Comparison and Mechanism Study of Antibacterial Activity of Cationic and Neutral Oligo-Thiophene-Ethynylene

Abstract

Photodynamic therapy (PDT) is a potential approach to resolve antibiotic resistance, and phenylene/thiophene-ethynylene oligomers have been widely studied as effective antibacterial reagents. Oligomers with thiophene moieties usually exhibit good antibacterial activity under light irradiation and dark conditions. In the previous study, we verified that neutral oligo-p-phenylene-ethynylenes (OPEs) exhibit better antibacterial activity than the corresponding cationic ones; however, whether this regular pattern also operates in other kinds of oligomers such as oligo-thiophene-ethynylene (OTE) is unknown. Also, the antibacterial activity comparison of OTEs bearing cyclic and acyclic amino groups will offer useful information to further understand the role of amino groups in the antibacterial process and guide the antibacterial reagent design as amino groups affect the antibacterial activity a lot. We synthesized four OTEs bearing neutral or cationic, cyclic, or acyclic amino groups and studied their antibacterial activity in detail. The experimental results indicated that the OTEs exhibited better antibacterial activity than the OPEs, the neutral OTEs exhibited better antibacterial activity in most cases, and OTEs bearing cyclic amino groups exhibited better antibacterial activity than those bearing acyclic ones in most cases. This study provides useful guidelines for further antibacterial reagent design and investigations.

Excited State and Reactive Oxygen Species against Cancer and Pathogens: A Review on Sonodynamic and Sono‐Photodynamic Therapy

“…When considering PDT and SDT against microbes, there are two main concerns about sensitizers: their ability to generate singlet oxygen efficiently and the ability to get in the close neighborhood of the treated pathogen's structures e. g. cell membrane. Thus, sensitizers that are bonded with targeted bacteria, for example, sensitizers bearing several positive charges, such as tetrakis(1‐methylpyridinium‐4‐yl)porphyrin tetraiodide 1 (Figure 4) together with high lipophilicity at their peripheries indicate better results despite being less efficient at generating singlet oxygen [3,26–29] . The inactivation of bacteria may be very effective, for instance, 2,3‐bis((4‐(3,5‐bis(hydroxymethyl))butyl)tio)tribenzoporphyrazine 2 (Figure 4) used against S. aureus represents the killing rate of over 5.9 log at a concentration of 10 μM and under low light doses [25] .…”

“…Thus, sensitizers that are bonded with targeted bacteria, for example, sensitizers bearing several positive charges, such as tetrakis(1-methylpyridinium-4-yl)porphyrin tetraiodide 1 (Figure 4) together with high lipophilicity at their peripheries indicate better results despite being less efficient at generating singlet oxygen. [3,[26][27][28][29] The inactivation of bacteria may be very effective, for instance, 2,3-bis((4-(3,5bis(hydroxymethyl))butyl)tio)tribenzoporphyrazine 2 (Figure 4) used against S. aureus represents the killing rate of over 5.9 log at a concentration of 10 μM and under low light doses. [25] The PDT and SDT might be combined with antibiotic therapy resulting in increased disinfection efficacy on bacterial pathogens compared to monotherapies alone.…”

TfOH-promoted multichannel transformations of trifluoromethyl side chain substituted thiophene and furan families to access antimicrobial agents

“…Since the thiophene ring is an essential part of the widely used antibiotics Cefoxitin and Temocillin, as well as antifungal agents such as Sertaconazole and Tioconazole (Fig. 1), a significant body of current research is devoted to the synthesis and investigation of antimicrobial activity of some novel thiophene derivatives, 2–9 including recently isolated natural compounds, 10 as well as thiophene-containing metal–organic complexes, 11,12 oligomeric 13,14 and polymeric materials. 15…”