Ing groups (Fmoc and Mtt) was used, which enabled the conjugation

Ing groups (Fmoc and Mtt) was used, which enabled the conjugation of TPP+ and a-CEHC (Figure 1). The masked lysine was coupled onto the Rink Amide MBHA resin. HBTU and HOBt were used to enhance the coupling rate [55,56,57]. The Fmoc was then deprotected to allow for (3-carboxypropyl)TPP+ conjugation through its carboxylic acid group forming an amide bond. The Mtt protecting group was then removed. The removal of the protecting group enabled the carboxylic acid on a-CEHC side chain to form an amide bond with the lysine linker. The final product, TPP+-Lysine-a-CEHC (MitoCEHC), was then released from the resin via treatment with 95 TFA. The final product was characterized by MALDI-TOF mass spectrometry (Figure 2). The molecular weight peak was at 736.39, which corresponds to the expected peak for the MitoCEHC generated by ChemDraw software (PerkinElmer Informatics, Cambridge, MA). The mass spectrometry data also shows virtually no trace of by-products, reagents or synthetic intermediates. The ability 18325633 of final product (MitoCEHC) to diminish oxidative stress was examined in vitro. Oxidative stress is defined as the overproduction of oxidizing chemical species and the Oltipraz failure toeradicate their excess by enzymatic or non-enzymatic antioxidants. Elevation in ROS production is a factor in the etiology of cardiovascular disease by modifying lipids, proteins, and nucleic acids [58]. To further explore the antioxidant activity of the conjugated MitoCEHC, the oxidation (and hence fluorescence) of CM-H2DCFDA was measured (Figure 3). The H2DCFDA derivative with a thiol-reactive chloromethyl group was used due to its better retention in live cells than H2DCFDA. This derivative is retained better in cells because of its ability to bind covalently to intracellular components. BAEC were incubated with low (5 mM) and high (25 mM) glucose concentrations. The cells incubated under hyperglycemic conditions showed an increase in ROS production, which is mainly in the mitochondria [59]. Flow cytometry data also showed decrease in ROS production in the hyperglycemic cells treated with MitoCEHC. a-CEHC conjugated to TPP+ via a lysine linker (MitoCEHC) showed a stronger effect than a-CEHC alone (Figure 3). These results confirm the importance of mitochondria targeting as a strategy to diminish mitochondrial oxidative stress. In an effort to investigate if the TPP+ conjugation to a-CEHC via a lysine linker would increase mitochondrial targeting, an in vivo experiment was performed. Since TPP+ conjugates are orally bioavailable when fed to mice [60], highly insulin resistant db/db mice were provided with 200 mM of the MitoCEHC in their drinking water. Although there is no direct correlation of dosing of vitamin E-like compounds between mice and humans, MitoCEHC doses selected in this study were based on maximalFigure 2. Mass Spectrometry and structure of MitoCEHC (8). The MALDI-TOF Mass Spectrometry of the final product from resin cleavage shows a molecular weight peak at 736.39 m/z. In addition, the structure of MitoCEHC (8) was created using ChemDraw Ultra software, with a calculated m/z for C44H55N3O5P+ of 736.39 (100 ), which corresponds to the Mass Spectrometry results. doi:10.1371/journal.pone.0053272.gSynthesis of MK8931 Mitochondrially Targeted Alpha-CEHC0.77560.137 mg/0.1 g of mitochondria while the plasma concentration was 1.7860.305 mg/ml. The untreated mice showed no trace of MitoCEHC in the isolated mitochondria or plasma. In addition to its antioxidant poten.Ing groups (Fmoc and Mtt) was used, which enabled the conjugation of TPP+ and a-CEHC (Figure 1). The masked lysine was coupled onto the Rink Amide MBHA resin. HBTU and HOBt were used to enhance the coupling rate [55,56,57]. The Fmoc was then deprotected to allow for (3-carboxypropyl)TPP+ conjugation through its carboxylic acid group forming an amide bond. The Mtt protecting group was then removed. The removal of the protecting group enabled the carboxylic acid on a-CEHC side chain to form an amide bond with the lysine linker. The final product, TPP+-Lysine-a-CEHC (MitoCEHC), was then released from the resin via treatment with 95 TFA. The final product was characterized by MALDI-TOF mass spectrometry (Figure 2). The molecular weight peak was at 736.39, which corresponds to the expected peak for the MitoCEHC generated by ChemDraw software (PerkinElmer Informatics, Cambridge, MA). The mass spectrometry data also shows virtually no trace of by-products, reagents or synthetic intermediates. The ability 18325633 of final product (MitoCEHC) to diminish oxidative stress was examined in vitro. Oxidative stress is defined as the overproduction of oxidizing chemical species and the failure toeradicate their excess by enzymatic or non-enzymatic antioxidants. Elevation in ROS production is a factor in the etiology of cardiovascular disease by modifying lipids, proteins, and nucleic acids [58]. To further explore the antioxidant activity of the conjugated MitoCEHC, the oxidation (and hence fluorescence) of CM-H2DCFDA was measured (Figure 3). The H2DCFDA derivative with a thiol-reactive chloromethyl group was used due to its better retention in live cells than H2DCFDA. This derivative is retained better in cells because of its ability to bind covalently to intracellular components. BAEC were incubated with low (5 mM) and high (25 mM) glucose concentrations. The cells incubated under hyperglycemic conditions showed an increase in ROS production, which is mainly in the mitochondria [59]. Flow cytometry data also showed decrease in ROS production in the hyperglycemic cells treated with MitoCEHC. a-CEHC conjugated to TPP+ via a lysine linker (MitoCEHC) showed a stronger effect than a-CEHC alone (Figure 3). These results confirm the importance of mitochondria targeting as a strategy to diminish mitochondrial oxidative stress. In an effort to investigate if the TPP+ conjugation to a-CEHC via a lysine linker would increase mitochondrial targeting, an in vivo experiment was performed. Since TPP+ conjugates are orally bioavailable when fed to mice [60], highly insulin resistant db/db mice were provided with 200 mM of the MitoCEHC in their drinking water. Although there is no direct correlation of dosing of vitamin E-like compounds between mice and humans, MitoCEHC doses selected in this study were based on maximalFigure 2. Mass Spectrometry and structure of MitoCEHC (8). The MALDI-TOF Mass Spectrometry of the final product from resin cleavage shows a molecular weight peak at 736.39 m/z. In addition, the structure of MitoCEHC (8) was created using ChemDraw Ultra software, with a calculated m/z for C44H55N3O5P+ of 736.39 (100 ), which corresponds to the Mass Spectrometry results. doi:10.1371/journal.pone.0053272.gSynthesis of Mitochondrially Targeted Alpha-CEHC0.77560.137 mg/0.1 g of mitochondria while the plasma concentration was 1.7860.305 mg/ml. The untreated mice showed no trace of MitoCEHC in the isolated mitochondria or plasma. In addition to its antioxidant poten.