Grifolin derivatives from Albatrellus ovinus as TRPV1 receptor blockers for cosmetic applications

OBJECTIVE

Blocking the TRPV1 receptor is an interesting approach for the treatment of sensitive skin. Here we investigated the potential of grifolin derivatives from Albatrellus ovinus to act as TRPV1 receptor blockers and their potential to serve as cosmetic active ingredients.

METHODS

Binding characteristics of grifolin derivatives from Albatrellus ovinus were determined in competitive and functional in vitro assays to achieve IC₅₀ values. The TRPV1 receptor was activated in vivo with capsaicin and noxious heat to investigate skin reddening, microcirculation, skin sensations and heat pain thresholds.

RESULTS

Grifolin derivatives extracted from Albatrellus ovinus proved to inhibit the TRPV1 receptor in vitro and in vivo. Besides suppression of the TRPV1 receptor activity upon chemical stimulation with capsaicin, thermal activation was shown to be inhibited as well by application of cosmetic formulations containing 3% Albatrellus ovinus extract. The reduction of stinging and burning sensations as well as reduction of reddening and microcirculation upon irritation with capsaicin or thermal stress proved efficacy in vivo.

CONCLUSION

Grifolin derivatives from Albatrellus ovinus are able to serve as fungal-derived TRPV1 receptor blockers with capability to serve as a cosmetic active ingredient on sensitive skin.

A fundamental investigation into aspects of the physiology and biochemistry of the stratum corneum in subjects with sensitive skin

BACKGROUND

Sensitive skin is a poorly understood skin condition. Defects in stratum corneum (SC) barrier function and/or extrasensory neuronal networks in the epidermis are believed to be involved in the problem.

OBJECTIVES

This study aimed to unravel the relationships between bleomycin hydrolase (BH) and calpain-1 (C-1), pyrrolidone carboxylic acid (PCA) levels, corneocyte maturation, transglutaminase (TG) and plasmin activities on the cheeks of subjects with sensitive skin.

METHODS

Forty-eight female Caucasian subjects, Fitzpatrick skin phototypes II-III, with self-perceived sensitive facial skin, were assessed and underwent a capsaicin reactivity test. Expert grading of skin condition was conducted as well as the measurement of transepidermal water loss (TEWL), skin capacitance, SC cohesion and SC integrity. BH, C-1 and plasmin activities were measured as well as PCA levels, plasmin and TG activity. Differential Nile red and involucrin immunostaining was performed to assess corneocyte maturation and size.

RESULTS

About 52% of the subjects reacted to capsaicin. There were no significant differences between the capsaicin-sensitive and non-capsaicin-sensitive subjects with reference to skin grading, TEWL, skin capacitance and SC cohesion. PCA levels and BH activity were lowest in the capsaicin-sensitive panel (P < 0.05) and were correlated in non-capsaicin-sensitive subjects (r = 0.72). The activity of TG was significantly lower (48%) in the capsaicin-sensitive subjects (P < 0.001) and their corneocytes were less mature and smaller (P ≤ 0.05). SC was estimated to be thinner (6.87 ± 0.28 vs. 8.68 ± 0.26 μm; P = 0.001) in the capsaicin-sensitive subjects with a corresponding shorter SC path length (83.2 ± 4.4 μm and 113.1 ± 4.5 μm; P = 0.001).

CONCLUSIONS

Despite the physiological similarities between the two groups of sensitive skin subjects, differences in their biochemistry were clearly evident. Lower levels of PCA, BH and TG activities together with a greater number of smaller and immature corneocytes indicate inferior SC maturation in the capsaicin-sensitive subjects. The reduced maturation of corneocytes and thinner SC likely contributes to a greater penetration of capsaicin and the associated increased skin sensitivity.

Modified Corneosurfametry as a new accelerated high-throughput ex vivo methodology for predicting cleanser effects towards human skin

BACKGROUND

Corneosurfametry (CSM) was originally developed as a tool to predict irritation potential of cleansers. In this method, surface skin stripped using cyanoacrylate is contacted with surfactants/products, rinsed and stained with toluidine blue and basic fuschin dyes. The intensity of staining increases with increases in irritation potential of surfactant. Our objective was to modify the CSM technique to achieve better control of the tape stripping process. Another objective was to correlate the modified CSM (MCSM) with a traditional in-vivo forearm controlled application test (FCAT) for mildness and to explore its utility to assess the state of corneum after a clinical test.

METHODS

Surface skin cells were tape stripped from forearms of volunteers with D-Squame Adhesive Discs. Discs were treated with a 10% solution of the product in a 96-plate well for 10 min, rinsed, dried and treated with basic fuschin-toluidine blue dye solution, rinsed and dried again. Forearm Controlled Application Test (FCAT) was based on a published protocol. Tape strips obtained after product treatment were also analyzed by the MCSM procedure without additional product treatment.

RESULTS

Mildness/barrier damage assessed from in-vivo FCAT showed a similar ranking to the MCSM results. MCSM, TEWL and Erythema analysis of between-treatment differences showed a good correlation indicating that barrier damage seen in in-vivo studies can be predicted from ex-vivo MCSM studies. MCSM analysis of tape strips after the FCAT study showed that the damage decreased with increase in tape strip number. A moisturizing body wash (MBW) with mild surfactants showed the least damage in all layers. In contrast, harsh dish washing liquid showed significantly higher damage down to several layers. Another MBW with petrolatum in a harsher base showed damage almost similar to that of the harsh dish washing liquid in the surface layers. Thus, the MCSM was able to show underlying damage which would have been normally masked by the deposited petrolatum.

CONCLUSION

The MCSM assay was shown to be a valuable tool for accelerated high throughput evaluation of mildness of surfactants and fully formulated products. MCSM can also be used to assess the state of the corneum after a product treatment.