Pyrazole Thioamide Prodrugs Activated by Copper or Zinc
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Solution Overview
Problem
Antibiotic resistance in bacteria has become a significant health concern, with current antibiotics requiring higher dosages and developing resistance mechanisms, necessitating the need for new drug candidates that can effectively inhibit microbial infections without triggering resistance.
Innovation Solution
Development of heterocyclic compounds with a pyrazole thioamide-based NNSN structural motif that are activated by copper or zinc, forming iminium cations to target multiple bacterial sites, thereby inhibiting microbial infections at micromolar or nanomolar concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional antibiotics are used to treat bacterial infections, then therapeutic effect is achieved, but bacteria develop resistance mechanisms and higher dosages are required
Solution Approach 1:
The compound is divided into two functional parts: a prodrug molecule that is inactive on its own, and a metal ion (copper or zinc) that activates it. The prodrug contains a thioamide group that chelates the metal ion, and only when the metal ion is bound does the compound become toxic to bacteria. This segmentation allows the compound to remain inert during distribution but become highly active at the infection site where metal ions are abundant.
Solution Approach 2:
The metal ion (copper or zinc) serves as an intermediary that bridges the prodrug and the bacterial target. The metal ion is naturally abundant at infection sites due to immune cell release, and it activates the prodrug by binding to the thioamide group, forming a complex that can then interact with bacterial Fe-S clusters and enzymes. This intermediary mechanism allows selective activation only where needed.
2Reliability
If higher dosages of antibiotics are administered to overcome resistance, then therapeutic effect is enhanced, but systemic toxicity and off-target effects increase
Solution Approach 1:
The compound exhibits different properties in different locations: it is inert and non-toxic in the bloodstream and healthy tissues, but becomes highly active and toxic only at the infection site where metal ions are concentrated. This local quality differentiation is achieved through the metal ion-dependent activation mechanism, allowing high efficacy at the target site while minimizing systemic toxicity.
Solution Approach 2:
The compound's reactivity parameter changes dramatically based on the presence of metal ions. In the absence of metal ions, the prodrug is stable and inactive. When metal ions are present (as at infection sites), the compound undergoes a parameter change to become highly reactive and toxic to bacteria. This parameter change allows selective activation without increasing systemic dosage.
3Ease of manufacture
If single-target antibiotics are used, then specific bacterial pathways are inhibited, but resistance development is facilitated
Solution Approach 1:
The activated compound performs multiple functions simultaneously: it generates reactive oxygen species, chelates metal ions, disrupts Fe-S clusters, and interferes with enzyme function. This multi-functionality means the compound attacks multiple bacterial targets at once, making it much harder for bacteria to develop resistance compared to single-target antibiotics. The universal applicability to multiple bacterial systems enhances efficacy while reducing resistance risk.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These compounds achieve targeted and localized treatment, reducing the likelihood of resistance development and systemic toxicity, with lower therapeutic concentrations required, and demonstrate broad-spectrum activity against various bacteria and fungi.
Implementation Method 1
These compounds upon administration react with endogenous Cu2+ or Zn2+ that has accumulated at sites of infection. Copper(I)-activation of the compounds leads to the formation of an iminium-type cation.
Implementation Method 2
Copper I/II facilitates Fenton-type biochemistry at the low pH in phagolysosomes (phagosomes after fusing with lysosomes), which is able to damage the bacterial membranes
Implementation Method 3
Inside bacteria, copper I/II is capable of destroying Fe—S clusters, inactivating various essential bacterial enzymes using Fe—S clusters as cofactors.
Implementation Method 4
Similarly, there is evidence that zinc exerts an antimicrobial effect by antagonizing the uptake of other key trace metal nutrients.
Data Source
AI summary
Heterocyclic compounds with a novel pyrazole thioamide-based NNSN structural motif, having highly effective zinc- or copper-activated toxicity against microbial infections at micromolar or nanomolar minimum inhibitory concentrations (MIC), and methods of making and using the same.