Celso Alves1, *, Joana Silva1, Alice Martins1, Roberto Clerque1, Rita M.M. Santos2, Ana S. Mestre2, Ana P. Carvalho2, Márcia I. Goettert3, Rui Pedrosa1, Marco F.L. Lemos1,*
1MARE – Marine and Environmental Sciences Centre, ESTM, Polytechnic of Leiria, Peniche, Portugal; 2Centro de Química Estrutural, Institute of Molecular Sciences, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa; 3Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, Eberhard Karls Universität Tübingen, 72074 Tübingen, Germany;
Due to the growing awareness of skin health, there is a massive demand for new and natural skincare products. Seaweeds have revealed to be a rich source of bioactive compounds with relevant biological properties for dermatological applications. However, after the extraction of bioactive ingredients, the residual biomass corresponds to ca. 99% of the seaweed original weight and maintains its lignocellulosic structure, being still a valuable resource for a broad range of applications. Therefore, this study aimed to develop a sustainable biorefinery process by evaluating the dermatological potential of five extracts obtained from the green seaweed Codium sp., together with the transformation of its residual biomass into biochars. Five independent extracts: water (F1), ethanol: water (F2), ethanol (F3), n-hexane (F4), and ethyl acetate (F5) were obtained, and their antioxidant (DPPH, FRAP, ORAC, TPC), anti-enzymatic (hyaluronidase, collagenase, elastase), cytotoxicity, and anti-inflammatory properties were evaluated. Regarding the antioxidant capacity, the F3 exhibited the highest values of total phenolic content (1.10±0.09 mg EAG/g extract) and FRAP (1.83±0.05 µM FeSO4/g extract), while the and ethyl acetate fraction (F5) exhibited the highest value of ORAC (2,109.30±34.80 µmol Trolox/g extract). This fraction also exhibited the best anti-enzymatic capacity, inhibiting the activity of elastase around 88% at 200 µg/mL. On the other hand, F2 and F3 fractions displayed the highest anti-inflammatory activity significantly reducing the TNF-α release induced by LPS treatment in human whole blood. Biochars were obtained by conventional thermal carbonization of F2 residual biomass in inert atmosphere (TC) and by advanced processes such as hydrothermal carbonization (HTC) and acid-mediated carbonization (AMC). It has an ash content of 27%, which after TC attains 50 % but decreases for advanced carbonization processes (14% for HTC and 9% for AMC). The ashes contain NaCl, KCl and CaCO3. The increase of ash content during TC justifies the higher yield of this procedure (44% versus 24% for HTC and 19% for AMC). The biochar synthesized by HTC has the highest surface area and total pore volume (15 m2/g and 0.034 cm3/g). Data available reveal that the biochars obtained by TC and HTC present 57-62% C and 18-25% O with relevant amount of N (11-14%). The green seaweed Codium sp. extracts possess great potential, while through an integrative biorefinery approach the whole biomass may be used, increasing this biomass value.