Bactericidal Activity and Mechanism of Photoirradiated Polyphenols against Gram-Positive and -Negative Bacteria

Keisuke Nakamura, Kirika Ishiyama, Hong Sheng, Hiroyo Ikai, Taro Kanno, Yoshimi Niwano

Research output: Contribution to journalArticlepeer-review

81 Citations (Scopus)


The bactericidal effect of various types of photoirradiated polyphenols against Gram-positive and -negative bacteria was evaluated in relation to the mode of action. Gram-positive bacteria (Enterococcus faecalis, Staphylococcus aureus, and Streptococcus mutans) and Gram-negative bacteria (Aggregatibacter actinomycetemcomitans, Escherichia coli, and Pseudomonas aeruginosa) suspended in a 1 mg/mL polyphenol aqueous solution (caffeic acid, gallic acid, chlorogenic acid, epigallocatechin, epigallocatechin gallate, and proanthocyanidin) were exposed to LED light (wavelength, 400 nm; irradiance, 260 mW/cm2) for 5 or 10 min. Caffeic acid and chlorogenic acid exerted the highest bactericidal activity followed by gallic acid and proanthocyanidin against both Gram-positive and -negative bacteria. It was also demonstrated that the disinfection treatment induced oxidative damage of bacterial DNA, which suggests that polyphenols are incorporated into bacterial cells. The present study suggests that blue light irradiation of polyphenols could be a novel disinfection treatment.

Original languageEnglish
Pages (from-to)7707-7713
Number of pages7
JournalJournal of Agricultural and Food Chemistry
Issue number35
Publication statusPublished - 2015 Sept 9


  • Gram-negative bacteria
  • Gram-positive bacteria
  • bactericidal effect
  • photoirradiation
  • polyphenols

ASJC Scopus subject areas

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)


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