Introduction
Quercus suber L. and cork origin
Quercus suber L. is an evergreen oak native to the Mediterranean basin, best known for its thick, corky outer bark with outstanding protective properties. Cork consists of a highly specialized tissue that acts as a long-term barrier against mechanical damage, pathogens, dehydration, and environmental stressors (1). Despite its long-standing industrial use, cork remains a botanically and chemically complex material whose biological potential has only recently attracted attention in cosmetic research.
Beyond its structural function, cork contains a distinctive profile of phenolic compounds involved in the plant’s natural defense mechanisms. These polyphenols contribute to the preservation of tissue integrity under environmental stress (2) and are mainly found in the extractable fraction of the bark, where they help modulate reactive species and limit oxidative processes.
Polyphenols are widely recognized for their protective role in plants as well as for their well-documented benefits in skin care. In particular, cork-derived polyphenols have been associated with mechanisms supporting skin structure and function, aligning with the growing demand for botanically derived cosmetic ingredients that combine performance, traceability, and sustainability.
Sustainability and circular economy perspective
Sustainability has become a key driver of innovation within the cosmetic industry, shaping ingredient selection, manufacturing practices, and formulation strategies. In this context, cork from Quercus suber L. represents a renewable and traceable raw material with a low environmental footprint, making it an attractive source of bioactive compounds. The tree’s outer bark regenerates naturally after harvesting, allowing repeated manual extraction at defined intervalsEM_DASHtypically every nine yearsEM_DASHwithout harming tree vitality or ecosystem balance (3).
When properly managed, cork oak forests deliver a range of essential ecosystem services, including soil stabilisation, hydrological regulation, biodiversity conservation, and long-term carbon sequestration. It has been reported that, under optimal conditions, the harvesting of one ton of cork can be associated with the fixation of up to 73 tons of atmospheric CO2 (4), directly linking cork production to positive environmental outcomes.
From a circular economy perspective, cork processing generates significant volumes of by-products such as cork powder and granulates. Rather than being treated as waste, these materials can be upcycled into valuable ingredients. Transforming cork by-products into high-value cosmetic ingredients illustrates a resource-efficient approach that combines environmental responsibility with innovation and performance.
Cork composition
Cork is a heterogeneous plant material primarily composed of structural polymers, including suberin (≈40%), lignin (≈25%), and polysaccharides (≈20%), together with a smaller but biologically relevant fraction of extractives (≈15%). Suberin and lignin provide mechanical strength, hydrophobicity and barrier properties to the cell wall, while polysaccharides contribute to structural rigidity (1). The exact composition may vary depending on factors such as tree age, geographical origin and growth conditions (5).
The extractable fraction is particularly rich in phenolic compounds involved in the cork oak’s natural defense against oxidative and environmental stress (2). Due to their protective role in the plant, these phenolics have attracted interest for cosmetic applications, especially for supporting skin defense mechanisms and limiting oxidative damage.
Polyphenol activity and mechanism of action
Polyphenols are widely recognised for their protective role in plants as well as for their beneficial effects on human skin. Cork-derived polyphenols display strong antioxidant activity, primarily by scavenging reactive oxygen species and interrupting oxidative chain reactions. This activity is especially relevant in the context of skin exposure to ultraviolet radiation and environmental pollutants, both of which contribute to extrinsic ageing through oxidative stress and inflammatory responses (6) (7).
Beyond their antioxidant properties, cork polyphenols have been reported to modulate key biological pathways associated with skin ageing, including the inhibition of matrix-degrading enzymes and the protection of dermal structural components. By helping to preserve collagen integrity, reduce inflammation, and support the skin’s natural defense systems, these compounds contribute to maintaining skin function and structural resilience over time (6) (7) (8) (9).
Overall, the combination of botanical origin, sustainable sourcing, and multifunctional biological activity supports the growing interest in polyphenols derived from upcycled cork as functional ingredients for skin protection and well-ageing cosmetic strategies.
The main objective of the present study is to identify and validate this cork-derived polyphenolic extract as an efficient active ingredient, with its efficacy confirmed in vivo over a two-month period.
Materials and methods
Cork-derived polyphenol extract
Within a circular economy framework, residual cork from Quercus suber L. is valorised through green chemistry processes to obtain a water-based extract rich in polyphenols. This bioactive solution, commercialized as UpCork AOX, contains a complex mixture of cork-derived phenolic compounds. Its detailed polyphenolic profile and extraction methodology were previously presented in a scientific poster (10).
This sustainable extract provides a versatile raw material for cosmetic formulations, combining proven efficacy with minimal impact on formulation colour and sensory profile.
