Zeta Aila Marie A. Alea, Lora Mae G. Villegas, Eugene T. Bacolod, Rosalyn P. Alburo
Industrial, healthcare, and agricultural activities have led to increased antibiotic contamination, raising environmental concerns. This study investigated the toxicity of amoxicillin (AMX) in Chanos chanos fingerlings, assessing genotoxicity through micronucleus (MN) and nuclear aberrations (NA) assays and oxidative stress using thiobarbituric acid–reactive species (TBARS) analysis. Fish were exposed to nominal AMX concentrations of 1.746 µg/L (low), 3.453 µg/L (medium), and 5.160 µg/L (high), with samples collected on days 0, 3, 5, 7, and 14. Results indicated a dose- and time-dependent increase in MN and NA frequency, confirming AMX-induced genotoxicity. MN formation progressively increased across exposure groups, with a significant rise from day 3 onward. Similarly, NA frequency correlated with AMX concentration and duration, peaking at 31.33 NA per 1000 erythrocytes in the highest concentration group on day 14. These findings align with previous research linking AMX exposure to DNA damage and oxidative stress. TBARS analysis revealed that malondialdehyde (MDA) levels ranged from 5.29 to 86.31 nmol/mg tissue, with higher concentrations in high-dose exposure groups. More pronounced MDA elevation was observed at higher AMX concentrations, particularly at and above 3.453 µg/L, suggesting increased oxidative damage under elevated exposure conditions. However, because TBARS reflects lipid peroxidation only, these findings should be interpreted as evidence of oxidative membrane damage rather than complete impairment of antioxidant defense pathways. Taken together, the results suggest that AMX exposure may induce both genotoxic effects and oxidative cellular damage in Chanos chanos , with responses becoming more evident at higher concentrations and longer exposure durations. These findings emphasize the need for stricter regulations on pharmaceutical pollutants to mitigate their long-term impacts on aquatic ecosystems. © 2026 The Authors.
Department of Chemistry, University of San Carlos, Cebu City, 6000, Philippines; Biodiversity, Environment, and Natural Resources Research Center (BENRC), Cebu Technological University, Argao Campus, Argao, Cebu, Philippines
