Constituents and Antibacterial Activity of Essential Oil of Nyctanthes arbor-tristis Flower

In this study, the composition and antibacterial activity of essential oil from the flower of Nyctanthes arbor-tristis were determined. The extraction was carried out utilizing the microwave-assisted extraction technique with a short extraction time of 60 min, yielding 0.342% (w/w). Separation and characterization were performed by gas chromatography-mass spectrometric analysis, identifying a total of 34 constituents, including major compounds: phenyl ethyl alcohol (26.1%), eucarvone (18.7%), furfural (10.7%), benzaldehyde (4.8%), phytol (4.7%), and methyl hexadecanoate (3.1%). In the next step, an agar disk diffusion assay was performed to assess the antimicrobial activity of the oil against four different bacterial strains, namely Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa, resulting in zones of inhibition measuring 9, 12, 11, and 9 mm, respectively. However, the broth macrodilution method was carried out against Staphylococcus aureus and Klebsiella pneumoniae, revealing minimum inhibitory concentrations of 2.5 and 5 mg/mL, respectively.