A potential biopreservative: Chemical composition, antibacterial and hemolytic activities of leaves essential oil from Alpinia guinanensis

Abstract

Essential oils (EOs) have attracted great interest for their potential as safer biopreservatives. Alpinia guinanensis is widely used as an ornamental plant, food spice and folk medicine in China. This study aimed to explore the leaves EO of A. guinanensis as a potential biopreservative. The chemical composition, antibacterial activity, mechanism and hemolysis of the leaves EO were studied for the first time, respectively. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC–MS) indicated the major constituents were 1,8-cineole (43.11%), α-phellandrene (17.17%) and β-pinene (14.51%). The leaves EO demonstrated broad-spectrum antibacterial activity against tested foodborne pathogenic bacteria (Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli) with minimum inhibitory concentration (MIC) ranging from 2.5 mg/mL to 5.0 mg/mL and diameter of inhibition zone (DIZ) from 16.5 mm to 23mm. The DIZ of the leaves EO (23.0 mm) against Staphylococcus aureus was notably larger than that of antibiotic streptomycin (18.3 mm). Scanning electron microscope (SEM) observation and cell permeability assay indicated the leaves EO increased membrane permeability, resulting in bacteria lysis and leakage of intracellular electrolytes. The leaves EO caused rapid increase in the electric conductivity in the first 2h and the value reached 66.5% after 7h. This mechanism of the leaves EO differed from the antibiotic streptomycin which inhibited protein synthesis. The low hemolytic rate (below 1%) of the leaves EO on human red blood cells (hRBCs) further suggested its safety. In general, the leaves EO of A. guinanensis may provide a natural and safe biopreservative in food industry.