Retinoids in cosmeceuticals

Cosmeceuticals: the evidence behind the retinoids

A wide range of cosmeceutical products are available on the market currently, but evidence to support their use is often lacking in the literature. Specifically, there is a substantial amount of evidence supporting the efficacy of tretinoin in photoaging, but the evidence supporting retinoid-based cosmeceuticals remains sparse. The authors review the current data in the literature related to vitamin A-derived cosmeceutical products and conclude that cosmeceuticals containing retinaldehyde have been shown in large randomized, controlled trials to have the most beneficial effect on aging skin.

Topical retinoids in acne vulgaris: update on efficacy and safety

Topical retinoids represent a mainstay of acne treatment because they expel mature comedones, reduce microcomedone formation, and exert anti-inflammatory effects. The first-generation retinoid tretinoin (all-trans retinoic acid) and the synthetic third-generation polyaromatics adapalene and tazarotene are approved for acne treatment by the US FDA, whereas topical tretinoin, isotretinoin (13-cis retinoic acid), and adapalene are accredited in Canada and Europe. Topical retinoids have a favorable safety profile distinct from the toxicity of their systemic counterparts. Local adverse effects, including erythema, dryness, itching, and stinging, occur frequently during the early treatment phase. Their impact varies with the vehicle formation, skin type, frequency and mode of application, use of moisturizers, and environmental factors such as sun exposure or temperature. The broad anti-acne activity and safety profile of topical retinoids justifies their use as first-line treatment in most types of non-inflammatory and inflammatory acne. They are also suitable as long-term medications, with no risk of inducing bacterial resistance, for maintenance of remission after cessation of initial combination therapy.

Frontiers in sebaceous gland biology and pathology

The development of experimental models for the in vitro study of human sebaceous gland turned down the theory of a phylogenetic relict and led to the identification of several, unknown or disregarded functions of this organ. Such functions are the production of foetal vernix caseosa, the influence of three-dimensional organization of the skin surface lipids and the integrity of skin barrier and the influence on follicular differentiation. In addition, the sebaceous gland contributes to the transport of fat-soluble antioxidants from and to the skin surface, the natural photoprotection, the pro- and antiinflammatory skin properties and to the innate antimicrobial activity of the skin. It is mainly responsible for skin's independent endocrine function, the hormonally induced skin ageing process, the steroidogenic function of the skin as well as its thermoregulatory and repelling properties and for selective control of the hormonal and xenobiotical actions of the skin. Interestingly, sebocytes, at least in vitro, preserve characteristics of stem-like cells despite their programming for terminal differentiation. This review reports on various sebaceous gland functions, which are currently under investigation, including its role on the hypothalamus-pituitary-adrenal-like axis of the skin, the impact of acetylcholine on sebocyte biology, the activity of ectopeptidases as new targets to regulate sebocyte function, the effects of vitamin D on human sebocytes, the expression of retinoid metabolizing cytochrome P450 enzymes and the possible role of sebum as vehicle of fragrances. These multiple homeostatic functions award the sebaceous gland the role 'brain of the skin' and the most important cutaneous endocrine gland.

Randomised, placebo-controlled, double-blind, split-face study on the clinical efficacy of Tricutan on skin firmness

Tricutan is a combination product of herbal extracts traditionally used for treatment of skin conditions, together with dimethylaminoethanol. The effectiveness of Tricutan in improving skin firmness and elasticity in photoaged facial skin was examined in a randomised, placebo-controlled, double-blind, split-face study in 28 women, 34-67 years old. Treatment with Tricutan and placebo was given for 4 weeks. Skin firmness and elasticity was evaluated using the speed of propagation of ultrasound shear waves in the skin as end point (Reviscometer RVM 600). The study was completed by 25 women. The Tricutan treatment resulted in a significantly reduced propagation speed indicating increased firmness. There was no immediate effect by Tricutan application on propagation speed. At self evaluation the women evaluated the treatment effect of Tricutan to be significantly better than the treatment effect of placebo. The clinical evaluation also showed Tricutan to give a significantly better treatment result than placebo. Tolerance to Tricutan was generally good. However, three women did not complete the study because of mild irritative contact dermatitis. The results show that Tricutan can increase skin firmness both objectively and subjectively. Further studies are warranted, especially to investigate if Tricutan can delay the need for surgical face-lift procedures.

Cantilever-Based Sensor for the Detection of Different Chromophore Isomers

We report the use of microcantilevers (MCs) for the detection of three retinoid isomers: 9-cis-retinal, 13-cis-retinal and all-trans-retinal. Detection of synthetic and natural retinoids in topical cosmetic products is important, and their presence can be used to predict reactions with the skin surface. In this study the MC surfaces were functionalized in order to promote the formation of covalent bonds with the chromophores. The lowest mass shift we detected with the functionalized MCs was 1.2 ppt, which is in the range needed by the cosmetics industry. Our results indicate that properly designed and functionalized microcantilevers can be used to construct economical, fast, and sensitive sensors for quality control in cosmetics.