In vitro: Antimicrobial potential and phytochemical screening of some egyptian aquatic plants

Ethanolic and water extracts of three macrophytes (roots); Echinochloa stagnina (Retz.) P. Beauv; Pistia stratiotes (L.) and Nymphaea lotus (L.) from El-Serw, Dakahlia, Egypt were studied to verify their antimicrobial activities against certain microbial isolates by using agar well diffusion method. Bi-fold dilution technique revealed that all the tested microorganisms showed susceptibility to moderate resistance against E. stagnina ethanolic extract, with minimum inhibitory concentrations (MICs) values varied between 78.125 and 625.00 μg/ml, while its water extract showed antimicrobial activities that were significantly reduced by almost 50% compared to the ethanolic one. On the other hand N. lotus and P. stratiotes water extracts had no activity against all tested microorganisms. The phytochemical screening revealed the presence of some biologically active substances (flavonoides, tannins, sterols and resins) with different concentrations. E. stagnina roots were shown to possess the highest polyphenols contents 3.20 ± 0.01 g/100 g dry wt., moreover some heavy ions as Fe, Mn, Zn and Cu were presist with different concentrations varied significantly (P < 0.05) with plant species and solvent used in extraction.