General Information of This Peptide-drug Conjugate (PDC)
PDC ID
PDC_00503
PDC Name
XRRR - Nalidixic acid conjugate
PDC Status
Investigative
Indication
In total 1 Indication(s)
Staphylococcus aureus infection
Structure
Peptide Name
XRRR
 Peptide Info 
Receptor Name
DNA gyrase subunit B (gyrB)
 Receptor Info 
Drug Name
Nalidixic Acid
 Drug Info 
Linker Name
Amide bond
 Linker Info 
Formula
C30H49N15O5
#Ro5 Violations (Lipinski): 4 Molecular Weight 699.822
Lipid-water partition coefficient (xlogp) -3.56108
Hydrogen Bond Donor Count (hbonddonor) 10
Hydrogen Bond Acceptor Count (hbondacc) 10
Rotatable Bond Count (rotbonds) 20
Full List of Activity Data of This Peptide-drug Conjugate
Revealed Based on the Cell Line Data
Click To Hide/Show 5 Activity Data Related to This Level
Experiment 1 Reporting the Activity Data of This PDC [1]
Indication <i>Staphylococcus aureus</i> infection
Efficacy Data Half maximal inhibitory concentration (IC50) >  80 μM
Administration Time 24 h
MOA of PDC
Nalidixic acid (NA) is a first-generation quinolone-based antibiotic that has a narrow spectrum and poor pharmacokinetics. Here, we describe a family of peptide-nalidixic acid conjugates featuring different levels of hydrophobicity and molecular charge prepared by solid-phase peptide synthesis that exhibit intriguing improvements in potency. In comparison to NA, which has a low level of potency in S. aureus, the NA peptide conjugates with optimized hydrophobicities and molecular charges exhibited significantly improved antibacterial activity. The most potent NA conjugate-featuring a peptide containing cyclohexylalanine and arginine-exhibited efficient bacterial uptake and, notably, specific inhibition of S. aureus DNA gyrase. A systematic study of peptide-NA conjugates revealed that a fine balance of cationic charge and hydrophobicity in an appendage anchored to the core of the drug is required to overcome the intrinsic resistance of S. aureus DNA gyrase toward this quinolone-based drug.

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Description
As expected, unconjugated NA showed limited activity toward MRSA and MSSA. Peptide vectors alone did not show significant toxicity to both MRSA and MSSA at all concentrations investigated. However, several of the peptide/drug conjugates, compounds 4 and 5 in particular, exhibited much lower IC50 and MIC values in both strains of the bacteria. A comparison of the hydrophobicities and molecular charges of the peptide/drug conjugates indicates that these two properties exert significant influence over the activities of these molecules. Hydrophobicity, measured by monitoring HPLC elution profiles, increased in the following order: 2 6 < 3 &tide; 4 < 5. The peptide conjugates that exhibited the highest potencies, compounds 4 and 5, had the highest levels of hydrophobicity. Compound 3, which had a similar level of hydrophobicity relative to these compounds, exhibited a lower level of toxicity, indicating that hydrophobicity alone does not control activity. This compound also carries a lower molecular charge, pointing to this parameter as another influencer of potency.

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In Vitro Model Staphylococcus aureus infection Staphylococcus aureus 1280
Experiment 2 Reporting the Activity Data of This PDC [1]
Indication <i>Staphylococcus aureus</i> infection
Efficacy Data Half maximal inhibitory concentration (IC50) >  80 μM
Administration Time 24 h
MOA of PDC
Nalidixic acid (NA) is a first-generation quinolone-based antibiotic that has a narrow spectrum and poor pharmacokinetics. Here, we describe a family of peptide-nalidixic acid conjugates featuring different levels of hydrophobicity and molecular charge prepared by solid-phase peptide synthesis that exhibit intriguing improvements in potency. In comparison to NA, which has a low level of potency in S. aureus, the NA peptide conjugates with optimized hydrophobicities and molecular charges exhibited significantly improved antibacterial activity. The most potent NA conjugate-featuring a peptide containing cyclohexylalanine and arginine-exhibited efficient bacterial uptake and, notably, specific inhibition of S. aureus DNA gyrase. A systematic study of peptide-NA conjugates revealed that a fine balance of cationic charge and hydrophobicity in an appendage anchored to the core of the drug is required to overcome the intrinsic resistance of S. aureus DNA gyrase toward this quinolone-based drug.

