Developmental Toxicity and Stress Response Profiles of a Commercial Aloe vera Extract in Zebrafish Embryos

Despite the widespread use of Aloe vera extracts, their developmental toxicity in aquatic organisms remains poorly understood. This study investigated the effects of a commercial Aloe vera extract on zebrafish embryogenesis, focusing on developmental, morphological, behavioural, and oxidative stress-related endpoints. The 96 h-LC₅₀ was determined to be 0.03%. Embryos at 2 h post-fertilization (hpf) were exposed for 96 h to 0.0004% (LC₁₀) and 0.03% (LC₅₀). Exposure to 0.0004% caused no significant effects compared to controls. In contrast, exposure to 0.03% significantly increased mortality, reduced heart rate, impaired locomotion, and induced multiple malformations. Biochemical analyses revealed alterations in redox-associated biomarkers, characterized by unchanged ROS levels and mitochondrial activity, increased antioxidant enzyme activities (SOD, GPx, GR), and a decreased GSH:GSSG ratio. Lipid peroxidation levels were reduced, while a significant increase in DNA double-strand breaks (DSBs) was observed. Additionally, Nrf2 protein expression was upregulated at 0.03%. Together, these findings suggest concentration-dependent developmental toxicity correlated with alterations in redox homeostasis and genomic stability during early zebrafish development. This study provides new insight into the developmental hazard potential of a commercial Aloe vera extract in an aquatic vertebrate model.