Phytochemical and antibacterial profile of five aqueous plant extracts

Abstract

The increasing global interest in plant-derived therapeutics has prompted renewed investigation into medicinal herbs as alternative treatments for infections caused by pathogenic bacteria. The present study investigated the antibacterial effects of five medicinal plants “Nigella sativa”, “Allium sativum”, “Eucalyptus rostrata”, “Hibiscus sabdariffa” and “Syzygium aromaticum” against five clinical bacterial isolates from human patients in Babylon Governorate, Iraq. We used pus, urine, ascitic fluid, stool and blood samples for the isolation of bacterial strains, which comprised Salmonella typhimurium, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis. The antibacterial activity was evaluated by the agar well diffusion method and a qualitative phytochemical screening of each aqueous extract was done. All extracts from the tested plants showed inhibitory activity against the bacterial isolates, with the highest antibacterial effect being obtained from the extract of S. aromaticum against all the tested strains. Activity was observed against all bacteria at 5 mg/mL, except E. rostrata, which had no activity against S. typhimurium. The phytochemical analysis confirmed the presence of most of the extracts, flavonoids, tannins, steroids, alkaloids, saponins, and phenols in most extracts with the exception of flavonoids in E. rostrata, cardiac glycosides in S. aromaticum and terpenoids in H. sabdariffa. These findings support the traditional use of these medicinal plants in the treatment of bacterial infections and highlight their potential as sources of novel antimicrobial agents.