Characterization and topical delivery of phenylethyl resorcinol

Abstract

Objective Phenylethyl resorcinol (PR) has been used widely in the personal care industry as a novel skin lightening ingredient. Surprisingly, there is only limited information describing the physicochemical properties of this active. Therefore, the primary objective of this study was to perform a comprehensive characterization of PR. A secondary objective was to investigate the delivery of this molecule to mammalian skin. Methods Phenylethyl resorcinol was characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and nuclear magnetic resonance (NMR). A new high‐performance liquid chromatographic (HPLC) method for analysis of PR was developed and validated. The log P (octanol water partition coefficient), value, solubility and short‐term stability of PR in a series of vehicles were also determined using HPLC. The evaporation of the selected vehicles was examined using dynamic vapour sorption (DVS). The permeation profiles of PR were investigated under finite dose conditions in porcine and human skin. Results The melting point of PR was determined to be 79.13 °C and the measured log P (octanol water partition coefficient) at 21 °C was 3.35 ± 0.03. The linearity of the HPLC analytical method was confirmed with an r2 value of 0.99. Accuracy of the method was evaluated by average recovery rates at three tested concentrations, and the values ranged from 99 to 106%. The limit of detection (LOD) and limit of quantification (LOQ) were 0.19 and 0.57 μg mL−1, respectively. The solubility of PR in PG, DMI, glycerol was within the range of 367 to 877 mg mL−1. The stability of PR in tested solvents was also confirmed by the 72 h stability studies. From the DVS studies, 70–125% of applied formulations were recovered at 24 h. The permeation through porcine skin at 24 h ranged from 4 to 13 μg cm−2, while the corresponding amounts of PR delivered through human skin were 2 to 10 μg cm−2. Conclusion The physicochemical properties of PR confirm it is suitable for dermal delivery. In this study, propylene glycol was the most promising vehicle for PR delivery to human skin. Future work will expand the range of vehicles studied and explore the percutaneous absorption from more complex formulations.

Topical delivery of niacinamide: Influence of neat solvents

“…No evaporation was evident for the GLY and 1-5P formulations. These findings are consistent with previous reports on the evaporation of neat GLY, DMI, PG and TC(Haque et al, 2017b;Zhang et al, 2019b). To our knowledge DVS has not been used previously to characterise the behaviour of NIA solutions under controlled conditions of temperature and humidity.…”

“…Even though the mechanism by which TC interacts with the skin is not known, its potential to act as a penetration enhancer has been reported for a number of compounds (Lane, 2013). Puglia and Bonina (2008) PG is a hydrophilic solvent that has been used in topical formulations as a solvent for many actives (Lane, 2013;Haque et al, 2017b;Haque et al, 2018;Paz-Alvarez et al, 2018;Hossain et al, 2019;Iliopoulos et al, 2019;Zhang et al, 2019b). In the present work, 5 μL doses of 3 % (w/w) NIA in PG were applied to porcine skin and the percentage permeation after 24 h was 19.2 %.…”

Use of an In Vitro Skin Parallel Artificial Membrane Assay (Skin-PAMPA) as a Screening Tool to Compare Transdermal Permeability of Model Compound 4-Phenylethyl-Resorcinol Dissolved in Different Solvents

“…This means good agreement, as shown by Table 2. Zhang and co-workers [23] have recently reported PER solubility data in propylene glycol (PG), glycerol and dimethylisosorbide (DMI). The reported values for PG are in good agreement with the results found in this study, but the data for DMI and glycerol are significantly different, which may be explained by the differences in their method, in the amount of solid excess or in the crystal form.…”

“…It has suitable UV properties and reasonable solubility in the solvents examined, which made it a good model for the study. A recently published study from Zhang and co-workers [23] has reported a comprehensive characterisation of PER, including HPLC-based logP and solubility and in vitro permeation studies through human and porcine skin. The permeation profile of PER was investigated in finite dose conditions using Franz diffusion cell method and applying PER in three different vehicles.…”

Enhancing trans-resveratrol topical delivery and photostability through entrapment in chitosan/gum Arabic Pickering emulsions

“…Total mass recovery of RSV was checked by considering the mass balance of RSV distributed among the skin, and the donor and receptor compartments [7,28]. At the end of the assay, the Franz diffusion cells were disassembled, and the residual Pickering emulsion (or control sample) in the donor compartment was diluted with 30 ml of fresh receptor fluid solution.…”