Phytochemical analysis and antibacterial activities of Eleutherine bulbosa (Mill.) Urb. extract against Vibrio parahaemolyticus

ABSTRACT

To analyze compounds in Eleutherine bulbosa (E. bulbosa) (Mill.) Urb. extract and to determine its antibacterial capability against Vibrio parahaemolyticus (V. parahaemolyticus). Methods: E. bulbosa bulb extract was preprared using 96％ ethanol by the maceration method. Phytochemical investigation of E. bulbosa extract was analyzed using GC-MS, spectrophotometry and titrimetry methods. The zone of inhibition was identified by the diffusion agar method. The minimum inhibitory concentration and minimum bactericidal concentration were determined using the plate count method. The inhibitory rate against V. parahaemolyticus was determined by the microdilution method. Cellular leakage was evaluated by spectrophotometry and cellular damage was observed by scanning electron microscopy. Results: GC-MS analysis showed the high compound of the E. bulbosa extract was securixanthone E (7-hydroxy-1,2-dimethoxyxanthone). The compound groups also included fatty acid esters, isoquinolines, naphthalenes, and phenolics. The total phenolic content was (2.50 ± 0.00) mg/g, flavonoid (6.61 ± 0.00) mg/g, and tannin (0.03 ± 0.00)％. The greatest zone of inhibition and inhibitory rate were (11.83 ± 0.06) mm and (91.32 ± 2.76)％, respectively, at 10 mg/mL. The minimum inhibitory concentration was 0.156 mg/mL, while the minimum bactericidal concentration was 10 mg/mL. The E. bulbosa extract caused leakage and cellular damage to V. parahaemolyticus. Conclusions: The E. bulbosa extract possesses inhibitory activities against V. parahaemolyticus and causes cellular leakage and damage.