Study design and participants
A randomised, double-blind, intra-individual (hemi-face) clinical study was carried out to evaluate the effects of UpCork AOX on skin hydration and wrinkle appearance over a 56-day period. Assessments were performed at baseline (D0), after 4 weeks (D28), and after 8 weeks (D56).
The test serum contained 3% UpCork AOX (INCI: Aqua (Water), Pentylene Glycol, Polyglyceryl-3 Caprate/Caprylate/Succinate, Glycerin, Quercus Suber Bark Extract, Chondrus Crispus Powder, Algin, Propylene Glycol, Parfum (Fragrance)). The control product consisted of the same base formulation without the active ingredient. Products were applied twice daily (morning and evening) to cleansed skin, with the placebo applied to one hemi-face and the UpCork AOX serum to the contralateral side.
All evaluations were performed under controlled environmental conditions. Volunteers acclimatised for 15 minutes at 23 ± 1DEGREE_SYMBOLC and 45 ± 10% relative humidity prior to each assessment, and all measurements were conducted on clean, product-free skin.
A total of 21 healthy female volunteers aged 35EN_DASH65 years, presenting moderate to very severe facial ageing (grades 2EN_DASH4 on the EibenEN_DASHNielsen photonumeric scale) and dry to very dry skin (<45 A.U.), completed the study. All participants met the inclusion and exclusion criteria, provided written informed consent, and followed a 15-day washout period before treatment initiation.
Figure 1. Effects of Cork Polyphenol Extract on skin hydration
Skin hydration was measured at baseline (D0), after 4 weeks (D28), and after 8 weeks (D56) of treatment with either Placebo Serum or Serum with Cork Extract. Values are shown as arbitrary units (A.U.) (mean ± SEM). *p < 0.05 indicates statistically significant improvement versus baseline. Cork Polyphenol Extract treatment produced a clear and sustained increase in skin hydration.
Skin hydration measurement
Skin hydration was measured on the cheek using a CorneometerREGISTERED_TRADEMARK CM 825 (Courage + Khazaka Electronic GmbH). Five consecutive measurements were performed within a defined 3 × 3 cm region of interest by trained personnel, and mean values were used for analysis.
Wrinkle analysis (3D skin topography and imaging)
Periocular wrinkles (crow’s feet) were assessed using 3D skin topography with the AEVA-HE V4 system (Eotech). Volunteers were positioned on a VisioTOPREGISTERED_TRADEMARK 500 bench to ensure accurate and reproducible alignment at each time point. High-resolution 3D skin maps were generated using active stereometry combined with fringe projection, and a Z-threshold plane was applied to detect wrinkle valleys.
Key parameters analysed included wrinkle number and average perimeter. In addition, high-resolution macroscopic images were captured using CameraScanREGISTERED_TRADEMARK software (Orion Concept), allowing detailed visualisation of wrinkle patterns, three-dimensional region-of-interest maps, and wrinkle detection outputs for each volunteer. All measurements followed standardised acquisition and analysis protocols to ensure consistency and reproducibility.
Subjective evaluation
Treatment efficacy was also assessed through a self-evaluation questionnaire completed at the end of the study. The questionnaire addressed sensory attributes, perceived efficacy, and overall satisfaction, providing insight into potential consumer perception. Responses were rated on a 4-point scale (1 = strongly disagree; 4 = strongly agree), and results were expressed as the percentage of participants reporting satisfaction (scores 3EN_DASH4).
Statistical analysis
Instrumental data were normalised to baseline values and expressed as mean ± SEM. Statistical analysis was performed using two-way ANOVA followed by Šidák’s multiple comparison test to evaluate product, time, and interaction effects. Outliers were identified and excluded using the ROUT method (Q = 0.1%). Questionnaire data were analysed using Sign and Binomial tests, with satisfaction defined as scores of 3EN_DASH4.
Results
Skin hydration
Treatment with Cork Polyphenol Extract led to a marked improvement in skin hydration compared with baseline (Figure 1). After 4 weeks of application (D28), hydration increased by 5.19 A.U. (13.2%), and this effect was maintained at 8 weeks (D56), reaching a 5.39 A.U. (14.8%) increase versus baseline. In contrast, the placebo showed no significant effect, with hydration levels slightly decreasing at both time points (−2.25 A.U. at D28 and −1.55 at D56). These results demonstrate the capacity of Cork Polyphenol Extract to enhance and sustain skin moisture over time.
Well-ageing effect: crow’s feet wrinkles reduction
The anti-ageing potential of Cork Polyphenol Extract was evaluated using 3D skin topography, measuring the number and perimeter of crow’s feet wrinkles. Compared with placebo, treatment with Cork Polyphenol Extract showed a consistent trend toward improvement. At 4 weeks (D28), wrinkle number and perimeter decreased by 10.7% and 11.2%, respectively, and after 8 weeks (D56), reductions of 9.4% and 9.2% were observed (Figure 2). These data indicate a reproducible well-ageing effect, reflected in both wrinkle count and size.