   Click to Show/Hide
Description
As expected, unconjugated NA showed limited activity toward MRSA and MSSA. Peptide vectors alone did not show significant toxicity to both MRSA and MSSA at all concentrations investigated. However, several of the peptide/drug conjugates, compounds 4 and 5 in particular, exhibited much lower IC50 and MIC values in both strains of the bacteria. A comparison of the hydrophobicities and molecular charges of the peptide/drug conjugates indicates that these two properties exert significant influence over the activities of these molecules. Hydrophobicity, measured by monitoring HPLC elution profiles, increased in the following order: 2 6 < 3 &tide; 4 < 5. The peptide conjugates that exhibited the highest potencies, compounds 4 and 5, had the highest levels of hydrophobicity. Compound 3, which had a similar level of hydrophobicity relative to these compounds, exhibited a lower level of toxicity, indicating that hydrophobicity alone does not control activity. This compound also carries a lower molecular charge, pointing to this parameter as another influencer of potency.

   Click to Show/Hide
In Vitro Model Staphylococcus aureus infection Staphylococcus aureus 1280
Experiment 3 Reporting the Activity Data of This PDC [1]
Indication <i>Staphylococcus aureus</i> infection
Efficacy Data Half maximal inhibitory concentration (IC50) >  800 μM
Administration Time 2 h
MOA of PDC
Nalidixic acid (NA) is a first-generation quinolone-based antibiotic that has a narrow spectrum and poor pharmacokinetics. Here, we describe a family of peptide-nalidixic acid conjugates featuring different levels of hydrophobicity and molecular charge prepared by solid-phase peptide synthesis that exhibit intriguing improvements in potency. In comparison to NA, which has a low level of potency in S. aureus, the NA peptide conjugates with optimized hydrophobicities and molecular charges exhibited significantly improved antibacterial activity. The most potent NA conjugate-featuring a peptide containing cyclohexylalanine and arginine-exhibited efficient bacterial uptake and, notably, specific inhibition of S. aureus DNA gyrase. A systematic study of peptide-NA conjugates revealed that a fine balance of cationic charge and hydrophobicity in an appendage anchored to the core of the drug is required to overcome the intrinsic resistance of S. aureus DNA gyrase toward this quinolone-based drug.

   Click to Show/Hide
Description
As expected, unconjugated NA showed limited activity toward MRSA and MSSA. Peptide vectors alone did not show significant toxicity to both MRSA and MSSA at all concentrations investigated. However, several of the peptide/drug conjugates, compounds 4 and 5 in particular, exhibited much lower IC50 and MIC values in both strains of the bacteria. A comparison of the hydrophobicities and molecular charges of the peptide/drug conjugates indicates that these two properties exert significant influence over the activities of these molecules. Hydrophobicity, measured by monitoring HPLC elution profiles, increased in the following order: 2 6 < 3 &tide; 4 < 5. The peptide conjugates that exhibited the highest potencies, compounds 4 and 5, had the highest levels of hydrophobicity. Compound 3, which had a similar level of hydrophobicity relative to these compounds, exhibited a lower level of toxicity, indicating that hydrophobicity alone does not control activity. This compound also carries a lower molecular charge, pointing to this parameter as another influencer of potency.

   Click to Show/Hide
In Vitro Model Staphylococcus aureus infection Staphylococcus aureus infection strain 1280
Experiment 4 Reporting the Activity Data of This PDC [1]
Indication <i>Staphylococcus aureus</i> infection
Efficacy Data Minimum inhibitory concentration (MIC) . Not detected
Administration Time 24 h
MOA of PDC
Nalidixic acid (NA) is a first-generation quinolone-based antibiotic that has a narrow spectrum and poor pharmacokinetics. Here, we describe a family of peptide-nalidixic acid conjugates featuring different levels of hydrophobicity and molecular charge prepared by solid-phase peptide synthesis that exhibit intriguing improvements in potency. In comparison to NA, which has a low level of potency in S. aureus, the NA peptide conjugates with optimized hydrophobicities and molecular charges exhibited significantly improved antibacterial activity. The most potent NA conjugate-featuring a peptide containing cyclohexylalanine and arginine-exhibited efficient bacterial uptake and, notably, specific inhibition of S. aureus DNA gyrase. A systematic study of peptide-NA conjugates revealed that a fine balance of cationic charge and hydrophobicity in an appendage anchored to the core of the drug is required to overcome the intrinsic resistance of S. aureus DNA gyrase toward this quinolone-based drug.

