent in highly active melanocytes, with minimal effects in normally pigmented skin.12 About azelaic acid, there is unanimous
agreement regarding its efficacy and absence of undesirable effects of note. It is a natural skin bleaching agent and a naturally effective lightener for the skin. It has the advantage of giving a paler skin, naturally. Many studies are available today to show this ingredient is able to lighten complexion. A placebo-controlled clinical study
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 their skin was smoother and were thus satisfied overall.13
The anti-inflammatory, anti-
keratinizing and bacteriostatic activity of azelaic acid justifies its use also in depigmenting skin with diseases such as rosacea or acne.13,14 In a six-month study on 132 Asian women with melasma, a mean four years of treatment with azelaic acid caused both a greater lightening of pigmented lesions and a reduction in lesion size.15
In another study, azelaic acid
was applied at concentrations of 15% or 20% twice daily for three to 12 months.16
Clinical and
histological resolution in facial lentigo maligna was obtained and it was successful in treating rosacea, solar keratosis and hyperpigmentation associated with burns and herpes labialis. In conclusion, azelaic acid is generally well tolerated and can be used for extended periods. Considering here are different ways to
combat hyperpigmentation, sometimes, It may useful also to combine different whitening / lightening active agents in the same cosmetic formulation. This was demonstrated by a study sponsored by Pierre Fabre Dermocosmetique,17 based on the use of a combination of azelaic acid with oligopeptide-68 and glycolic acid, where the efficacy of this active combination in a dermo-cosmetic serum on reducing actinic lentigo and improving photoageing was evaluated. The aim of this monocentric open-label
clinical study was to assess the clinical and instrumental efficacy and tolerability in use conditions of a serum containing a complex
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