Efficacy of a Dermocosmetic Serum Combining Bakuchiol and Vanilla Tahitensis Extract to Prevent Skin Photoaging in vitro and to Improve Clinical Outcomes for Naturally Aged Skin

Abstract

Background: Skin aging is characterized by slacking and loss of density, especially under ultraviolet (UV) radiation exposure.

Objective: To investigate the beneficial effects of a combination containing bakuchiol (BK) and vanilla tahitensis extract (VTE) to prevent skin photoaging in vitro and to improve clinical outcomes for naturally aged skin.

Materials and methods: Human dermal fibroblasts were treated with active compounds, exposed to an acute dose of UVA and analyzed by confocal microscopy: actin network for morphology, interleukin-8 (IL-8) for inflammation and p16 for senescence. Human skin was used to evaluate chronic UVA-induced glycosaminoglycan (GAG) loss and to assess the benefit of topical application of a BK+VTE serum (Alcian blue staining). An open-label clinical trial was conducted in women applying the serum twice daily for 56 days (n=43). Skin remodeling was assessed by FaceScan^®. Firmness was evaluated through Dynaskin^® and clinical scoring. Skin radiance was also rated on standardized full-face photographs.

Results: UVA induced a significant increase in IL-8 and p16 expression and marked morphological changes in fibroblasts. Treatment with BK or VTE alone prevented both actin network alteration and IL-8 upregulation. Interestingly, BK+VTE demonstrated synergistic protection against IL-8 and p16 overexpression. Serum application prevented GAG loss at the dermo-epidermal junction and increased dermal GAG in UVA-exposed skin explants. In the clinical trial, face ptosis was reduced by 11% on average for 26 responsive subjects and up to 23%. Depth of skin deformation was also reduced by 24% on average for 30 responsive subjects and up to 30%. This firming effect was confirmed by clinical scoring. Radiance was significantly improved by 29% on average for 33 responsive subjects. The serum demonstrated good tolerance/safety.

Conclusion: BK+VTE combination demonstrated anti-aging efficacy and might provide a substantial benefit in the daily care of naturally aged skin in women, through their synergistic effect on inflammaging and senescence.

Keywords: anti-aging therapy; clinical trial; inflammaging; senescence; skin model.

Figure 1

Combination of BK+VTE improves UVA-induced morphology alteration and inflammation in human dermal fibroblasts. Fibroblasts were treated in the presence or absence of VTE or BK alone or in combination. Cells were then irradiated using UVA and analysed by laser scanning confocal microscopy. Pictures show immunofluorescence staining of actin network (green labelling) and interleukin-8 (red labelling) as markers of morphology and inflammation, respectively. Cultures were counter-stained with DAPI to locate the nuclei of fibroblasts (blue labelling). Scale bar = 50 µm.

Figure 2

Quantitative analyses of the effects of BK+VTE combination on IL-8 and p16 immunolabelling. (A) IL-8 quantification from representative pictures obtained from 3 independent donors. Results are expressed in % induction IL-8 mean ± SEM. Statistics were performed using one-way ANOVA completed by a Dunnett’s vs non-treated UVA. ns p>0.05; *p<0.05. % indicates active ingredient protection. (B) p16 quantification from representative pictures obtained from 3 independent donors. Results are expressed in p16 expression arbitrary unit (AU) mean ± SEM. Statistics were performed using a one-way ANOVA completed by a Dunnett’s vs non-treated UVA. ns p>0.05; **p<0.001. % Indicates active ingredient protection.

Figure 3

Combination of BK+VTE improves UVA-induced senescence in human dermal fibroblasts. Fibroblasts were treated in the presence or absence of VTE or BK alone or in combination. Cells were then irradiated using UVA and analysed by laser scanning confocal microscopy. Pictures show immunofluorescence staining of the p16 protein as a nuclear marker of senescence (red labelling). Cultures were counter-stained with DAPI to locate the nuclei of fibroblasts (blue labelling). Scale bar = 20 µm.

Figure 4

Combined BK+VTE, formulated as a serum, improves dermal density in an ex vivo human skin aging assay. Skin explants were chronically exposed to UVA radiation. After each UVA dose, BK+VTE serum was applied topically onto the skin surface. Tissues were then processed by routine Alcian blue staining to evaluate the GAG content as a marker of the extracellular matrix. Pictures were acquired by photon microscopy. Arrows indicate GAG loss at the dermo-epidermal junction. Left panels show low magnification with scale bar at 100 µm. Right panels show high magnification with scale bar at 50 µm.

Figure 5

Illustrative analysis of improvement of ptosis volume by Facescan^® following application of the BK+VTE serum. Blue area refers to decrease in ptosis volume and a more defined face contour, showing a remodeling effect of the product. Ptosis volume decreased by 22.8% from Day 1 to Day 56.

Figure 6

Illustrative results of skin firmness improvement by Dynaskin^® following application of the BK+VTE serum. Cross-section showing the depth of skin deformation from pink color (deep deformation) to green color (no deformation) in the lower part of the cheek. Skin deformation is reduced after 28 and 56 days of treatment as demonstrated by the disappearance of the pink color which shows that skin is firmer. The image below shows another manner to confirm the reduction of skin deformation. From Day 1 to Day 56, skin deformation depth was reduced by 30.4%, and skin deformation volume by 36.7%.

Figure 7

Full-face macrophotographs of radiance evaluation following application of the BK+VTE serum. Pictures show an improvement of radiance after 28 days (+26%) and 56 days (+44%) after twice daily use.