Phospholipid Cyclosporine Prodrugs Targeted at Inflammatory Bowel Disease (IBD) Treatment: Design, Synthesis, and in Vitro Validation

Abstract

Novel phospholipid (PL)‐cyclosporine conjugates were prepared and studied as potential prodrugs for inflammatory bowel disease (IBD). Our approach relies on phospholipase A2 (PLA2), which is overexpressed in the inflamed intestinal tissues, as the prodrug activator to potentially release cyclosporine at the site of inflammation. PL‐cyclosporine prodrug conjugates with methylene linkers of various lengths between the sn‐2 position of the PL and cyclosporine were synthesized and evaluated for in vitro activation. Surprisingly, despite previous work indicating that conjugates with six methylene linkers between the lipid and drug would suffer rapid enzymatic hydrolysis, with cyclosporine this was not observed. However, compounds with longer linkers (n=10, 12 methylene units) display complete release of the drug by PLA2‐catalyzed hydrolysis, thus demonstrating the importance and profound impact of structural fine‐tuning. This study represents a proof‐of‐concept for our hypothesis and a first step towards a truly targeted IBD treatment with cyclosporine that could be administered throughout the GI tract.

Prodrug-Based Targeting Approach for Inflammatory Bowel Diseases Therapy: Mechanistic Study of Phospholipid-Linker-Cyclosporine PLA2-Mediated Activation

“…We have previously used this approach in the in-vitro proof-of-concept studies for PL-based prodrugs of diclofenac and indomethacin [ 24 , 25 ]. The structure of PLC prodrugs and preliminary in-vitro studies are described in our previous work [ 26 ]. The PLC designed prodrug consists of cyclosporine, bound to the sn-2 position of the PL through a linker that mimics the fatty acid substrate.…”

“…The PLC designed prodrug consists of cyclosporine, bound to the sn-2 position of the PL through a linker that mimics the fatty acid substrate. The synthesis of four PLC prodrug is detailed in our previous work [ 26 ]. The NMR data specification of the 2 PLC prodrugs used in this study are seen in Figures S1 and S2 .…”

“…In our previous work, we have developed a new drug targeting approach, a PL-based prodrug approach [ 24 , 25 ]. Most recently, we have developed a library of PL-prodrugs containing PL linked to the cyclosporine through an alkyl linker [ 26 ]. These prodrugs differ in the number of the CH 2 - units (i.e., the length of the linker).…”

“…These prodrugs differ in the number of the CH 2 - units (i.e., the length of the linker). The synthesis of the phospholipid-linker-cyclosporine (PLC) prodrugs includes two step condensation of the PL to the cyclosporine through diacyl chloride linkers with diverse lengths [ 26 ]. In these PLC prodrugs the fatty acid within the sn -2 position of the PL is replaced by cyclosporine-linker moiety.…”

“…This work elucidates mechanistic background of prodrug activation and dynamics. Our preliminary in-vitro studies demonstrated that the chemical link (carbonic linker) between the cyclosporine and the PL affects the level of recognition and activation by PLA 2 [ 26 ]. In this work, we aimed to further explore the effect of different levels of the PLA 2 enzyme on the activation of different PLC prodrugs.…”