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Updated: Jun 21, 2026

Anti-virulent Disruption of Pathogenic Biofilms using Engineered Quorum-quenching Lactonases
Published on: January 1, 2016
A quinol peroxidase inhibitor prevents secretion of a leukotoxin from Aggregatibacter actinomycetemcomitans
E Takashima1, H Yamada, A Yajima
1Department of Microbiology, School of Life Dentistry at Tokyo, The Nippon Dental University, Chiyoda-ku, Tokyo, Japan. eizo.takashima@gmail.com
Background And Objective:
Quinol peroxidase (QPO) catalyzes peroxidase activity using quinol in the respiratory chain as a substrate. Quinol peroxidase is essential for the secretion of leukotoxin (LtxA), which destroys leukocytes and erythrocytes in humans and is one of the major virulence factors of Aggregatibacter actinomycetemcomitans, which is associated with localized aggressive periodontitis. In the present study, we aimed to find a highly potent QPO inhibitor to attenuate the virulence of A. actinomycetemcomitans.
Material And Methods:
For screening of QPO inhibitors, QPO activity was measured kinetically by SpectraMax Plus with 96-well UV plates. Three hundred compounds in the Kitasato Institute for Life Sciences Chemical Library were screened. Secretion of LtxA in the culture supernatant was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cytotoxicity against human promyelocytic leukemia cell line (HL-60) cells from the culture supernatant was measured by Trypan Blue exclusion test.
Results:
The present study characterized ascofuranone as a highly potent inhibitor of QPO (K(i) = 9.557 +/- 0.865 nm). Ascofuranone inhibited secretion of LtxA by A. actinomycetemcomitans in a dose-dependent manner, making A. actinomycetemcomitans less pathogenic to HL-60 cells.
Conclusion:
Quinol peroxidase inhibitors are promising candidates as alternative drugs for the treatment and prevention of the onset of localized aggressive periodontitis. Using ascofuranone as a seed compound, further study of QPO inhibitors could provide novel chemotherapeutic strategies for controlling localized aggressive periodontitis.
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