Fucoxanthin and Its Variants from Seaweeds of the Arabian Gulf: Insight into Bioactivity, UV-Protective Properties, Stability and Cosmetic Potential

The pigment profile of seaweeds thriving in the Arabian Gulf, characterized by high temperature, salinity, and high UV index, showed a high proportion of fucoxanthin, indicating its potential role in photoprotection. To investigate this, pure fucoxanthin was isolated from 10 seaweed species that grow under prevailing extreme conditions, and its antioxidant, UV-protective, anti-elastase, anti-collagenase and anti-tyrosinase properties were evaluated. Significant interspecies variation was observed in both yield and bioactivity, with seaweeds surviving extreme summer conditions exhibiting higher fucoxanthin content and enhanced UV-protective properties. Fucoxanthin isolated from Canistrocarpus cervicornis, Feldmannia mitchelliae, Padina gymnospora, and Sargassum angustifolium showed high antioxidant, anti-elastase, anti-collagenase, anti-tyrosinase and UV- protection properties. Structural characterization by NMR revealed variations in the R group among the fucoxanthin isolates. Fucoxanthin derivatives bearing R group –CH2OCO(CH2)4CH3 (hexanoyloxyfucoxanthin) demonstrated superior bioactivity compared to those containing –CH2OCO(CH2)2CH3 (butanoyloxyfucoxanthin) and parent compound containing –CH3 (fucoxanthin), indicating a structure–activity relationship. Stability studies have shown that fucoxanthin remains stable at temperatures up to 70 °C and is resistant to oxidizing agents such as H2O2. However, it is susceptible to high-intensity artificial UV-radiation and is highly sensitive to pH changes above 5. Collectively, these findings highlight the adaptive structural diversity of fucoxanthin from seaweeds of the Arabian Gulf and emphasize the importance of species selection in maximizing bioactivity.