Photodynamic Effects of Antioxidant Substituted Porphyrin Photosensitizers on Gram-positive and -negative Bacteria¶

Abstract

Photodynamic treatment of the gram‐negative bacteria Escherichia coli B and Acinetobacter baumannii and the gram‐positive bacterium Staphylococcus aureus was performed using two newly devised and synthesized antioxidant carrier photosensitizers (antioxidant carrier sensitizers‐2 [ACS‐2] and antioxidant carrier sensitizers‐3 [ACS‐3]), which are butyl hydroxy toluene and propyl gallate substituted haematoporphyrins, respectively. It was found that ACS‐2 is less reactive than other photosensitizers previously used for the same purpose, whereas ACS‐3 is very effective against the multidrug‐resistant bacterium A. baumannii, causing its complete eradication at a low fluence (∼7.5 J/cm) of blue light (407–420 nm) and a low concentration (10 μM). At a higher fluence (∼37.5 J/cm) complete eradication of E. coli B can be obtained under the same conditions. Furthermore, X‐ray microanalysis and ultrastructural changes indicate that ACS‐3, especially in the case of photodynamic treatment of A. baumannii, interferes with membrane functions and causes the inactivation of the bacterium. ACS‐3 may be suggested as a specific photosensitization agent for photoinactivation of gram‐negative bacteria.

Photoinactivation of Hepatitis A Virus by Synthetic Porphyrins¶

“…Quantum yields of 1 O 2 for the porphyrins used in this study were assumed to be within this less than two‐fold range, which is insufficient to account for the differences in potency observed for the different porphyrins. Although there are no published studies on the photosensitization of HAV and MS2 by meso ‐substituted porphyrins, the results presented in this study are consistent with earlier studies suggesting that some porphyrins and porphyrin derivatives are effective agents for the inactivation of viruses (9,10,35–37) and bacteria (13,14,17,18,38). Porphyrins also are reported to inhibit the conversion of protease‐sensitive proteins to protease‐resistant (prion) forms (39,40).…”

“…Subsequent development of porphyrins for therapeutic uses has favored a nonphysiological substituent pattern in which the meso carbons [C5,C10,C15,C20] bear aryl or alkyl substituents, for example dihydro tetrakis( m ‐hydroxyphenyl)porphyrin Temoporphin TM (11) because of more convenient synthetic routes leading to single compounds in high purity. To date, there are a few reports of such second‐generation porphyrins for bacterial inactivation (12–18) but none for viral inactivation.…”

Sensitivity of Staphylococcus aureus Strains to Broadband Visible Light

“…An alternative approach for killing topical bacteria is by lethal photosensitization (photodynamic therapy—PDT) which was suggested some years ago (6–8). In PDT, reactive oxygen species (ROS), mainly singlet oxygen, generated by the illuminated photosensitizer that was introduced into the bacteria were found to cause the lethal effect (9–11).…”

Enhanced inactivation of bacteria by metal‐oxide nanoparticles combined with visible light irradiation

“…Since the effectiveness of antibiotic treatment is decreasing, due to the development of resistant strains 17, an alternative approach for killing bacteria present in topical wounds is by lethal photosensitization through the use of photodynamic therapy (PDT), which was suggested some years ago 18–20. In PDT, ROS generated by an illuminated photosensitizer introduced exogenously into the bacteria induce a toxic effect 21–23.…”