Selective Delivery of Dicarboxylates to Mitochondria by Conjugation to a Lipophilic Cation via a Cleavable Linker

Abstract

Many mitochondrial metabolites and bioactive molecules contain two carboxylic acid moieties that make them unable to cross biological membranes. Hence, there is considerable interest in facilitating the uptake of these molecules into cells and mitochondria to modify or report on their function. Conjugation to the triphenylphosphonium (TPP) lipophilic cation is widely used to deliver molecules selectively to mitochondria in response to the membrane potential. However, permanent attachment to the cation can disrupt the biological function of small dicarboxylates. Here, we have developed a strategy using TPP to release dicarboxylates selectively within mitochondria. For this, the dicarboxylate is attached to a TPP compound via a single ester bond, which is then cleaved by intramitochondrial esterase activity, releasing the dicarboxylate within the organelle. Leaving the second carboxylic acid free also means mitochondrial uptake is dependent on the pH gradient across the inner membrane. To assess this strategy, we synthesized a range of TPP monoesters of the model dicarboxylate, malonate. We then tested their mitochondrial accumulation and ability to deliver malonate to isolated mitochondria and to cells, in vitro and in vivo . A TPP–malonate monoester compound, TPP 11 –malonate, in which the dicarboxylate group was attached to the TPP compound via a hydrophobic undecyl link, was most effective at releasing malonate within mitochondria in cells and in vivo . Therefore, we have developed a TPP–monoester platform that enables the selective release of bioactive dicarboxylates within mitochondria.

Structural basis for a complex I mutation that blocks pathological ROS production

“…Consistent with this model, the ND6-P25L mutant mouse is protected against cardiac IR injury; it exhibits no change in succinate metabolism, but a substantial decrease in mitochondrial ROS production. Previously, strategies to inhibit succinate accumulation and/or oxidation during IR injury 18,28,[34][35][36][37] have also afforded protection against cardiac IR injury, as has inhibition of complex I catalysis [38][39][40] , albeit by using inhibitors that act in both directions and thereby prevent recovery of normal activity following reperfusion. The ND6-P25L mouse model has thus allowed the precise role of complex I in IR injury to be defined and will now provide crucial opportunities to explore the consequences of RET and mitochondrial ROS production through RET in further physiological settings.…”

A Mitochondria-Targeted Phenylbutyric Acid Prodrug Confers Drastically Improved Anticancer Activities

“…■ EXPERIMENTAL SECTION Chemicals and Materials. 1 H and 13 C NMR spectra were recorded on an Agilent 400 or 600 MR spectrometer at ambient temperature. Chemical shifts were reported in parts per million (ppm), and the residual solvent peak was used as an internal reference: 1 H NMR (CDCl 3 δ 7.26; DMSO-d 6 δ 2.50), 13 C NMR (CDCl 3 δ 77.0; DMSO-d 6 δ 39.6).…”

“…7−11 To enhance the exposure of anticancer drugs in mitochondria, they are often selectively delivered inside the mitochondria by linking to mitochondria vectors, which are membrane permeable and could drive the selective accumulation of the attached drugs within the mitochondria in cells and in vivo. 12,13 The triphenylphosphonium cation (TPP + ) is the most widely used mitochondria-targeting vector due to its straightforward chemical synthesis and high targeting efficiency, as well as the relative stability in biological systems. 14−16 Because of the negative membrane potential of the inside plasma and mitochondrial inner membrane, positively charged TPP + compounds tend to accumulate stepwise against the concentration gradient in the cell cytosol followed by the mitochondrial matrix, which could achieve >100−1000-fold uptake inside the mitochondria as compared with extracellular medium.…”

Hetero-Trifunctional Malonate-Based Nanotheranostic System for Targeted Breast Cancer Therapy

“…Hydrolysis of esters resulted in acidfunctionalized core−shell nanoparticle for functionalization. 7 In another demonstration, Liu et al synthesized PLA-PEG-PLL-DTPA and PLA-PEG-PLL biotin for chelation of Gd and targeting, respectively. Later, paclitaxel was physically encapsulated into the core for the development of a targeted micellar system for pancreatic cancer.…”

“…For instance, silica-coated Fe 3 O 4 magnetic nanoparticles were surface-decorated with diethyl malonate. Hydrolysis of esters resulted in acid-functionalized core–shell nanoparticle for functionalization . In another demonstration, Liu et al synthesized PLA-PEG-PLL-DTPA and PLA-PEG-PLL biotin for chelation of Gd and targeting, respectively.…”