Premium
Synergistic Photobactericidal Activity Based on Ultraviolet‐ A Irradiation and Ferulic Acid Derivatives
Author(s) -
Shirai Akihiro,
Kajiura Masato,
Omasa Takeshi
Publication year - 2015
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12507
Subject(s) - chemistry , ferulic acid , ultraviolet , reactive oxygen species , moiety , radical , cationic polymerization , escherichia coli , flow cytometry , derivative (finance) , irradiation , photochemistry , antioxidant , nuclear chemistry , stereochemistry , biochemistry , organic chemistry , physics , genetics , quantum mechanics , biology , nuclear physics , financial economics , economics , gene
Ultraviolet‐ A ( UV ‐ A )‐mediated bactericidal activity was enhanced by combined treatment with trans ‐ferulic acid ( trans ‐ FA , compound 1 ) or its derivatives. Derivative compounds 4 and 10 contain a phenyl group or an l ‐tyrosine HC l tert ‐butyl ester, respectively, linked to the carboxyl group of trans ‐ FA . Of the three compounds, 10 exhibited the highest synergistic activity in a photobactericidal assay based on treating Escherichia coli with a derivative compound and UV ‐ A irradiation (wavelength 350–385 nm). Inactivation of viable cells at a 4.9 J cm −2 UV ‐ A fluence increased from 1.90 to 5.19 logs in the presence of 10 (100 μ m ); a 4.95‐log inactivation was achieved with 10 (5 μ m ) and a 7.4 J cm −2 UV ‐ A fluence. Addition of antioxidants significantly suppressed photosynergistic bactericidal activity, suggesting that reactive oxygen species ( ROS ) are involved in the combined bactericidal mechanism. Flow cytometry revealed that combined treatment with UV ‐ A and compound 10 , which showed the highest photobactericidal activity, generates an excess of oxidative radicals in bacterial cells. The bactericidal activity of compound 10 may be due to electrostatic interaction between the molecule's cationic moiety and the cell surface, followed by amplification of ROS generation in the cells.