Skin injuries, from simple cuts to chronic ulcers, affect up to 6% of the population and often result in poor healing due to infection, oxidative stress, and extracellular matrix breakdown. Chronic wounds are particularly challenging, often complicated by biofilm-forming fungi like Candida and dermatophytes. Conventional antifungals are losing efficacy due to resistance and toxicity. Tuberaria lignosa, a herb native to the Iberian Peninsula, has long been used in folk medicine for skin ailments. This study aimed to scientifically evaluate the aqueous extract of its leaves (TLAE) for its antioxidant, enzyme-inhibitory, wound-healing, and antifungal activities.
Methods
Dried T. lignosa leaves underwent aqueous extraction. Phytochemicals were analyzed via UHPLC-HRMS/MS and HPLC-DAD. Antioxidant activity was tested using free radical scavenging assays (DPPH, ABTS), ROS/RNS scavenging, metal chelation, and xanthine oxidase inhibition. Skin-related enzyme inhibition (collagenase, elastase, tyrosinase, hyaluronidase) was assessed. Cytocompatibility and wound healing were tested on human keratinocytes and fibroblasts. Antifungal and antibiofilm activity were evaluated against Candida and dermatophyte strains, including Epidermophyton floccosum.
Key Findings
- Rich in Phenolics:
- TLAE is composed of ~45% phenolic compounds, including ellagitannins (punicalagin: 226.75 mg/g), flavones (vitexin, isovitexin), hydroxybenzoic acids, flavonols, and flavan-3-ols—many reported for the first time in this species.
- Potent Antioxidant Capacity:
- Exhibited very strong antioxidant activity (AAI: 4.56), with IC50 values comparable to Trolox in DPPH and ABTS assays.
- Effectively neutralized ROS (e.g., OH•, O2−•) and RNS (e.g., NO•), chelated Fe²⁺, and inhibited xanthine oxidase (IC50: 27.6 µg/mL).
- Skin-Enzyme Inhibition:
- Strong inhibition of collagenase (58.5% at 200 µg/mL) and tyrosinase (IC50: 67.48 µg/mL); moderate elastase inhibition (IC50: 219 µg/mL).
- No hyaluronidase inhibition detected.
- Safe on Skin Cells + Wound Healing Potential:
- Non-toxic to keratinocytes (up to 100 µg/mL) and fibroblasts (up to 200 µg/mL).
- At 25 µg/mL, promoted fibroblast migration; higher doses showed dose-dependent inhibition.
- Antifungal and Antibiofilm Efficacy:
- Active against dermatophytes: Trichophyton mentagrophytes, T. rubrum, Epidermophyton floccosum, Microsporum canis (MIC: 50–100 µg/mL).
- Fungistatic against Candida krusei (MIC: 1000 µg/mL).
- Inhibited early biofilm formation by E. floccosum, but no effect on mature biofilms.
This is the first comprehensive study of Tuberaria lignosa aqueous extract (TLAE) confirming its traditional use in skin wound care and fungal infections. The extract is rich in bioactive phenolics—particularly punicalagin, isovitexin, and vitexin—which account for its potent antioxidant, anti-collagenase, anti-tyrosinase, and antifungal actions. It is cytocompatible and promotes early wound healing at lower doses. The findings also highlight the extract’s novel antibiofilm properties. Future work should explore mechanisms of action, batch variability, and clinical translation for skin therapeutics and cosmeceuticals.
Link to the study: https://www.mdpi.com/2223-7747/14/15/2299
