Phytochemical Analysis and Antibacterial Studies of Some Yemeni Medicinal Plants against Selected Common Human Pathogenic Bacteria

In traditional medicine, medicinal plants are often used to treat a wide range of infectious diseases in humans. Objective: The aim of this study was to identify the phytochemicals contained in thirteen parts of six Yemeni medicinal plants: Artemisia Judaica, Ficus carica L., Nerium oleander L., Olea europaea, Santolina chamaecyparissus L. and Withania somnifera and to investigate the antimicrobial activity of different concentrations of methanol extracts from the aerial part of the selected plants against S. saprophyticus, Salmonella and E. coli in vitro. Methods: Phytochemical screening was carried out using standard procedures and the antibacterial activity of different extracts of each plant was studied by agar well diffusion method. Results: Phytochemical analysis of the plant extracts revealed the presence of phenols, saponins, essential oils, flavonoids, steroids, tannins, cardiac glycosides and alkaloids. The occurrence of phytochemicals varied from plant to plant. Tannins and phenols were found in all samples, while all other test samples contained at least five of the phytochemicals tested. Almost all extracts were able to inhibit the growth of the bacterial strains, with the exception of the species S. saprophyticus, which was resistant to the methanolic extracts of A. judaica and F. carica L. However, the methanol extract (0.1 g/ml) of S. chamaecyparissus L. and O. europaea showed the largest zone of inhibition (35 mm and 20 mm, respectively) against S. saprophyticus. This is the first report on the antibacterial activity of S. chamaecyparissus L. species against S. saprophyticus. Conclusions: The present screening result shows that the methanol extract of the tested traditional Yemeni medicinal plants exhibits potent antibacterial activity, and the studied plants may represent a new source for the discovery of novel antibacterial compounds for the treatment of drug-resistant human pathogens.