Phytochemical analysis and antibacterial activity of ethanol leaf extract of Vernonia auriculifera Hiern (Asteraceae)
摘要
Medicinal plants of the genus, Vernonia are flowering shrubs in the family Asteraceae, comprise over 500 species distributed across tropical and subtropical regions, particularly in Africa and South America. Many species of this genus are traditionally used to treat various human illnesses due to their diverse bioactive phytochemicals. medicinal properties in treating various health conditions. Vernonia auriculifera, an indigenous Ethiopian medicinal plant locally known as Gujo or Regi (Amharic) and Reji (Afan Oromo), has been conventionally used for wound treatment and other medical uses. This study examined the phytochemical composition and antibacterial activity of the crude ethanol leaf extract of V. auriculifera. Qualitative phytochemical screening the presence of flavonoids, tannins, saponins, terpenoids, and phlobatannins, while alkaloids and steroids were not noticed. Antibacterial activity was evaluated against four clinical human pathogenic bacterial strains (Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli and Shigella boydii) using the disc diffusion method and minimum inhibitory concentration (MIC) assay. The extract exhibited concentration-dependent antibacterial activity with inhibition zones ranging from 7.83 ± 0.12 mm to 16.17 ± 0.07 mm. Gram positive bacteria showed greater susceptibility compared to Gram negative bacteria. The MIC values were 50 mg/mL for Gram-positive strains and 100 mg/mL for Gram-negative strains. Though the antibacterial strength of the extract required relatively high concentrations, the findings indicate the presence of bioactive compounds that may contribute to antimicrobial activity. These conclusions support the traditional use of V. auriculifera and highlight its potential as a source of plant based antimicrobial compounds. Further studies involving quantitative phytochemical screening and bioassay guided fractionation are recommended to identify the active compounds responsible for the observed antibacterial activity.