Fucoxanthin from the crude extract of Turbinaria conoides and its antioxidant, antibacterial, and toxicological effects.

In this work, fucoxanthin (Tc-fuco) was isolated from the crude extract of T. conoides (Tc-cru), and evaluated its antioxidant, antibacterial, and toxicity studies for biomedical applications. Characterized using TLC, UV-Vis, FTIR, HPLC, LCMS and NMR analyses confirmed the pigment nature and functional groups, with a yield of 0.2068 mg/g FW. The Tc-cru performed less antibacterial activity than the isolated Tc-fuco; inhibition zones (mm) for Tc-cru were 6 (P. aeruginosa), 6.2 (S. aureus), 5 (E. faecalis), 5.5 (E. coli), whereas Tc-fuco produced larger zones (mm) of 9 (P. aeruginosa), 7.5 (S. aureus), 8 (E. faecalis), and 8.5 (E. coli), respectively. In DPPH, and H2O2 assays, Tc-fuco demonstrated potent antioxidant effects with IC50 values of 44.61 and 43.03 µg/mL, respectively. This outperformed the crude extract (Tc-cru), which exhibited IC50 values of 60.36 and 75.18 µg/mL, respectively. Light and confocal microscopy images displayed a dose dependent reduction in biofilm formation relative to control groups. Furthermore, the toxicity of Tc-cru and Tc-fuco in A. salina was assessed following 24 hours exposure. Biochemical responses evaluated at 48 hours, confirmed the nontoxicity and sustainable development of tested doses. These findings suggest that the isolated fucoxanthin might be utilized in production of new antibacterial drugs.