Advancing sepsis treatment: synthesis and evaluation of multi-target drugs with antimicrobial, antioxidant and anticoagulant properties.

West, Jordan Emma

Abstract

Sepsis is a complex disease that affects individuals of all ages but is particularly dangerous for vulnerable populations, such as newborns, the elderly and those with weakened immune systems. It is triggered by infection, leading to hyperinflammation, oxidative stress (OS), excessive blood coagulation and, in severe cases, death. Globally, sepsis accounts for approximately 11 million deaths each year, with around 245,000 cases reported annually in the UK. The intricate clinical nature of sepsis renders single-target therapies, such as antibiotics, fluid resuscitation and vasopressors, ineffective in many cases. This project aims to develop a series of multi-target drugs (MTDs) to address the various pathologies of sepsis, specifically targeting infection, OS, and abnormal blood coagulation. A total of 11 MTD (JW1-JW11) compounds were synthesised, incorporating Naphthalimido and phenolic groups, with yields ranging from 23% to 92%. These compounds were fully characterised using high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR; 1H and 13C). Their antimicrobial properties were evaluated through standard 96-well plate microdilution to determine the minimum inhibitory concentration (MIC) and time-kill kinetics assays to assess bacterial survival over time against Escherichia coli and Staphylococcus aureus. Compounds JW6 and JW10 exhibited the lowest MIC among the synthesised compounds, measuring 125 μg/mL against E. coli and 250 μg/mL against S. aureus. Time-kill kinetics assays confirmed that JW6 and JW10 contain bactericidal properties, as no bacterial growth was observed after 24 hours at a dosage of twice the MIC. Antioxidant activity was investigated using Ferric Reducing Antioxidant Power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, with all compounds showing antioxidant activity. JW6, JW7 and JW10 demonstrated strong activity in the DPPH assay, with lead compounds JW6 and JW10 exhibiting IC50 values of 40.70 μM and 38.90 μM, respectively. In the FRAP assay, JW10 exhibited 1.25 Trolox equivalent (TE). The clot lysis assay was performed to investigate the anticoagulant properties. Compounds JW1, JW4, JW9 and JW11 demonstrated the strongest fibrinolytic activity, achieving a 50% clot lysis time of 68-78 minutes compared to the control (Pooled Normal Plasma + Phospholipids + tPA), which had a 50% clot lysis time of 70 minutes (p < 0.05). Compounds JW3, JW5, JW7 and JW8 showed the lowest maximum absorbance of 0.2, indicating reduced clot density compared to the control (PNP+Pl), with an absorbance of 0.4 at 405 nm. The antibacterial and antioxidant properties of the compounds highlight their potential as MTD candidates for sepsis treatment. Further investigations into specific drug targets and mechanisms of action are required. By addressing the multifaceted nature of sepsis through simultaneous targeting of infection, OS, and blood clotting, these compounds provide ideal candidates for further optimisation, particularly JW6 and JW10. Future research will include mechanisms of action studies and in vivo testing to assess the toxicity of the compounds. This study underscores the relevance of the MTD strategy in managing complex diseases such as sepsis, where single-target therapies may be insufficient.

Citation

WEST, J.E. 2024. Advancing sepsis treatment: synthesis and evaluation of multi-target drugs with antimicrobial, antioxidant and anticoagulant properties. Robert Gordon University, MRes thesis. Hosted on OpenAIR [online]. Available from: https://doi.org/10.48526/rgu-wt-2795403

• Thesis Type: Thesis
• Deposit Date: Apr 16, 2025
• Publicly Available Date: Apr 16, 2025
• DOI: https://doi.org/10.48526/rgu-wt-2795403
• Keywords: Sepsis; Naphthalimide; Antimicrobials; Antioxidants; Anticoagulants; Multi-target strategies
• Public URL: https://rgu-repository.worktribe.com/output/2795403
• Award Date: Dec 31, 2024