The influence of personal care products on ozone-skin surface chemistry.

Personal care products are increasingly being marketed to protect skin from the potentially harmful effects of air pollution. Here, we experimentally measure ozone deposition rates to skin and the generation rates and yields of oxidized products from bare skin and skin coated with various lotion formulations. Lotions reduced the ozone flux to the skin surface by 12% to 25%; this may be due to dilution of reactive skin lipids with inert lotion compounds or by reducing ozone diffusivity within the resulting mixture. The yields of volatile squalene oxidation products were 25% to 70% lower for a commercial sunscreen and for a base lotion with an added polymer or with antioxidants. Lower yields are likely due to competitive reactions of ozone with lotion ingredients including some ingredients that are not intended to be ozone sinks. The dynamics of the emissions of squalene ozonation product 6 methyl-2-heptenone (6MHO) suggest that lotions can dramatically reduce the solubility of products in the skin film. While some lotions appear to reduce the rate of oxidation of squalene by ozone, this evidence does not yet demonstrate that the lotions reduce the impact of air pollution on skin health.

The potential prebiotic effect of 2-Butyloctanol on the human axillary microbiome.

OBJECTIVE: The human axilla is colonized by a wide array of microorganisms that contribute to the generation of body odour. Traditional antiperspirant/deodorant products are used to reduce perspiration in the axillary region and to treat or prevent the growth of bacteria in this region, thereby reducing or eliminating body odour. However, they may also compromise the axillary microbiome balance. The personal care industry has been seeking new ingredients, such as prebiotics or probiotics, to maintain a healthy balance of the skin microbiome by inhibiting odour-causing bacteria, whilst maintaining and promoting the growth of good bacteria. The aim of this study was to investigate the prebiotic effect of a skin-care ingredient, 2-butyloctanol, on the human axillary microbiome. METHODS: An in vitro growth inhibition/promotion assay was performed to test whether 2-butyloctanol inhibited or promoted skin bacterial growth. The impact of 2-butyloctanol on the axillary microbiome was also investigated in a human clinical study using 16S rRNA gene sequencing. RESULTS: In-vitro testing showed that 2-butyloctanol significantly inhibited the growth of corynebacteria at concentrations of 0.64%, 2.56% and 5.12%, whilst the growth of Staphylococcus epidermidis was maintained at the same concentrations. The impact of 2-butyloctanol on the axillary microbiome was also validated in a human clinical study. A deodorant roll-on product containing 3% of 2-butyloctanol significantly reduced the relative abundance of corynebacteria, whilst increasing the relative abundance of Staphylococcus and the ratio of Staphylococcus to corynebacteria after four weeks of application, whilst the placebo showed no significant change. CONCLUSION: For the first time, it was demonstrated that 2-butyloctanol had a potential prebiotic effect on the human underarm microbiome in inhibiting odour-causing Corynebacterium, whilst maintaining and promoting skin-friendly Staphylococcus in both in-vitro and in-vivo studies. Therefore, 2-butyloctanol could be used as a potential prebiotic ingredient in personal care products for underarm microbiome protection.

OBJECTIF: les aisselles humaines sont colonisées par un large éventail de micro-organismes qui contribuent à la génération de l'odeur corporelle. Les produits antitranspirants/déodorants traditionnels sont utilisés pour réduire la transpiration et traiter ou prévenir la croissance des bactéries dans la région axillaire, réduisant ou éliminant ainsi l'odeur corporelle. Cependant, ils peuvent également compromettre l'équilibre du microbiome axillaire. Le secteur des soins personnels recherche de nouveaux composants, tels que des prébiotiques ou des probiotiques, afin de maintenir un équilibre sain du microbiome cutané, en inhibant les bactéries responsables des odeurs tout en maintenant et en favorisant la croissance des bonnes bactéries. L'objectif de cette étude était d'étudier l'effet prébiotique sur le microbiome axillaire humain du 2-butyloctanol, un composant indiqué dans les soins cutanés. MÉTHODES: un test in vitro d'inhibition/de promotion de la croissance a été mené afin de déterminer si le 2-butyloctanol inhibait ou favorisait la croissance bactérienne cutanée. Les effets du 2-butyloctanol sur le microbiome axillaire a également fait l'objet d'une étude clinique chez l'homme qui reposait sur le séquençage du gène ARNr 16S. RÉSULTATS: les tests in vitro ont montré que le 2-butyloctanol inhibait significativement la croissance des corynébactéries à des concentrations de 0,64 %, de 2,56 % et de 5,12 %, tandis que la croissance de Staphylococcus epidermidis se maintenait aux mêmes concentrations. Une étude clinique chez l'homme a également permis de confirmer les effets du 2-butyloctanol sur le microbiome axillaire. Un produit déodorant à bille contenant 3 % de 2-butyloctanol a réduit significativement l'abondance relative des corynébactéries, tout en augmentant l'abondance relative de Staphylococcus et le rapport entre Staphylococcus et les corynébactéries après quatre semaines d'application, tandis que le placebo n'a montré aucun changement significatif. CONCLUSION: pour la première fois, des études in vitro et in vivo ont démontré que le 2-butyloctanol avait un possible effet prébiotique sur le microbiome axillaire humain, en inhibant Corynebacterium, la bactérie responsable des odeurs, tout en maintenant et en favorisant la croissance de Staphylococcus, une bactérie respectueuse de la peau. Par conséquent, le 2-butyloctanol pourrait servir de possible composant prébiotique dans les produits de soins personnels pour la protection du microbiome axillaire.

Professional-Grade TCA-Lactic Acid Chemical Peel: Elucidating Mode of Action to Treat Photoaging and Hyperpigmentation.

Chemical peeling is usually performed by dermatologists, plastic surgeons, and aestheticians for the treatment of photo-aged skin, dyspigmented skin, skin prone to acne eruption, and pre-cancerous skin lesions, etc. In this research paper, we report our investigative findings to understand the mode of action of a commercial professional chemical peel to treat hyperpigmented and photoaged skin. In the in-vitro experiments, we found that the peel inhibits enzymes that are responsible for degradation of collagen and elastin, and the production of melanin pigment. It was surprising to observe that trichloroacetic acid (TCA), which is considered a workhorse of chemical peels for its cauterant action, could synergistically promote the inhibitory action of lactic acid. The rationale behind this synergistic effect could be the conformational change in TCA from linear structure to ring-like structure, which was elucidated through sequential docking using Rosetta software. The in-vitro results on collagen and elastin were corroborated by up-regulation of COL1A, COL3B, fibronectin, and elastin gene expression from 3D human skin equivalents treated with the peel. The findings were further validated through ex-vivo testing on human skin biopsy. The peel significantly inhibits the production of total melanin, and ameliorates photo-damage that was evident through repair of the collagen in the skin exposed to a biological effective dose of UV daily light (6 J/cm2). These research findings have implications for product developers and users (dermatologists, plastic surgeons, and aestheticians) in improving safety and efficacy of chemical peels/peeling.