Effects of free radicals from doxycycline hyclate and minocycline hydrochloride under blue light irradiation on the deactivation of Staphylococcus aureus, including a methicillin-resistant strain

Jeu-Ming P Yuann; Shwu-Yuan Lee; Sin He; Tak-Wah Wong; Meei-Ju Yang; Chien-Wei Cheng; Shiuh-Tsuen Huang; Ji-Yuan Liang

doi:10.1016/j.jphotobiol.2021.112370

Effects of free radicals from doxycycline hyclate and minocycline hydrochloride under blue light irradiation on the deactivation of Staphylococcus aureus, including a methicillin-resistant strain

J Photochem Photobiol B. 2022 Jan:226:112370. doi: 10.1016/j.jphotobiol.2021.112370. Epub 2021 Nov 27.

Authors

Jeu-Ming P Yuann¹, Shwu-Yuan Lee², Sin He¹, Tak-Wah Wong³, Meei-Ju Yang⁴, Chien-Wei Cheng¹, Shiuh-Tsuen Huang⁵, Ji-Yuan Liang⁶

Affiliations

¹ Department of Biotechnology, Ming Chuan University, Gui Shan 333321, Taiwan.
² Department of Tourism and Leisure, Hsing Wu University, New Taipei City 244012, Taiwan.
³ Department of Dermatology, National Cheng Kung University Hospital, Department of Biochemistry and Molecular Biology, College of Medicine, Center of Applied Nanomedicine, National Cheng Kung University, Tainan 70101, Taiwan.
⁴ Tea Research and Extension Station, Yangmei 326011, Taiwan.
⁵ Department of Science Education and Application, National Taichung University of Education, Taichung 40306, Taiwan; Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung 40200, Taiwan. Electronic address: hstsuen@mail.ntcu.edu.tw.
⁶ Department of Biotechnology, Ming Chuan University, Gui Shan 333321, Taiwan. Electronic address: liang121@mail.mcu.edu.tw.

PMID: 34864528
DOI: 10.1016/j.jphotobiol.2021.112370

Abstract

Doxycycline hyclate (DCH) and minocycline hydrochloride (MH) are tetracycline antibiotics and broad-spectrum antimicrobial agents. The changes in DCH and MH under blue light (λ = 462 nm) irradiation in alkaline conditions (BLIA) were investigated. Deactivation caused by superoxide anion radical (O₂^•-) and deactivation from DCH and MH during photolysis on Staphylococcus aureus (S. aureus), including methicillin-resistant S. aureus (MRSA), were studied. DCH is relatively unstable compared to MH under BLIA. The level of O₂^•- generated from the MH-treated photoreaction is lower than that from DCH photolysis, and the DCH-treated photoreaction is more efficient at inactivating S. aureus and MRSA at the same radiant intensity. DCH subjected to BLIA decreased the viability of S. aureus and MRSA by 3.84 and 5.15 log, respectively. Two photolytic products of DCH (PPDs) were generated under BLIA. The mass spectra of the PPDs featured molecular ions at m/z 460.8 and 458.8. The molecular formulas of the PPDs were C₂₁H₂₂N₂O₁₀ and C₂₂H₂₄N₂O₉, and their exact masses were 462.44 and 460.44 g/mol, respectively. These results bolster the photolytic oxidation that leads to DCH-enhanced deactivation of S. aureus and MRSA. Photochemical treatment of DCH could be applied as a supplement in hygienic processes.

Keywords: Blue light; Doxycycline; MRSA; Minocycline; Staphylococcus aureus.

MeSH terms

Staphylococcus aureus*