Molecular docking assisted toxicity assessment of Congo Red and detoxification potential of Fraxinus excelsior L. (Oleaceae) biosorbent application

Abstract

The increasing use of Congo Red has raised worldwide concern owing to its detrimental impact on aquatic ecosystems and their inhabitants, prompting increased attention to advanced toxicity assessment studies and sustainable bio-removal practices. In the present study, (i) new insights into Congo Red toxicity were obtained using in vitro model systems and a molecular docking approach, (ii) a sustainable biosorbent from F. excelsior biomass was developed, and (iii) the detoxification potential of the biosorbent was investigated for the first time. CR application up to a concentration of 10 ppm caused a significant decrease in physiological parameters. The germination rate of H. annuus L. seeds were reduced to 60%. Moreover, significant decreases were observed in fresh weight (245 ± 0.7 mg), dry weight (25 ± 0.01 mg), root (1.8 ± 0.1 cm), and shoot lengths (3.2 ± 0.2 cm). Significant alterations in oxidant-antioxidant dynamics, including SOD, CAT, POD, and MDA, were observed after CR exposure. Additionally, increasing the CR concentration from 2 to 10 ppm caused a significant reduction in the mitotic index (14.9%) and an increase in chromosomal aberrations (4.9%) in A. cepa root cells. Molecular interactions between CR and target receptors associated with in vitro parameters (SDP1, PCK1, WRKY transcription factors, B-DNA dodecamer, CAT, POD, and SOD) were determined by molecular docking analysis. FEO biosorbent treatment significantly detoxified CR solutions, and improvements in the values of the tested physiological, biochemical, and cytogenetic parameters were observed. The biosorption process included the zero charge point, pH, initial dye concentration, biosorbent dose, stirring speed, and temperature parameters. The FEO biosorbent removed 92% of the CR from the aqueous solutions. Moreover, the Langmuir isotherm model was found to have a higher R2 value of 0.903. The correlation coefficient of the pseudo-second-order kinetic model (R2 = 0.991) was found to be higher. The process was determined as endothermic and spontaneous according to the ∆G values (- 6.36, - 4.47, - 2.59 and - 0.7 kj/mol) found in the thermodynamic studies. These results indicate that FEO biosorbents have valuable features against CR toxicity in aqueous solutions.