Potential of Adenium obesum flowers extracts as an antibacterial against gram-negative bacteria and gram-positive bacteria

The high number of bacterial resistance to commercial antibacterials requires researchers to create new antibacterials. So far, plant-based antibacterials are still being researched and developed. In this study, the potential of Adenium obesum flower extracts as an antibacterial against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis) were evaluated. A. obesum flowers were extracted using four different solvents based on polarity (ethyl acetate, acetone, ethanol, and water) by the maceration method. The secondary metabolite contents of each extract were tested qualitatively by the phytochemical screening method. Afterward, each extract was tested for its antibacterial potential against Gram-negative and Grampositivebacteria qualitatively (disc diffusion method) and quantitatively (microdilution method). Phytochemical screening showed that each extract contained various secondary metabolites. Antibacterial assay showed that ethyl acetate extract gave the best inhibition against E. coli (IC50 = 571.57 mg/mL) and S. aureus (IC50 = 358.84 mg/mL), while water extract gave the best inhibition against P. aeruginosa (IC50 = 475.15 mg/mL) and E. faecalis (IC50 = 56.99 mg/mL). From quantitative assay,it shows that A. obesum flower extracts inhibited Gram-positive bacteria more effectively than Gram-negative bacteria. This study states that the A. obesum flowers have potential as an antibacterial against Gram-positive and Gram-negative bacteria.