Investigating the Effect of Esterification on Retinal Pigment Epithelial Uptake Using Rhodamine B Derivatives

Abstract

This study investigated the effects of esterification and increased lipophilicity on cellular penetration, accumulation and retention in ARPE-19-nic cells using ester functionalized rhodamine B dyes. Methods: Rhodamine B was esterified to generate four dyes with increasing lipophilicity. Cellular uptake, retention and mitochondrial localization were investigated in vitro using ARPE-19-nic cells using direct intracellular and extracellular and mitochondrial fluorescence quantitation, confocal and high-resolution live cell imaging and colocalization with Mito-GFP. Results: Cellular penetrance, mitochondrial accumulation, and retention of the esterified dyes were increased in ARPE-19-nic cells compared with the nonesterified parent dye by direct fluorescence quantitation. Imaging demonstrated intracellular accumulation was confined to mitochondria as confirmed by colocalization with Mito-GFP. Conclusions: Esterification is an effective way to increase lipophilicity of a dye to improve cellular penetration of chemical entities. These observations may be key to improving retinal drug delivery for retinal pigment epithelium-based diseases. Translational Relevance: Understanding the intracellular distribution of drugs into retinal pigment epithelium cells is a critical component for identifying potential therapies for retinal pigment epithelium-based diseases.

Synthesis and In Vitro Activity of Novel Melphalan Analogs in Hematological Malignancy Cells

“…Thus, when explaining the different cytotoxic activities of the analyzed compounds, the size, structure, and ring geometry of the attached amine should be taken into account. There have also been reports in the literature that esterification can increase bioavailability and cellular penetration [21][22][23][24]. In addition, other in vitro studies have shown that amidine analogs of melphalan reduce the number of estrogen receptor-positive and estrogen receptor-free breast cancer cells [25,26].…”