Concentration effects of the UV filter oxybenzone in Cyperus alternifolius: assessment of tolerance by stress-related response

Phytoremediation has been proposed to reduce the load of the sunscreen oxybenzone (OBZ) in the aquatic environment. Despite the proven removal efficiency of this compound, little is known about its influence, particularly oxidative stress on plants. In this study, a short-term incubation of macrophytic Cyperus alternifolius was performed to prove the plant’s ability to withstand the stress. Detached shoots were immersed in medium spiked with different concentrations of OBZ (50, 100, and 500 μM) for 2, 4, and 7 days, respectively. Increased formation of O₂⁻ and H₂O₂ in Cyperus treated with OBZ was characterized by intense colorization following histochemical staining. Alterations of enzyme activities involved in the antioxidative defense system indicate an adaptive response of C. alternifolius to this xenobiotic stress. Quantification of lipid peroxidation reveals that no significant membrane damage occurred during incubation with OBZ. Overall, 50 μM OBZ (tenfold higher than the amount frequently detected in the environment) exhibited low toxic effects. Accordingly, this pilot study provides information on the potential use of Cyperus to remove emerging sunscreen contaminants from water bodies.