Evaluation of Antioxidant Enzyme Activity and Antibacterial Potential of Eichhornia crassipes Leaf Extracts

Eichhornia crassipes (water hyacinth) is an invasive species of aquatic plant that was assayed for its antioxidant enzyme activity and any antibacterial properties using water and alcohol extracts of leaves and flowers harvested from the Tigris River (Baghdad, Iraq). The water extracts were assayed for glutathione S-transferase (GST) and peroxidase (POX) activities and the presence of heavy metals (iron, zinc, copper) while the alcohol extracts were assayed for secondary metabolites and antibacterial properties against one Grampositive bacterium (Staphylococcus aureus and Bacillus spp.) and two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The results showed that GST (28.123 U/L) and POX (167.323 U/L) activities were significantly higher in the leaves than in the flowers (GST: 8.31 U/L and POX: 91.267 U/L), and this corresponded with the heavy metal accumulation in leaves. For both the samples of alcoholic extract, as well as the two species of bacteria tested, the activity was considerable against the Gram-positive microorganisms at concentrations of 60 and 80 mg/mL, producing inhibition zones of 14- 32 mm, but showed no activity against the Gram-negative bacteria. Various secondary metabolites were present, including alkaloids, terpenoids, saponins, tannins, and flavonoids, which provided the study with its medicinal value. This research on E. crassipes contributes to evidencing its bioremediation potential and application to produce bioactive compounds.