Photodynamic antimicrobial activity of magnesium(II) porphyrazine with bulky peripheral sulfanyl substituents

Abstract

Magnesium(II) porphyrazine bearing bulky sulfanyl substituents was evaluated as a photosensitizer (PS) for photodynamic antimicrobial chemotherapy (PACT). In the photostability study, the studied porphyrazine under light irradiation decomposed via photobleaching process with quantum yields up to 1.05 ⋅ 10⁻⁵. Singlet oxygen quantum yields for the PS were determined by indirect method with chemical singlet oxygen trap (1,3-diphenylisobenzofuran, DPBF) and reference (unsubstituted zinc(II) phthalocyanine). Liposomes containing porphyrazine derivative were obtained with thin-film hydration method and their size was measured with NanoSight LM10 (Malvern). Biological activity evaluation was performed with the agar plate method. The photocytotoxicity of sulfanyl porphyrazine against various wound bacteria (Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, and Streptococcus pyogenes) was studied. The highest reduction value in bacterial growth exceeding 4 log was observed for S. epidermidis. Equally high reduction values of 3.4 log and 4.2 log at 10 and 100 µM, respectively, were observed against S. pyogenes. The novel sulfanyl porphyrazine can be considered as a potential PS in further antimicrobial photodynamic therapy related studies.

Graphical Abstract

Keywords:

• Sulfanyl porphyrazines
• singlet oxygen
• photodynamic therapy (PDT)
• PACT
• photobleaching

Disclosure statement

There is no conflict of interest disclosed by the authors.

Additional information

Funding

This research was funded by the National Science Centre, Poland, grant number 2016/21/B/NZ9/00783.