HPLC‐TBARS‐EVSC (high‐performance liquid chromatography–thiobarbituric acid reactive substances–ex vivo stratum corneum) protocol: Selection of the subjects and approach to present the results

Abstract

ObjectiveNowadays, it is recognized the need for improved safety and efficacy protocols to evaluate the human stratum corneum (SC) and its interaction with topical and cosmetic formulations by minimally or non‐invasive methodologies. The aim of our research work was to streamline the HPLC‐TBARS‐EVSC (high‐performance liquid chromatography–thiobarbituric acid reactive substances–ex vivo stratum corneum) methodology, by exploring the results of a group of 18 subjects.MethodsThe study included nine women and nine men aged between 19 and 57 years old with phototypes from II to V. Sites in the forearm of each volunteer were randomly delimited, and the SC was collected by tape stripping. HPLC was used to quantify the MDA‐TBA2 (malondialdehyde–thiobarbituric acid) adduct from the tape‐stripped SC, irradiated and not by an ultraviolet (UV) simulator chamber.ResultsObserving the findings of our present investigation, and the statistical approach applied, the use of the ratio between the treatment site and control would be an adequate strategy to better discriminate and evaluate the results. Additionally, an optimal selection of the volunteers to respond specifically to the purpose of the ex vivo assay also can be considered advantageous.ConclusionsIt seemed that in future studies focusing on the impact of SC UV‐induced lipid peroxidation, determined by the HPLC‐TBARS‐EVSC, the most suitable subjects are females aged less than 35 years old, with phototype II.

Challenging the safety and efficacy of topically applied chlorogenic acid, apigenin, kaempferol, and naringenin by HET-CAM, HPLC-TBARS-EVSC, and laser Doppler flowmetry

“…They demonstrated the capacity to understand and adhere to the test procedures. Consent was obtained through the signing of a consent form, ensuring participant anonymity and the option for voluntary withdrawal at any stage ( Marques et al, 2023 ). The project received approval from the Ethics Committees of the Faculty of Pharmaceutical Sciences, University of São Paulo (protocol 4.885.215; CAAE49880121.0.0000.0067), and Lusófona University (protocol CE.…”

“…Subsequently, aliquots of the samples weighing, approximately, 19.0 mg (delimited area of 9.5 cm 2 ; ratio of 2.0 mg/cm 2 ), containing each of the evaluated polyphenols ( Table 1 ), and the blank gel, were applied to the pre-defined areas. After 2 h of application, the stratum corneum from the site was removed using the tape-stripping technique ( Marques et al, 2023 ).…”

“…The removed strips were irradiated (exposed to UV radiation) using a photostability chamber (Atlas Suntest CPS+) equipped with a xenon lamp (1500 W) and a filter that simulates solar radiation by allowing wavelengths above 290 nm to pass through. Irradiation was conducted at 765 W/m 2 , with a fixed dose and a determined period of 2 h. The temperature was controlled at 35°C to prevent sample overheating ( Marques et al, 2023 ).…”

“…The extraction of the SC by the solvent was carried out using an ultrasonic bath for 15 min. The extracted stratum corneum was evaluated using the HPLC-TBARS-EVSC protocol ( Marques et al, 2023 ).…”

Effects of Investigational Moisturizers on the Skin Barrier and Microbiome following Exposure to Environmental Aggressors: A Randomized Clinical Trial and Ex Vivo Analysis

“…Components of personal skincare products may remain on the skin for weeks and may impact the skin microbiota [ 13 ]. Moreover, new protocols for cosmetic antipollution efficacy evaluation have been reported [ 14 , 15 ]. However, the impact of external agents, as well as environmental aggressors, on the barrier function of the skin and its microbiome (including Staphylococcus and Streptococcus ) is not understood well.…”