Determination of sun protection factors (SPFs) using the 'gold standard' invivo method (ISO 24444) is known to be associated with appreciable uncertainty because of experimental variability. Consequently, several invitro methods have been evaluated, that show promising accuracy, reproducibility and correlation with the invivo ISO 24444 method. As a way of eliminating the uncertainties associated with both invivo and invitro methods, a proposal is made here to dispense with the concept of the SPF and instead to introduce a binary system for labelling the protection afforded by topical sunscreens. Phototesting can be either invivo or invitro, with invivo phototesting requiring only a single area of sunscreen-protected skin to be irradiated. Alternatively, a validated invitro method could be employed to determine the threshold protection required for assigning products to the appropriate binary category.

Hair loss is a common issue that affects a large proportion of the population, leading to lower self-confidence and quality of life. Microbial dysbiosis of the scalp has been shown to be associated with several different disorders leading to hair loss. Though several 'microbiome friendly cosmetic treatments are currently on the market, there is no agreement on the best technique for assessing dysbiosis, leading to a lack of scientific rigour for quantifying the effective treatments. To help address this, the association between self-perceived hair loss and the scalp microbiome in an African-American cohort (n = 36) was investigated. Using a self-controlled design, swabs were collected from both 'sparse' and 'normal' scalp sites. The scalp microbiome was characterized via 16S rRNA gene sequencing and a dysbiosis score was calculated based on the proportion of all taxa within the samples. Further, we identified the taxa that contributed most to abnormal or dysbiotic hair sites using a machine learning random forest classifier and a negative binomial mixed-effects model. The dysbiosis index is sensitive to participants' self-assessment of hair loss and interindividual variation. We found a core set of operational taxonomic units (OTUs) assigned to 7 genera that significantly contributed to increased scalp dysbiosis. This study demonstrates that self-perceived hair loss is associated with significant and measurable alterations in the scalp microbiome, making the reported dysbiosis index a practical tool that may be used to assess microbiome changes following cosmetic or medical interventions for hair loss and other microbiome-associated disorders.

This review offers an in-depth exploration of the bioactivities, extraction techniques, formulation approaches and practical uses of naturally derived antioxidants in anti-ageing skincare. A critical analysis of the literature was performed. Extracts from leaves, aerial parts, seeds, peels, fruits and barks exhibit potent antioxidant, anti-inflammatory, photoprotective and anti-tyrosinase activities. Natural-based antioxidants exhibit a wide range of bioactivities as neutralizing free radicals through mechanisms such as metal chelation and activation of cellular antioxidant pathways (e.g. Nrf2/ARE) and anti-inflammatory effects by modulating cytokines like TNF-α and IL-6 and promoting wound healing by stimulating collagen synthesis and bioactive compound production. Extracts from Mucuna species, Magnolia officinalis and Arbutus unedo, for instance, demonstrate anti-ageing efficacy by inhibiting enzymes such as collagenase, elastase and MMPs. Certain fruit and seed extracts provide photoprotection with high SPF values, while others-such as mushroom extracts and essential oils-display potent antimicrobial activity. Their bioactivity is often enhanced through fermentation processes, innovative delivery systems like liposomes, niosomes and polymeric micelles, which improve stability, bioavailability and topical effectiveness. Extraction methods for natural antioxidants-including aqueous, hydroalcoholic, ultrasound-assisted (UAE), fermentation-assisted and alternative solvent (NaDES) techniques-are crucial for recovering and stabilizing bioactive compounds. Emerging green technologies such as supercritical CO2 extraction (SC-CO2), subcritical water extraction (SWE), supramolecular solvents (SUPRAS) and cloud point extraction (CPE) offer sustainable and selective recovery of bioactives with reduced environmental impact. These bioactives address oxidative stress, UV damage and dermal ageing, offering multifunctional applications in cosmeceuticals, pharmaceuticals and nutraceuticals. However, challenges such as photostability, inconsistent bioavailability and regulatory hurdles persist. Future research focusing on synergistic formulations, clinical validation and microbiome-friendly antioxidants will drive their advancement in next-generation sustainable skincare.

