Investigation of UV protection and anti-aging properties of mycosporine-like amino acids in the Moroccan red alga Gracilaria gracilis (Gracilariales, Rhodophyta)

The biological activities of marine algae have attracted the attention of researchers due to their distinctive functional phytochemicals, often absent from terrestrial plants. This study aims to investigate, for the first time, the mycosporine-like amino acids (MAAs) found in the red alga Gracilaria gracilis from the Oualidia lagoon in Morocco. Our research focuses on the extraction and analysis of MAAs, exploring their potential as eco-friendly alternatives to traditional chemical sunscreens. The study underscores the bioactive efficacy of these compounds. Using three distinct solvents for extraction and high-performance liquid chromatography with UV and mass spectrometry (HPLC/UV/MS), we identified five mycosporines: shinorine, palythine-glutamine (bostrychine-A), porphyra-334, palythine, mycosporine-GABA, and one unidentified compound in G. gracilis extracts. MAAs extracts were evaluated for their anti-collagenase and anti-elastase properties, showing IC₅₀ values of 0.095 to 0.20 mg mL⁻¹ for anti-elastase activity and 0.028 to 0.059 mg mL⁻¹ for anti-collagenase activity. The sun protection factor (SPF) of the extracts was determined via an in vitro spectrophotometric method, yielding SPF values ranging from 5.55 ± 0.22 to 9.34 ± 0.59, depending on the solvent used. Additionally, the extracts significantly extended the half-life of chlorophyll under UV radiation, from 11.55 ± 1.2 to 46.21 ± 1.3 min, as measured by a photoprotection assay based on chlorophyll degradation.