Investigation of the in vitro Antibacterial Efficacy of TetraF2W-RR Conjugated Chlorine e6 on MRSA

Currently, one of the most serious health problem in medicine is considered as bacterial infections. Although, antibiotics are utilized conventionally for the treatment of bacterial infections, bacteria have resistance mechanism against all currently used antibiotics. Especially, methicillin-resistant S. aureus (MRSA) is regarded as a serious clinical threat as it causes high morbidity and mortality by resisting antibiotics. Hence, the treatment of infections becomes more challenging and there is a tremendous need for the new antimicrobials that do not cause bacterial resistance. Antimicrobial peptides (AMPs) with different action mechanism that do not cause resistance and strong antimicrobial activity are considered as a promising alternative for the treatment of infections originated by multi-drug resistant bacteria. TetraF2W-RR (WWWLRRIW) is a Tryptophan-rich antimicrobial peptide with a known strong antimicrobial activity due to its WWW triple motif. Recent evidence suggests that TetraF2W-RR might be a potent antimicrobial agent for the management of infections. Although AMPs are potent antimicrobials, they can cause undesired toxic effect on host cells at high concentrations. Hence, combining AMPs with different antimicrobial strategies to create synergistic effect is becoming important to overcome toxicity. Recently, antimicrobial photodynamic therapy (aPDT) which can deactivate bacteria by providing instant photoinactivation without resistance drawn attention for the treatment of infections. Chlorin e6 (Ce6), a second generation photosensitizer approved by the FDA, is frequently used in aPDT and its strong bactericidal effect in the presence of 655 nm laser light on MRSA was reported. Herein, we have developed a novel antimicrobial that has the potential to show synergistic effect with PDT application by conjugating Ce6 and TetraF2W-RR and demonstrated the antimicrobial effect and produced ROS of Ce6-AMP conjugates.