Photo-irradiated caffeic acid exhibits antimicrobial activity against Streptococcus mutans biofilms via hydroxyl radical formation

Abstract

An antimicrobial technique based on photo-oxidation of caffeic acid (CA) has recently been developed, but its effect on biofilm-forming bacteria is unknown. The present study aimed to evaluate the effect of photo-irradiated CA against Streptococcus mutans (cariogenic bacteria) biofilm as it relates to hydroxyl radical formation. S. mutans biofilms grown on hydroxyapatite disks were immersed in CA solution (0–2 mg/mL) and irradiated with LED light at wavelengths of 365, 385, and 400 nm and at irradiances of 500, 1000, and 2000 mW/cm2 for 4 min. Biofilm viable bacterial counts were determined by colony counting. The yield of hydroxyl radicals generated by the LED irradiation of CA solution was quantified by electron spin resonance analysis. Of the conditions tested, the highest bactericidal effect, with a > 5-log reduction in viable bacterial counts, was obtained by irradiation of a 1 mg/mL CA solution with 385 nm LED and at an irradiance of 2000 mW/cm2. Hydroxyl radical formation was related to this bactericidal effect. The present study suggests that the antimicrobial technique based on the 385 nm LED irradiation of CA is effective against cariogenic biofilms and can be applied as an adjunctive chemotherapy for dental caries.

Antioxidant or pro-oxidant and glutathione transferase P1-1 inhibiting activities for Tamarindus indica seeds and their cytotoxic effect on MCF-7 cancer cell line

“…Plants contain a number of chemicals, including phenolic acids, which have been identified as potential internal biological activity, and methods of extraction are commonly used for their recovery. Growing plant produces and accumulates a certain amount of these compounds in its tissues, and their attractiveness to solvents varies by polarity [ 34 ]. The first step in the use of phytochemicals is the extraction of bioactive compounds from plant materials.…”

Antimicrobial Blue Light versus Pathogenic Bacteria: Mechanism, Application in the Food Industry, Hurdle Technologies and Potential Resistance

“…Similarly, inactivation of S. mutans within biofilms was reported after exposure to the combination of caffeic acid (0–2 mg/mL) and light (365, 385 and 400 nm; 120–480 J/cm 2 ), with the highest inactivation (5 log CFU/mL) achieved at caffeic concentration of 2 mg/mL and blue light dosage of 480 J/cm 2 (385 nm) [ 231 ]. Other authors also reported the synergistic antimicrobial activities of blue light (400 nm) and wine grape-derived polyphenols (for example, catechin and its isotopic ingredients) against S. aureus or P. aeruginosa (5 log CFU/mL) [ 232 , 233 ].…”

Antimicrobial Intervention by Photoirradiation of Grape Pomace Extracts via Hydroxyl Radical Generation

“…A recent study demonstrated that antimicrobial technique based on photooxidation of caffeic acid was highly effective against biofilm-forming Streptococcus mutans , the most common acidogenic bacterial species isolated from human cariogenic dental plaques, in relation to ·OH formation (Nakamura et al, 2017 ). Therefore, the authors concluded that photoirradiation of caffeic acid has the potential to be applied as an inexpensive antimicrobial therapy to prevent and treat dental caries.…”