Photodynamic Antimicrobial Chemotherapy

Phoenix, David A.; Dennison, Sarah Rachel; Harris, Frederick

doi:10.1002/9783527676132.ch10

Cited by 21 publications

(7 citation statements)

References 325 publications

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“…[ 28 – 30 ]. In response, there have been concerted attempts to identify new antibiotics with novel mechanisms of action [ 31 – 33 ] and an attractive proposition is the development of antimicrobial peptides (AMPs), which are endogenous defence molecules produced by organisms across the eukaryotic kingdom [ 30 , 34 ]. AMPs with pH dependent activity and acid optima have been identified in wide variety of creatures ranging from cattle and rodents to mollusks and nematodes, and a number of these peptides have been developed for medical and biotechnical uses [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Linearized esculentin-2EM shows pH dependent antibacterial activity with an alkaline optimum

et al. 2021

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Here the hypothesis that linearized esculentin 2EM (E2EM-lin) from Glandirana emeljanovi possesses pH dependent activity is investigated. The peptide showed weak activity against Gram-negative bacteria (MLCs ≥ 75.0 μM) but potent efficacy towards Gram-positive bacteria (MLCs ≤ 6.25 μM). E2EM-lin adopted an α-helical structure in the presence of bacterial membranes that increased as pH was increased from 6 to 8 (↑ 15.5–26.9%), whilst similar increases in pH enhanced the ability of the peptide to penetrate (↑ 2.3–5.1 mN m−1) and lyse (↑ 15.1–32.5%) these membranes. Theoretical analysis predicted that this membranolytic mechanism involved a tilted segment, that increased along the α-helical long axis of E2EM-lin (1–23) in the N → C direction, with − < µH > increasing overall from circa − 0.8 to − 0.3. In combination, these data showed that E2EM-lin killed bacteria via novel mechanisms that were enhanced by alkaline conditions and involved the formation of tilted and membranolytic, α-helical structure. The preference of E2EM-lin for Gram-positive bacteria over Gram-negative organisms was primarily driven by the superior ability of phosphatidylglycerol to induce α-helical structure in the peptide as compared to phosphatidylethanolamine. These data were used to generate a novel pore-forming model for the membranolytic activity of E2EM-lin, which would appear to be the first, major reported instance of pH dependent AMPs with alkaline optima using tilted structure to drive a pore-forming process. It is proposed that E2EM-lin has the potential for development to serve purposes ranging from therapeutic usage, such as chronic wound disinfection, to food preservation by killing food spoilage organisms.

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Section: Introductionmentioning

confidence: 99%

Linearized esculentin-2EM shows pH dependent antibacterial activity with an alkaline optimum

et al. 2021

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“…The mechanism of antimicrobial action of AgNPs is complex and depends on both nanoparticles and silver ions released from their surface, and involves an interaction with many cellular components ( Dakal et al, 2016 ). Many natural compounds of plant origin also possess antimicrobial activity and have a potential to fight antibiotic-resistant pathogens ( Phoenix et al, 2014 ). In our previous study we demonstrated synergistic activity of an extract from Drosera binata when combined with AgNPs toward S. aureus ( Krychowiak et al, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

Silver Nanoparticles Combined With Naphthoquinones as an Effective Synergistic Strategy Against Staphylococcus aureus

et al. 2018

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Staphylococcus aureus is a human pathogen responsible for many antibiotic-resistant infections, for instance burn wound infections, which pose a threat to human life. Exploring possible synergy between various antimicrobial agents, like nanoparticles and plant natural products, may provide new weapons to combat antibiotic resistant pathogens. The objective of this study was to examine the potential of silver nanoparticles (AgNPs) to enhance the antimicrobial activity of selected naphthoquinones (NQs): plumbagin (PL), ramentaceone (RAM), droserone (DR), and 3-chloroplumbagin (3ChPL). We also attempted to elucidate the mechanism by which the AgNPs enhance the antimicrobial activity of NQs. We analyzed the interaction of AgNPs with bacterial membrane and its effect on membrane stability (TEM analysis, staining with SYTO9 and propidium iodide), as well as aggregation of NQs on the surface of nanoparticles (UV-Vis spectroscopy and DLS analysis). Our results demonstrated clearly a synergistic activity of AgNPs and three out of four tested NQs (FBC indexes ≤ 0.375). This resulted in an increase in their combined bactericidal effect toward the S. aureus reference strain and the clinical isolates, which varied in resistance profiles. The synergistic effect (FBC index = 0.375) resulting from combining 3ChPL with silver nitrate used as a control, emphasized the role of the ionic form of silver released from nanoparticles in their bactericidal activity in combination with NQs. The role of membrane damage and AgNPs-NQ interactions in the observed synergy of silver nanoparticles and NQs was also confirmed. Moreover, the described approach, based on the synergistic interaction between the above mentioned agents enables a reduction of their effective doses, thus significantly reducing cytotoxic effect of NQs toward eukaryotic HaCaT cells. Therefore, the present study on the use of a combination of agents (AgNPs-NQs) suggests its potential use as a possible strategy to combat antibiotic-resistant S. aureus.

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“…[53] In gram-negative bacteria, however, the cell wall consists of an inner and an outer membrane which envelops the peptidoglycan layer, creating an effective permeability barrier between the microorganism and its environment which tends to restrict the penetration of many photosensitizer molecules. [53,54] PACT has been demonstrated to be effective against gram-negative and gram-positive bacteria, yeasts, fungi, protozoa, and viruses, and is advantageous over antibiotics because its use does not lead to the formation of resistant bacterial strains. [55] The development of novel photosensitizer dyes with improved photo-bacterial activities remains an important research goal.…”

Section: Pact Studies Of Escherichia Coli and Staphylococcus Aureus Imentioning

confidence: 99%

2,6-Dibrominated 3,5-DistyrylBODIPYs as Photosensitizer Dyes for Photodynamic Antimicrobial Chemotherapy

Kelechi¹,

Bokolombe²,

John³

et al. 2019

MHC

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A 2,6-dibrominated BODIPY core dye with a meso-pyrenyl group has been investigated for use as a photosensitizer dye in photodynamic antimicrobial chemotherapy in the context of both gram-positive (Staphylococcus aureus) and gramnegative (Escherichia coli) bacteria, along with a π-extended 3,5-di-4-carboxystyrylBODIPY dye. The dyes are found to be effective for the treatment of S. aureus, but not in the case of E. coli.

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Photodynamic Antimicrobial Chemotherapy

Cited by 21 publications

References 325 publications

Linearized esculentin-2EM shows pH dependent antibacterial activity with an alkaline optimum

Linearized esculentin-2EM shows pH dependent antibacterial activity with an alkaline optimum

Silver Nanoparticles Combined With Naphthoquinones as an Effective Synergistic Strategy Against Staphylococcus aureus

2,6-Dibrominated 3,5-DistyrylBODIPYs as Photosensitizer Dyes for Photodynamic Antimicrobial Chemotherapy

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