Phospholipid-Based Prodrugs for Colon-Targeted Drug Delivery: Experimental Study and In-Silico Simulations.

Milica Markovic,Shimon Ben-Shabat,Ellen M Zimmermann,Arik Dahan,Aaron Aponick,Igor Kurnikov,Shahar Keinan

doi:10.3390/pharmaceutics11040186

Milica Markovic, Shimon Ben-Shabat + Show 5 more

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https://doi.org/10.3390/pharmaceutics11040186

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Abstract

In ulcerative colitis (UC), the inflammation is localized in the colon, and one of the successful strategies for colon-targeting drug delivery is the prodrug approach. In this work, we present a novel phospholipid (PL)-based prodrug approach, as a tool for colonic drug targeting in UC. We aim to use the phospholipase A2 (PLA2), an enzyme that is overexpressed in the inflamed colonic tissues of UC patients, as the PL-prodrug activating enzyme, to accomplish the liberation of the parent drug from the prodrug complex at the specific diseased tissue(s). Different linker lengths between the PL and the drug moiety can dictate the rate of activation by PLA2, and subsequently determine the amount of free drugs at the site of action. The feasibility of this approach was studied with newly synthesized PL-Fmoc (fluorenylmethyloxycarbonyl) conjugates, using Fmoc as a model compound for testing our hypothesis. In vitro incubation with bee venom PLA2 demonstrated that a 7-carbon linker between the PL and Fmoc has higher activation rate than a 5-carbon linker. 4-fold higher colonic expression of PLA2 was demonstrated in colonic mucosa of colitis-induced rats when compared to healthy animals, validating our hypothesis of a colitis-targeting prodrug approach. Next, a novel molecular dynamics (MD) simulation was developed for PL-based prodrugs containing clinically relevant drugs. PL-methotrexate conjugate with 6-carbon linker showed the highest extent of PLA2-mediated activation, whereas shorter linkers were activated to a lower extent. In conclusion, this work demonstrates that for carefully designed PL-drug conjugates, PLA2 overexpression in inflamed colonic tissues can be used as prodrug-activating enzyme and drug targeting strategy, including insights into the activation mechanisms in a PLA2 binding site.

Highlights

Prodrugs are derivatives of active drug moieties with little or no pharmacological effect, which undergo enzymatic and/or chemical conversion in the body into the active parent drug in order to accomplish an anticipated pharmacological effect [1,2]
Lipidic prodrugs consist of the drug moiety covalently bound to the lipid moiety, such as a fatty acid, triglyceride, steroid, or phospholipid (PL) [7,8]
We previously proposed a PL-prodrug design that consists of PL and sn-2 positioned drug moiety connected through a carbonic linker [32,38,39,40,41]

Summary

Introduction

Prodrugs are derivatives of active drug moieties with little or no pharmacological effect, which undergo enzymatic and/or chemical conversion in the body into the active parent drug in order to accomplish an anticipated pharmacological effect [1,2]. The prodrug approach is often employed in order to overcome poor physicochemical properties and improve biopharmaceutical performance (i.e., absorption, distribution, metabolism, and excretion (ADME) properties) [3]. Prodrugs can be designed to overcome formulation obstacles and promote simpler administration, improve the effectiveness of the drug, enable site-specific drug delivery, and reduce toxicity [4,5]. An advantage of lipidic prodrugs is that a carefully designed prodrug can be incorporated into the physiological metabolic pathways for lipids and cross the barriers in the body, which are difficult to overcome otherwise

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