Presence Of Chenodeoxycholic Acid Research Articles

Photovoltaic performance enhancement via cocktail co-sensitization of D–A–π–A and D–π–A–π–A dyes in dye-sensitized solar cells

A novel organic dye (BIM37) featured with donor–auxiliary acceptor–π–acceptor (D–A–π–A) structure based on an acridine π–bridge has been designed and synthesized for dye-sensitized solar cells (DSSCs). Unlike the acridine-based D–π–A–π–A dyes (BIM25 and BIM26), BIM37 was obtained by inserting an auxiliary acceptor between the donor and π–bridge units. This modification leads to a significant red shift in the absorption spectrum compared to its counterparts. Thus, the DSSCs based on BIM37 achieved a power conversion efficiency (PCE) of 5.03%, which is higher than that of BIM25 (3.76%) or BIM26 (4.56%). To further improve the photovoltaic performance, the cocktail co-sensitization strategy was applied. In the presence of chenodeoxycholic acid (CDCA) as a co-adsorbent, the co-sensitized DSSC based on BIM37+BIM26 showed a high efficiency of 6.30%. This performance is superior to individual DSSCs with and without CDCA. The results show that molecular engineering for co-sensitization may be an effective strategy to improve the performance of DSSCs.

Ferrocene Appended D-π-A chromophores for Dye-Sensitized Solar Cells: Synthesis, Photophysical, Effect of Co-adsorbent on Photovoltaic Efficiencies and DFT studies

A new ferrocene conjugated donor–π–acceptor type of dyes 1 and 2 were synthesized and characterized using different spectroscopic techniques (FT-IR, NMR, and ESI-mass). The intramolecular charge transfer process of both the dyes were analysed using the solvatochromic method, which reveals positive solvatochromism due to its well stabilization in the excited states than in the ground states. The electrochemical behavior of the dyes 1 and 2 were carried out by the cyclic voltammetric technique, which shows quasi-reversible in nature, and the potentials were further utilized for the band gap calculation with UV–visible data [2.99 eV (1) and 2.88 eV (2)]. The photovoltaic attainments of the dyes 1 and 2 were studied through the dye-sensitized solar cells (DSSCs) in the presence and absence of co-adsorbent like chenodeoxycholic acid (CDCA), which act as an anti-dye aggregation material. The photovoltaic parameters like short circuit current density (Jsc) = 0.067 mA cm2, open circuit voltage (Voc) = 0.444 V, fill factor (FF) = 0.447, and the cell displayed an overall conversion efficiency of 0.013 % for dye 2. In contrast, the power conversion efficiency (PCE) was found to be enhanced to 0.177 % (Jsc = 0.389 mA/cm2, Voc = 0.577 V, FF =0.790), in the presence of chenodeoxycholic acid (CDCA) co-adsorbent. This enhancement in efficiency is due to reduced dye aggregation and increased electron injection in the presence of CDCA. In addition, chromophore 2 has 1.4 times higher efficiencies than 1, attributing to the presence of an additional phenyl group making an efficient intramolecular process of 2. Furthermore, the incident photon to current efficiency (IPCE) and electrochemical impedance spectroscopy (EIS) studies reveal the dye efficiencies were directly proportional to that of the power conversion efficiency (PCE), respectively. Moreover, the electronic structure and electron density distribution analysis were analysed for both dyes 1 and 2 to confirm the intramolecular charge transfer properties using density-functional theory (DFT) and time-dependent density-functional theory (TD-DFT) calculations using the B3LYP/ 6–31+G** level of theory.

Enhancement of photovoltaic performance in ferrocenyl π-extended multi donor-π-acceptor (D-D'-π-A) dyes using chenodeoxycholic acid as a dye co-adsorbent for dye sensitized solar cells.

