Chaves thermal spring water formulation: Substantiating anti-ageing and anti-inflammatory effects.

BACKGROUND: Thermal spring waters are known for their distinctive mineral compositions, which provide health-promoting, antioxidant, immunomodulatory and skin barrier-reinforcing effects. Historically valued for therapeutic use, these waters have recently gained renewed interest as active components in cosmetic and dermatological formulations. Previous works characterized one of Portugal's most renowned thermal waters from Chaves, revealing its potential as a dermatological base ingredient due to its anti-inflammatory effects, namely the reduction of interleukin-6 in stimulated human keratinocytes. In vivo assays further demonstrated improved skin barrier function, as evidenced by decreased transepidermal water loss and enhanced hydration without disturbing the skin microbiota. OBJECTIVE: Building on these results, a new formulation was developed using Chaves thermal water as both solvent and active ingredient, combined with natural extracts of mallow (Malva sylvestris) and cucumber (Cucumis sativus), and the natural chelating agent sodium phytate to achieve a high natural index. This formulation was compared with the isolated thermal water to evaluate synergistic bioactivities. METHODS: A formulation containing ~80% Chaves thermal spring water, Malva sylvestris and Cucumis sativus extracts and sodium phytate was prepared and characterized. Antioxidant activity (ABTS/DPPH), ferrous ion chelation and inhibition of matrix metalloproteinase-1, tyrosinase and elastase were evaluated. Anti-inflammatory effects were assessed in particulate matter-stimulated HaCaT keratinocytes by measuring interleukin-6 and interleukin-1α (Enzyme-Linked Immunosorbent Assay (ELISA)). Antimicrobial screening against Staphylococcus aureus and Staphylococcus epidermidis was performed using growth curves. RESULTS: This formulation was compared with the isolated thermal water to evaluate synergistic bioactivities. The results revealed a substantial increase in antioxidant capacity, as shown by enhanced ABTS radical scavenging activity and stronger inhibitory effects on ageing-related enzymes, including matrix metalloproteinase-1, tyrosinase and elastase. Anti-inflammatory activity was confirmed through reductions in both interleukin-1α and interleukin-6 levels, the former showing notable improvement compared with the thermal water. CONCLUSION: Overall, this study demonstrates that combining Chaves thermal spring water with synergistic natural extracts yields a multifunctional cosmetic ingredient with amplified antioxidant, anti-inflammatory and anti-ageing properties, offering strong potential for advanced skin care applications.