Over the last two decades, consumers have been calling for greater transparency for ingredient sourcing and manufacturing practices; therefore, more sustainable alternatives need to be evaluated to meet industry demands. While many organizations give standards for 'clean', 'organic' and 'natural' cosmetic products, sustainable formulations lack standardization and harmonization globally. This study aimed to formulate sustainable lipsticks and moisturizers using resources and standards currently available in the cosmetic industry and compare select sustainable alternatives to a conventional control product. After thoroughly screening ingredients for each product type, five different lipsticks and five batches of moisturizers were formulated and tested for quality, performance and stability characteristics. Pay-off and friction were the most different among the lipsticks, with M4, the lipstick containing sustainable ingredients, having the highest average friction and pay-off at Week 1. As for the moisturizers, spreadability had the largest differences, mostly due to the different emulsifier systems, as expected. Incorporating sustainable ingredients can be challenging, but having quality products while being more environmentally friendly is possible. These case studies are meant to serve as examples for formulation chemists.

Formulators today know that when traditional surfactants and polymers are replaced new problems occur. What was before a 'thickening problem' becomes a 'miscibility problem': the ingredients do not play well with each other anymore. However, the scientific rules are not different for these systems, which can also be understood and controlled. This study was therefore made, focusing on one of the important challenges, namely the phase separation and miscibility problem of polymers and surfactants in aqueous solution in ratios and concentrations of interest as shampoo chassis. There are three main reasons for these problems: (1) Impurities and variability from raw materials, (2) by-products or excess components and (3) high levels of background salt remaining from processing. In this work, the third factor has been investigated to learn when salts should be reduced or counteracted depending on the polymer type used for enabling thickening in the new formula spaces. Thus, the study is fundamental in nature but aims to facilitate communication with suppliers of both surfactants and polymers as well as with colleague formulators. It aims at an increased holistic approach where all ingredients are acknowledged constituents of the system, and even minor additions of simple salts are noted as relevant variables to control to maximize product performance. Visual characterization of phase behaviour and viscosity assessment has been performed where three polymers have been combined with two different sulphate-free surfactants. Emphasis has been put on the effect of background salts. The levels of background salts affect both viscosity and compatibility of the systems investigated, however, to different extents depending on the nature of the materials. It is therefore important to control the levels of salt (often included in the raw materials), and how this affects the nature of the polymer-surfactant interactions, to reach the desired formulation attributes. While prior knowledge based on classical aqueous polymer-surfactant systems was seen to be valid also for newer sulphate-free systems (as long as the salt concentration could be controlled), fully compatible mixtures where viscosity and surfactant concentrations truly meet the levels desired for the end formulation proved difficult to find.

The physicochemical stability of cosmetic emulsions is crucial for successful commercialization and consumer satisfaction. This study presents an innovative protocol that combines rheology, turbidimetry and granulometry to predict emulsion stability more efficiently. Industrial emulsions, including some commercial products, were selected to compare stable and unstable samples with minimal formulation differences. Granulometry, turbidimetry and rheology assessments were used to evaluate physical and structural properties. The collected data were subjected to advanced statistical analysis using experimental design methods. Granulometry, turbidimetry and rheology each effectively distinguished stable from unstable emulsions. Stable emulsions maintained a constant median particle size, while unstable samples exhibited significant increases. Viscosity changes were observed only in unstable emulsions. Turbidimetry showed a Turbiscan Stability Index (TSI) >3 for unstable emulsions and <3 for stable ones. Notably, this combined protocol identified instability as early as 8 days-much faster than standard ISO methods, which require up to 30 days. Integrating granulometry, turbidimetry and rheology with advanced data analysis enables a rapid, reliable and sensitive prediction of cosmetic emulsion stability. This approach overcomes the limitations of traditional testing by allowing earlier detection of instability, improving formulation development, quality control and time-to-market. Future work will assess the protocol's applicability to a wider range of emulsion types.