   Click to Show/Hide
Description
As expected, unconjugated NA showed limited activity toward MRSA and MSSA. Peptide vectors alone did not show significant toxicity to both MRSA and MSSA at all concentrations investigated. However, several of the peptide/drug conjugates, compounds 4 and 5 in particular, exhibited much lower IC50 and MIC values in both strains of the bacteria. A comparison of the hydrophobicities and molecular charges of the peptide/drug conjugates indicates that these two properties exert significant influence over the activities of these molecules. Hydrophobicity, measured by monitoring HPLC elution profiles, increased in the following order: 2 6 < 3 &tide; 4 < 5. The peptide conjugates that exhibited the highest potencies, compounds 4 and 5, had the highest levels of hydrophobicity. Compound 3, which had a similar level of hydrophobicity relative to these compounds, exhibited a lower level of toxicity, indicating that hydrophobicity alone does not control activity. This compound also carries a lower molecular charge, pointing to this parameter as another influencer of potency.

   Click to Show/Hide
In Vitro Model Staphylococcus aureus infection Staphylococcus aureus 1280
Experiment 5 Reporting the Activity Data of This PDC [1]
Indication <i>Staphylococcus aureus</i> infection
Efficacy Data Minimum inhibitory concentration (MIC) . Not detected
Administration Time 24 h
MOA of PDC
Nalidixic acid (NA) is a first-generation quinolone-based antibiotic that has a narrow spectrum and poor pharmacokinetics. Here, we describe a family of peptide-nalidixic acid conjugates featuring different levels of hydrophobicity and molecular charge prepared by solid-phase peptide synthesis that exhibit intriguing improvements in potency. In comparison to NA, which has a low level of potency in S. aureus, the NA peptide conjugates with optimized hydrophobicities and molecular charges exhibited significantly improved antibacterial activity. The most potent NA conjugate-featuring a peptide containing cyclohexylalanine and arginine-exhibited efficient bacterial uptake and, notably, specific inhibition of S. aureus DNA gyrase. A systematic study of peptide-NA conjugates revealed that a fine balance of cationic charge and hydrophobicity in an appendage anchored to the core of the drug is required to overcome the intrinsic resistance of S. aureus DNA gyrase toward this quinolone-based drug.

   Click to Show/Hide
Description
As expected, unconjugated NA showed limited activity toward MRSA and MSSA. Peptide vectors alone did not show significant toxicity to both MRSA and MSSA at all concentrations investigated. However, several of the peptide/drug conjugates, compounds 4 and 5 in particular, exhibited much lower IC50 and MIC values in both strains of the bacteria. A comparison of the hydrophobicities and molecular charges of the peptide/drug conjugates indicates that these two properties exert significant influence over the activities of these molecules. Hydrophobicity, measured by monitoring HPLC elution profiles, increased in the following order: 2 6 < 3 &tide; 4 < 5. The peptide conjugates that exhibited the highest potencies, compounds 4 and 5, had the highest levels of hydrophobicity. Compound 3, which had a similar level of hydrophobicity relative to these compounds, exhibited a lower level of toxicity, indicating that hydrophobicity alone does not control activity. This compound also carries a lower molecular charge, pointing to this parameter as another influencer of potency.

   Click to Show/Hide
In Vitro Model Staphylococcus aureus infection Staphylococcus aureus 1280
References
Ref 1 Enhancing the Potency of Nalidixic Acid toward a Bacterial DNA Gyrase with Conjugated Peptides. ACS Chem Biol. 2017 Oct 20;12(10):2563-2569. doi: 10.1021/acschembio.7b00540. Epub 2017 Sep 1.