General Information of This Peptide-drug Conjugate (PDC)
PDC ID
PDC_00300
PDC Name
PDIP-PEG1-PQ
PDC Status
Investigative
Indication
In total 1 Indication(s)
Malaria
Structure
Peptide Name
PDIP
 Peptide Info 
Receptor Name
Phosphatidylserine lipid headgroups
 Receptor Info 
Drug Name
Primaquine
 Drug Info 
Therapeutic Target
Plasmodium Deoxyribonucleic acid (Malaria DNA)
 Target Info 
Linker Name
PEG-Triazole
 Linker Info 
Peptide Modified Type
Cyclization modification
Modified Segment
Side-chain and side-chain cyclization
Formula
C193H318N50O48S2
#Ro5 Violations (Lipinski): 5 Molecular Weight 4171.103
Lipid-water partition coefficient (xlogp) -7.5767
Hydrogen Bond Donor Count (hbonddonor) 51
Hydrogen Bond Acceptor Count (hbondacc) 61
Rotatable Bond Count (rotbonds) 96
Full List of Activity Data of This Peptide-drug Conjugate
Obtained from the Model Organism Data
Click To Hide/Show 1 Activity Data Related to This Level
Experiment 1 Reporting the Activity Data of This PDC [1]
Indication Malaria
Efficacy Data Half Maximal Inhibitory Concentration (IC50)
11.3 µM
Administration Time 18-24 h
Evaluation Method Flow cytometry assay
MOA of PDC
As a proof of concept, we aimed to produce first-generation PDCs by conjugating the antimalarial drug primaquine (PQ) onto PDIP. Although PQ is one of the few drugs without clinically relevant resistance, it does not have widespread use because it causes hemolysis in individuals who are deficient in glucose-6-phosphate dehydrogenase (G6PD), a genetic trait common in malaria-endemic areas. Furthermore, PQ is metabolized into carboxyprimaquine in the body, which does not have any activity against the parasite. The proposed PDC approach provides the potential to deliver PQ directly to the parasite, which could prevent its interaction with healthy tissues and slow the conversion of PQ into inactive byproducts. Further, the combination of the peptide and drug, each with distinct antiplasmodial mechanisms of action, provides the potential to avoid the formation of drug-resistant parasites. Herein, we report the design, synthesis, and biological evaluation of a library of PDIP-PQ conjugates. Various design elements of the PDCs were probed to investigate their effect on biological activity, including: (i) the location of the PDIP conjugation site, (ii) the hydrophilicity of the linker between the peptide and drug, (iii) the spacing between the peptide and drug, and (iv) whether the linker can be cleaved to release the drug cargo under conditions which mimic the intracellular environment of infected RBCs. This work demonstrates that conjugation within the flexible interhelix spacer of PDIP and incorporation of traceless cleavable linkersbearing either a disulfide or trioxolane moietyare important for maintaining the low micromolar potency of the PQ drug cargo against P. falciparum.

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Description
The six PDIP-PQ conjugates were analyzed for their ability to inhibit the in vitro growth of P. falciparum asexual blood stage parasites (strain 3D7) in RBCs and were compared to the activity of the parent drug and peptide. We were encouraged to discover that most of the PDIP-PQ PDCs retained antiplasmodial activity similar to PDIP, with IC50 values in the low micromolar range. Notably, the various design elements probed provided valuable information regarding which PDC characteristics can be modified to improve activity.

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In Vivo Model Plasmodium falciparum 3D7.
References
Ref 1 Development of Antiplasmodial Peptide-Drug Conjugates Using a Human Protein-Derived Cell-Penetrating Peptide with Selectivity for Infected Cells. Bioconjug Chem. 2023 Jun 21;34(6):1105-1113. doi: 10.1021/acs.bioconjchem.3c00147. Epub 2023 May 26.