Antimicrobial activity of the essential oil of Glossogyne tenuifolia against selected pathogens

BACKGROUND Glossogyne tenuifolia ( GT ) is a perennial herb widely distributed in the areas from south Asia to Australia. Many biological effects of G. tenuifolia have been reported; however, the information about antimicrobial activity of the essential oil ( EO ) of the herb remains unavailable. Therefore, the aims of this study were to investigate the antimicrobial activity of the GT‐EO in vitro and food systems, the antimicrobial impact ( AI ) of its individual compounds, and interactive effects of major active compounds (linalool, 4‐terpineol, α ‐terpineol, ρ ‐cymene) on selected Gram‐positive ( S. aureus , L. monocytogenes , S. mutans and S. sanguinis ) and Gram‐negative ( E. coli O157 : H7 , V. parahaemolyticus and S. enterica ) pathogens. RESULTS The minimal microbicidal concentration ( MMC ) of the GT‐EO ranged from 0.75 to 12 mg mL −1 against the test bacteria in vitro . Except for L. monocytogenes, the GT‐EO exhibited more inhibitory effect on the selected Gram positive than against the Gram negative bacteria at the GT‐EO concentrations ≤ 12 mg mL −1 . The interactive effects of major active compounds (linalool, 4‐terpineol, α ‐terpineol, ρ ‐cymene) are additive instead of synergistic via the checkerboard analysis. The bacteria with a microbial load of ca. 10 2 CFU mL −1 in the milk tea could be completely inactivated by the GT‐EO with the MMC of 1.5 mg mL −1 . CONCLUSION ρ ‐Cymene is the largest component in the GT‐EO ; however, it is not the compound predominantly affecting the entire antimicrobial activity of the EO . Instead, 4‐terpineol is the most influential among the test compounds that contribute to the antimicrobial activity of the GT‐EO . © 2014 Society of Chemical Industry