Effect of photodynamic inactivation of Escherichia coli by hypericin

Abstract

The present study has focused on the effects of hypericin (Hyp) based photodynamic inactivation (PDI) of Escherichia coli (E. coli). To evaluate the efficiency of Hyp based PDI of E. coli, single factor experiments and response surface optimization experiment were conducted to obtain the optimum parameter values (36 µM Hyp, 5.9 J cm light dose: 16.4 mW cm, 60 W, 260 s, 590 nm and 68 min incubation time) and finally achieved a 4.1 log CFU mL decrease of E. coli. Cell-Hyp interaction and intracellular reactive oxygen species (ROS) level were detected by fluorescence spectrometric photometer. Data indicated that Hyp possessed a strong ability to bind with cells. In addition, a significant increase was observed in intracellular ROS level after Hyp-based photosensitization treatment. Therefore, Hyp-based photosensitization seems to be a promising method to efficiently inactivate E. coli. It is expected to be a safe, efficient, low cost and practical method which can be applied in the field of food safety.

Distinguishing Activities in the Photodynamic Arsenals of the Pigmented Ciliates Blepharisma sinuosum Sawaya, 1940 and Blepharisma japonicum Suzuki, 1954 (Ciliophora: Heterotrichea)

“…Minor but significant variations on specific points along the E. coli curves were detected, mostly in the treatments with higher concentration of pigments, but these were not registered as conclusive observations. This is in agreement with previous results for B. japonicum pigments (19) and with the hypothesis that Gram‐negative bacteria are generally refractory to photodynamic therapy (PDT) (57), including to hypericin treatments (58). Such resistance has been associated with the cell envelope of Gram‐negative bacteria that act as a barrier impairing the uptake of photosensitizers (59).…”

Antimicrobial Photoinactivation Approach Based on Natural Agents for Control of Bacteria Biofilms in Spacecraft

“…It is known that Hyp is a neutral hydrophobic PS. Therefore, it does not simply get into Gram-negative bacteria such as E. coli [106,108,110,114,115], P. aeruginosa [100,106], and Salmonella enterica [112]. De Melo et al (2013) used electroporation to increase the uptake of Hyp, thus enhancing the inactivation of E. coli to 3.5 logs [108].…”

“…Furthermore, the required illumination doses have to be discussed and compared with general illumination conditions. RF can be excited by blue light and requires from 3 to 400 J/cm 2 according to the data available in the literature (see Table S1 of Supplementary Material ) [ 93 , 94 , 95 , 96 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 117 , 118 , 119 , 120 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 148 , 149 , 150 , 153 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 165 , 173 , 175 , 176 , 177 , 178 , 179 , 180 , 181 ,…”

Effect of Photoactivated Hypericin on Growth and Antibiotic Susceptibility of Hospital-Related <i>Staphylococcus aureus</i> and <i>Enterococcus sp.</i> Clinical Strains

“…Because the diffusion of 1 O 2 is not longer than 0.3 μm (depending on surrounding environment), an oxidative damage takes place in close vicinity to the on light dependent anti-tumor [13] [14] and anti-viral activity [14]. Several articles reported an application of Hyp in inactivation of Gram+ and Gram− microorganisms in the field of food safety [15]. Its photoactivity is characterized by high ROS generation, predominantly 1 O 2 production through the type II mechanism of the photodynamic action [9] [14] (Figure 1(a)).…”