Figure 2. Effects of Cork Polyphenol Extract on crow’s feet wrinkles
Number (A) and perimeter (B) of wrinkles were measured at baseline (D0), after 4 weeks (D28), and after 8 weeks (D56) of treatment with either Placebo Serum or Serum with Cork Extract. Values are expressed as percentage change from baseline and shown as mean ± SEM. Cork Polyphenol Extract treatment demonstrated a clear reduction in both wrinkle number and perimeter compared with placebo, indicating a visible well-ageing effect.
Visual assessment of a representative volunteer confirmed the instrumental findings. High-resolution macroscopic images, 3D region-of-interest (ROI) maps, topography gradients and wrinkle detection maps revealed progressive smoothing of crow’s feet over the 8-week period. Wrinkle detection maps (highlighted in red) show fewer and less pronounced wrinkles at D28 and D56 compared with baseline (D0), illustrating the visible improvement in skin topography with Cork Polyphenol Extract (Figure 3).
Figure 3. Visualisation of crow’s feet wrinkle reduction in a representative volunteer treated with Cork Polyphenol Extract.
(A–D) Representative images acquired at baseline (D0), Day 28 (D28) and Day 56 (D56). (A) High-definition macroscopic images of the region of interest (ROI). (B) Three-dimensional surface reconstruction of the ROI illustrating skin microrelief and wrinkle architecture (µm scale). (C) Colour-coded topographical gradient map showing the distribution and intensity of wrinkle depth (µm). (D) Segmented wrinkle map derived from 3D analysis (µm). These visualisations highlight the progressive smoothing and reduction of wrinkles over the treatment period, illustrating the visible anti-ageing effect of Cork Polyphenol Extract.
Subjective panelist assessment
Self-assessment questionnaires further supported the objective findings. After 8 weeks of treatment, the majority of participants reported visible benefits: 77.3% noticed younger-looking skin, 81.8% perceived their skin as brighter and more radiant, and 77.3% expressed overall satisfaction with the treatment. In contrast, the placebo did not achieve significant acceptance for these attributes. These results highlight both the efficacy and consumer-perceived benefits of Cork Polyphenol Extract, confirming its potential as a well-ageing cosmetic ingredient.
Discussion and conclusion
Polyphenol-rich extracts obtained from upcycled cork by-products of Quercus suber L. represent a sustainable, renewable, and innovative ingredient for modern cosmetic formulations. These extracts align with current industry trends that favor natural, traceable, and environmentally responsible actives. By validating cork by-products, waste is reduced and circular economy strategies are supported, while generating bioactive ingredients with clear functional relevance for skin care.
Beyond their ecological value, cork polyphenols contribute to maintaining skin structure and function by protecting the extracellular matrix and key dermal components. They modulate pathways associated with skin ageing, including inhibition of matrix-degrading enzymes such as collagenases and elastases. This activity preserves collagen, elastin, and other matrix proteins, supporting dermal integrity, barrier function, tissue resilience, and hydration (6) (7) (8) (9).
Previous in vitro studies conducted with this cork polyphenol extract further demonstrate its protective effects. Fibroblasts treated with these extracts showed upregulation of COL1A1 (Collagen Type I Alpha 1 Chain), COL3A1 (Collagen Type III Alpha 1 Chain) and ELN (Elastin), indicating enhanced extracellular matrix synthesis, along with increased expression of antioxidant defense genes SOD1 (Superoxide Dismutase 1), CAT (Catalase) and NFE2L2 (Nuclear Factor, Erythroid 2 Like 2). In keratinocytes, the extracts reduced lipid peroxidation (MDA-TBARS) (MalondialdehydeEN_DASHThiobarbituric Acid Reactive Substances), demonstrating protection against oxidative stress and reinforcing both structural and functional resilience in skin cells.
These molecular effects translated into clinically meaningful outcomes. After 8 weeks of topical application, skin hydration improved significantly compared with baseline, while periocular wrinkle number and perimeter decreased relative to placebo. Three-dimensional skin topography confirmed these improvements, and subjective assessments showed that most participants perceived their skin as younger, brighter, and more radiant. The consistency between in vitro mechanisms and in vivo results underscores the functional relevance of cork polyphenols in supporting skin health through extracellular matrix protection and enhanced dermal resilience.
In conclusion, cork-derived polyphenols are multifunctional, sustainable, and scientifically validated cosmetic actives. We proved in the presented study the extract’s efficacy in vivo and verified it as a compelling solution for modern skin care formulations, meeting consumer expectations for effective products while addressing the increasing demand for environmentally responsible ingredients.
References and notes
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