Niacinamide is a well-established ingredient known for reducing hyperpigmentation by inhibiting melanosome transfer from melanocytes to keratinocytes. This study aimed to explore the potential synergistic effects of niacinamide and low pH in melanogenesis pathways and their impact on skin hyperpigmentation in clinical trials. In vitro experiments were conducted using human melanocyte and/or keratinocyte cultures to investigate the effects of niacinamide at varying pH levels (neutral pH 7 and low pH 2.5-4). Melanin synthesis, melanocyte dendricity, melanosome transfer and melanosome degradation were assessed. Transcriptome analysis was performed to identify gene expression changes in human melanocytes. Additionally, vehicle-controlled facial clinical trials were conducted among Caucasian and Chinese females to evaluate the effects of niacinamide formulations at neutral and low pH. Niacinamide in neutral pH solutions and simple low pH solutions (without niacinamide) did not inhibit melanin synthesis or melanocyte dendricity, as expected. However, niacinamide in low pH solutions significantly inhibited both, indicating a synergistic interaction. Enhanced suppression of melanosome transfer and degradation was also observed, although these effects appeared to be additive to the effects of neutral pH niacinamide. Transcriptome analysis revealed downregulation of genes and pathways associated with melanogenic cytokine signalling, melanin biosynthesis, melanocyte dendricity and melanosome transfer for niacinamide in low pH formulation, but not niacinamide in neutral pH or simple low pH formulations (without niacinamide), further supporting the synergistic effect. A 4-week clinical trial among Caucasian females using 2% niacinamide formulation at pH 2.5 revealed a marked reduction in the appearance of facial spots compared to 2% niacinamide neutral pH or vehicle formulations. Similarly, an 8-week clinical trial conducted with Chinese females using 5% niacinamide formulation at pH 4 demonstrated significantly greater efficacy in both facial spot reduction and skin brightening in appearance than neutral pH niacinamide and vehicle formulations. Our series of invitro and clinical studies revealed groundbreaking findings on the role of pH modulation in enhancing the efficacy of niacinamide for hyperpigmentation reduction. By elucidating the synergistic mechanisms involved, this research paves the way for developing more effective treatments aimed at achieving a brighter and more uniform complexion safely.

ObjectiveThe consortium ALT‐SPF performed an international round robin test to characterize non‐invasive methods as alternatives to the erythema‐based testing of sun protection factor (SPF) according to ISO 24444:2019.MethodsHybrid diffuse reflectance spectroscopy (HDRS) based on a multi‐lambda LED light source uses in vivo reflectance spectra on skin to determine sunscreens in vivo absorbance spectra, which are fused with respective in vitro absorbance spectra measured as thin films transmission as described in ISO 24443:2019. As a part of the ALT‐SPF consortium initiative, a blinded study on 64 samples was performed in four European laboratories. After further improvements of the method, a blinded re‐evaluation based on 16 samples was performed. Five statistical acceptance criteria for new methods were assessed by an independent statistical institute to compare the obtained results to the reference methods for SPF and UVA‐PF.ResultsThe initial ALT‐SPF study 1 showed that the bias criterion was acceptable, while the reproducibility and interlaboratory variability needed further improvement. The re‐evaluation study 2 showed that the reproducibility and interlaboratory variability could be considerably improved. Using only n = 10 volunteers and a bias correction based on the initial ALT‐SPF study 1 data, the SPF results of the re‐evaluation study 2 were close to the acceptance criteria of the ALT‐SPF study with criterion 1 (reproducibility) and only 11% over the limit defined by the performance of the gold standard. The UVA‐PF results were within the acceptance limits for the acceptance criteria, except criterion 3 being in the ‘almost met’ range. The re‐evaluation study indicates that the method has a comparable precision to the gold standard methods ISO 24444 and ISO 24443.ConclusionThis study showed that the LED‐HDRS method is capable of providing reasonable non‐invasive SPF and UVA‐PF results and that the performance shows close alignment to the reference method. Thus, it can be proposed as an alternative method to the current standards ISO 24444 and ISO 24443.