Design of Cyclic-ADT Peptides to Improve Drug Delivery to the Brain via Inhibition of E-Cadherin Interactions at the Adherens Junction

We have developed linear cadherin peptides (i.e., HAV- and ADT peptides) that enhance brain delivery of drug molecules to the central nervous system (CNS). These peptides modulate cadherin interactions in the adherens junctions of the vascular endothelial cells in the blood-brain barrier (BBB) to increase paracellular drug permeation. In this study, the goal was to design cyclic peptides (ADTC1, ADTC5, and ADTC6) derived from linear ADT6 (Ac-ADTPPV-NH2) to improve their stability and biological activity in improving paracellular delivery of drugs into the brain. The ADTC1 peptide (cyclo(1,8)Ac-CADTPPVC-NH2) was designed by adding two Cys residues at the N- and C-terminus of ADT6 peptide and a disulfide bond from thiol groups of the Cys residues. The ADTC5 peptide (cyclo(1,7)Ac-CDTPPVC-NH2) was derived from ADTC1 by deleting the alanine residue from the N-terminal region of ADTC1 and ADTC6. (Cyclo(1,6)Ac-CDTPPC-NH2) was constructed by deleting the valine residue from the C-terminal region of ADTC5. The results showed that ADTC1 has activity in inhibiting the resealing of the intercellular junctions of the MDCK cell monolayers similar to that of the linear ADT6, indicating that cyclization can maintain the peptide activity. The alanine residue deletion in ADTC5 does not reduce its activity compared to ADTC1 peptide, suggesting that the alanine residue does not have an important role in the activity of the peptide. In contrast, ADTC6 peptide does not have activity in inhibiting the junction resealing, indicating that the valine residue is important for peptide activity. ADTC5 inhibits the junction resealing of MDCK cell monolayers in a concentration-dependent manner with the saturation concentration above 0.4 mM and IC50 around 0.3 mM. Under the current experimental conditions, ADTC5 improves the delivery of 14C-mannitol to the brain about two fold compared to the vehicle negative control in the in situ rat brain perfusion model. Furthermore, ADTC5 peptide does not enhance the BBB passage of large polyethylene glycol molecules (i.e., PEG-1500 and PEG-40000) in an in situ rat brain perfusion model. In conclusion, formation of cyclic peptides can maintain cadherin peptide ability to modulate intercellular junctions of the BBB, and the primary sequence of ADT peptides is important for their biological activity

Modulation of Intercellular Junctions by Cyclic-ADT Peptides as a Method to Reversibly Increase Blood-Brain Barrier Permeability

It is challenging to deliver molecules to the brain for diagnosis and treatment of brain diseases. This is primarily due to the presence of the blood-brain barrier (BBB), which restricts the entry of many molecules into the brain. In this study, cyclic ADT peptides (ADTC1, ADTC5, and ADTC6) have been shown to modify the BBB to enhance the delivery of marker molecules (e.g., 14C-mannitol, Gd-DTPA) to the brain via the paracellular pathways of the BBB. The hypothesis is that these peptides modulate cadherin interactions in the adherens junctions of the vascular endothelial cells forming the BBB to increase paracellular drug permeation. In vitro studies indicated that ADTC5 had the best profile to inhibit adherens junction resealing in MDCK cell monolayers in a concentration-dependent manner (IC50 = 0.3 mM) with a maximal response at 0.4 mM. Under the current experimental conditions, ADTC5 improved the delivery of 14C-mannitol to the brain about twofold compared to the negative control in the in situ rat brain perfusion model. Furthermore, ADTC5 peptide increased in vivo delivery of Gd-DTPA to the brain of Balb/c mice when administered intravenously (i.v.). In conclusion, ADTC5 has the potential to improve delivery of diagnostic and therapeutic agents to the brain

UPAYA PENINGKATAN KELARUTAN SENYAWA MH2011 DENGAN PELARUT PROPILEN GLIKOL

MH2011 [1-[4-hydroxynaphthalen-1-yl]-3-(4-hydroxyphenyl) urea] is a new compound that is synthesized from urea staring material urea combined with 4- amino-1-4-amino-1-naphthol and p-aminophenols. Research has been conducted to determine the solubility of compound MH2011 in solvents of water and an increase in solubility using the method cosolvent. MH2011 solubility increases 8.6 times as much on the use of cosolvent ethanol with levels of 7.0% from the total volume of the solvent used. It is less satisfying because ethanol is a common cosolvent for use, therefore try to use alternative to replace cosolvent ethanol. Alternative cosolven used are propylene glycol. On the use of rates of 7.0% propylene glycol not ethanol can replace as kosolvent, but when cosolvent is raised levels of compound solubility profile MH2011 will go up and follow the pattern of non linear