Phytochemical screening and evaluation of antibacterial and antifungal activities of Callistemon viminalis cultivated in Iraq.

Callistemon viminalis, a member of the Myrtaceae family, is traditionally used to treat infections, respiratory, and gastrointestinal disorders. This study aimed to investigate the phytochemical profile and evaluate the antibacterial and antifungal activities of C. viminalis leaves cultivated in Iraq. Leaves were collected, dried, and extracted sequentially with hexane and 70% ethanol. Preliminary phytochemical screening revealed the presence of saponins, terpenoids, alkaloids, and flavonoids. The antimicrobial activity of the ethanol extract was assessed using the agar well diffusion method against three Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus sp.), two Gram-negative bacteria (Escherichia coli, Klebsiella sp.), and one fungal strain (Candida albicans). The ethanol extract exhibited notable inhibitory effects, particularly against Gram-positive bacteria and C. albicans, with activity increasing in a concentration-dependent manner. GC-MS analysis of the hexane extract identified key bioactive compounds, including beta-sitosterol and vitamin E. These findings highlight the significant pharmacological potential of C. viminalis leaves and support their traditional use as a source of natural antimicrobial agents. Further studies are recommended to isolate and characterize the active constituents responsible for these effects.