This study was conducted to investigate the activity of crude plants extracts and alumina nanoparticles against Escherichia coli and Staphylococcus aureus by using two methods: agar well diffusion and DNA binding. FT-IR was used to compare the different peaks of the organic group in plant extracts and the plant extracts with an alumina nanoparticles (mix). The results showed that the extracts from three plants had antimicrobial effects against Escherichia coli and Staphylococcus aureus isolates. The mixture of the crude plant extract plus the alumina NP suspension revealed a different effect that ranged between a synergistic and an antagonistic effect. The gel electrophoreses results showed that most of the plant extracts and the mix cleaved DNA with the exception of the alumina nanoparticles alone, which did not have any clear effect.