Antibacterial Action of Jineol Isolated from Scolopendra subspinipes mutilans against Selected Foodborne Pathogens

Abstract

This study was undertaken to assess the antibacterial potential of 3,8-dihydroxyquinoline (jineol) isolated from Scolopendra subspinipes mutilans against selected foodborne pathogens Escherichia coli O157:H7 and Staphylococcus aureus KCTC-1621. Jineol at the tested concentration (50 μL; corresponding to 250 μg/disk) exhibited significant antibacterial effects as a diameter of inhibition zones (11.6-13.6 mm), along with minimum inhibitory concentration (MIC) and minimum bactericidal concentration values found in the range of (62.5-125 μg/mL) and (125-250 μg/mL), respectively. Jineol also exhibited significant antibacterial effects as confirmed by the reduction in bacterial cell viabilities, increasing release of potassium (K⁺) ions (650 and 700 mmole/L) and 260 nm materials (optical density: 2.98-3.12) against both the tested pathogens, E. coli O157:H7 and S. aureus KCTC-1621, respectively. Moreover, changes in the cell wall morphology of E. coli O157:H7 and S. aureus KCTC-1621 cells treated with jineol at MIC further confirmed its inhibitory potential against the tested pathogens, suggesting its role as an effective antimicrobial to control foodborne pathogens.

Keywords: antimicrobial effect; foodbrone pathogens; jineol; scanning electron microscopy.

FIGURE 1

Chemical structure of jineol isolated from Scolopendra subspinipes mutilans.

FIGURE 2

Effect of jineol on the viability of the tested pathogenic bacteria of S. aureus KCTC1621 (A) and E. coli O157:H7 (B). Control without treatment. Data are expressed as mean ± SD (n = 3). Values in the same column with different superscripts are significantly different according to Duncan’s Multiple Range Test (P < 0.05).

FIGURE 3

Effect of jineol on the release rate of extracellular K⁺ ions from S. aureus KCTC1621 (A) and E. coli O157:H7 (B). Data are expressed as mean ± SD (n = 3). Values in the same column with different superscripts are significantly different according to Duncan’s Multiple Range Test (P < 0.05).

FIGURE 4

Effect of jineol on the release rate of 260-nm absorbing material from S. aureus KCTC1621 (A) and E. coli O157:H7 (B). Data are expressed as mean ± SD (n = 3). Values in the same column with different superscripts are significantly different according to Duncan’s Multiple Range Test (P < 0.05).

FIGURE 5

Scanning electron microscopic (SEM) analysis of E. coli 0157:H7 and S. aureus KCTC-1621 cells treated with jineol at minimum inhibitory concentration (MIC). Controls (A,C) showing a regular and smooth surface; whereas treated cells (B,D) arrows showing disruption and cell lysis, respectively.