Phytochemical investigation of Impatiens rothi and Impatiens tinctoria crude extracts and evaluation of their antibacterial activities

Abstract

Medicinal plants remain a critical source of therapeutic agents, with their applications supported by indigenous knowledge and ethnobotanical evidence. This study evaluated the phytochemical profile and in vitro antibacterial activity of Impatiens rothi and Impatiens tinctoria root extracts. Roots collected from Kuyyu District, North Shoa Zone, Oromia Regional State, Ethiopia, were dried, powdered, and extracted using chloroform, ethyl acetate, hexane, methanol, ethanol, and distilled water. Standard phytochemical assays were conducted to detect major classes of secondary metabolites, while antibacterial activity was assessed against gram-positive and gram-negative bacteria using the disc diffusion method. Minimum inhibitory concentration (MIC) values were determined by broth microdilution. Screening revealed alkaloids, flavonoids, tannins, phenolics, saponins, and terpenoids in most extracts, with ethanol and methanol extracts presenting the richest profiles. Ethanol extract of I. tinctoria demonstrated the highest antibacterial activity (19 ± 0.35 mm) against Pseudomonas aeruginosa, comparable to chloramphenicol (26 mm) and vancomycin (20 mm). Conversely, the lowest inhibition zone (7.2 ± 0.28 mm) occurred with hexane extract of I. rothi against P. aeruginosa. The lowest MIC (3.50 mg/mL) was recorded in chloroform extract of I. rothi against Escherichia coli and in aqueous extract of I. tinctoria against P. aeruginosa. Antibacterial effects varied significantly across solvents, highlighting polarity’s influence on extracting bioactive compounds. Findings confirm that Impatiens roots contain diverse phytochemicals with promising antibacterial potential, justifying their ethnomedicinal use. Ethanol and chloroform extracts were most effective. Further phytochemical characterization and toxicity assessments are recommended to validate active constituents and ensure therapeutic safety.