Antiaging and Antioxidant Activities of Upcycled Brazilian Coastal Sargassum sp. Beach-cast for Dermocosmetic Applications

Resumo

Seaweed Sargassum beach-casts are a seasonal phenomenon that regularly deposits tons of algae biomass on beaches, including along the Brazilian coast, where they can have significant environmental and economic impacts. This biomass is often discarded in landfills, contributing to waste accumulation. The present work aims to contribute to the valorization of this biomass and evaluate the dermocosmetic potential of conventional Sargassum extract (CES) and ultrasound-assisted Sargassum extract (UES). In vitro assays evaluated cytotoxicity, antioxidant capacity (DPPH -2,2-diphenyl–1-picrylhydrazyl radical scavenging assay, FRAP - Ferric Reducing Antioxidant Power, and ABTS- 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assay), Total Phenolic Content (TPC), anti-enzymatic activity (inhibition of collagenase, elastase, and hyaluronidase), and photoprotective effects against UVB-induced reactive oxygen species (ROS) in human keratinocytes (HaCaT cells). CES showed minimal cytotoxicity (<5%) in HaCaT keratinocytes suggesting its potential safety for cosmetic use. Pre-treatment with Sargassum extracts significantly reduced ROS production in HaCaT cells, reaching levels similar to ascorbic acid and demonstrating notable photoprotective potential. CES exhibited the highest antioxidant activity in DPPH (30.87% of reduction at 100 µg mL–1) and FRAP (53.17 µmol TE/g) assays, and total phenolic content (TPC, 142.80 ± 24.63 mg GAE/g), indicating strong reducing potential. CES exhibited hyaluronidase inhibition (52.53 ± 1.03% of inhibition at 100 µg mL–1), a noteworthy result given the growing interest in hyaluronidase inhibitors in the cosmetics industry in anti-aging formulations. Overall, these bioactivities, associated with fatty acids, steroids, and phenolic compounds identified in chemical analyses, highlight the dermatological potential of beach-cast algae.