Prospecção da toxicidade do quimioterápico paclitaxel em diferentes espécies de plantas: subsídios para avaliação do risco ambiental

Abstract

Paclitaxel is a chemotherapeutic agent widely used by the population; however, it is classified as an emerging pollutant due to its unregulated disposal into the environment, its detection in environmental matrices, and its potential environmental risk. Considering that soil is a common final destination for emerging contaminants, evaluating its effects on edaphic organisms, such as plants, is crucial for understanding the real ecotoxicological risk. This study aimed to evaluate the cytotoxic and genotoxic potential of Paclitaxel at environmentally relevant concentrations (5, 10, 50, and 100 ngꞏL⁻¹) in bulb roots of Allium cepa, as well as its phytotoxicity in seeds of Daucus carota, Cucumis sativus, and Solanum lycopersicum. Toxicity was assessed using multiple biomarkers, including phytotoxicity analyses (such as germination and initial development), antioxidant defense system analyses (SOD, CAT, APX, GPOX, and DPPH enzymes), oxidative damage (lipid peroxidation TBARS), defense metabolites (total phenolic compounds), cytotoxicity (mitotic index), and genotoxicity (frequency of chromosomal aberrations). The results showed that Paclitaxel caused phytotoxicity in the test species and induced significant oxidative stress in A. cepa, characterized by the inhibition of SOD and CAT enzymes and the depletion of total antioxidant capacity. Consequently, a significant increase in cell membrane damage (TBARS) was observed. At the cellular level, the drug caused strong cytotoxicity, with an approximately 50% reduction in the mitotic index, and high genotoxicity, evidenced by a nearly ninefold increase in the frequency of chromosomal aberrations, such as disturbances, sticky metaphases, bridges, and fragments. It is concluded that Paclitaxel, even at very low concentrations, inhibits plant development and compromises the genetic stability and proliferative capacity of plant organisms, representing a significant ecotoxicological risk for ecosystems exposed to this contaminant.