A new set of multi-donor [ferrocene (D) and methoxyphenyl (D')] conjugated D-D'-π-A based dyes [Fc-(OCH3-Ph)C[double bond, length as m-dash]CH-CH[double bond, length as m-dash]CN-R{R[double bond, length as m-dash]COOH (1) and C6H4-COOH (2)}] were synthesized as sensitizers for dye-sensitized solar cell (DSSC) applications. These dyes were characterized with the aid of analytical and spectroscopic techniques such as FT-IR, HR-Mass, and 1H and 13C NMR. The thermal stability of the dyes 1 and 2 were investigated using thermogravimetric analysis (TGA) and was found to be stable around 180 °C for dye 1 and 240 °C for dye 2. The electronic absorption spectra for sensitizers display major bands between 400 and 585 nm that could be ascribed to an intramolecular charge transfer (ICT) between the electron donor and acceptor to create an efficient charge separation. The redox behaviour of the dyes was determined by cyclic voltammetry, which revealed the one-electron transfer from the ferrocene to ferrocenium ion (Fe2+ ⇌ Fe3+), and potential was utilized to determine the band gap of the dyes (2.16 eV for 1 and 2.12 eV for 2). Further, the carboxylic anchor dyes 1 and 2 have been utilized as photosensitizers in TiO2-based DSSCs with and without co-adsorbance of chenodeoxycholic acid (CDCA), and the photovoltaic performances were studied. The obtained photovoltaic parameters of dye 2 are open-circuit voltage (V oc) = 0.428 V, short-circuit current density (J sc) = 0.086 mA cm-2, the fill factor (FF) = 0.432 and the energy efficiencies (η) = 0.015%, the overall power conversion efficiencies were found to be increased in the presence of CDCA as a co-adsorbent. The photosensitizers with the addition of CDCA show higher efficiencies compared to those in the absence of CDCA, which can prevent the formation of aggregation and increased electron injection of the dyes. Among the dyes, the 4-(cyanomethyl) benzoic acid (2) anchor showed higher photovoltaic performance compared with the cyanoacrylic acid (1) anchor due to the introduction of additional π-linkers and acceptor unit, which enables the lowering of the energy barrier and charge recombination process. In addition, the experimentally observed HOMO and LUMO values were in good agreement with the theoretical calculation by the DFT-B3LYP/6-31+G**/LanL2TZf level of theory.

Effect of chenodeoxycholic acid as dye co-adsorbent and ZnO blocking layer in improving the performance of Rose Bengal dye based dye sensitized solar cells

Effective suppression of dye aggregation on the photoanode surface of dye sensitized solar cells plays a key role in improving solar cell efficiency. Chenodeoxycholic acid (CDCA) is a very popular anti dye aggregation material used in dye sensitized solar cells (DSSC). However, the selection of an improper concentration of CDCA may lead to decreased solar cell efficiency by lowering the open circuit voltage and short circuit current as a consequence of reduced dye loading. The influence of CDCA as a dye co-adsorbent on the performance of DSSCs fabricated using Rose Bengal dye was studied in this paper. The concentration of the CDCA solution was varied to identify the optimum value for the best device performance. Aside from this, the effect of a very thin and compact ZnO blocking layer was also investigated to reduce the charge recombination. With photovoltaic parameters such as short circuit current density (Jsc) = 1.98 mA/cm2, open circuit voltage (Voc) = 0.58 V, and fill factor (FF) = 0.43, the traditional cell displayed an overall conversion efficiency of 0.49%, while the power conversion efficiency was found to be increased to 1.00% (Jsc = 2.80 mA/cm2, Voc = 0.64, FF = 0.58) when CDCA was added at optimised concentration of 8 mM. Reduced dye aggregation and increased electron injection in the presence of CDCA may be accounted for the DSSC's remarkable improvement in the efficiency. Moreover, the combined effect of 8 mM CDCA and the compact ZnO blocking layer dramatically enhanced the efficiency further to 1.22% (Jsc = 3.09 mA/cm2, Voc = 0.66, FF = 60). Electrochemical impedance spectroscopic (EIS) analysis revealed that the addition of CDCA as a co-adsorbent in the dye solution and addition of ZnO blocking layer resulted in significantly improved electron lifetime and reduced electron recombination yielding improved Jsc, Voc and η.

4,5-Diazafluorene ligands and their ruthenium(II) complexes with boronic acid and catechol anchoring groups: design, synthesis and dye-sensitized solar cell applications

Design, synthesis, characterization, and investigation of photovoltaic properties of 4,5-diazafluorene derived diimine ligands (C2, C3) and their ruthenium(II) complexes are reported. FT-IR, 1H NMR, 13C NMR, and mass spectroscopic methods were used to elucidate the structures of these compounds. The effect of the number and nature of anchoring groups attached to these ligands and complexes as sensitizers were evaluated for optical properties and photovoltaic performance in dye-sensitized solar cells (DSSCs). The sensitizers bearing catechol show higher power conversion efficiency (PCE) than the dyes with boronic acid due to better binding of the catechol anchoring group on the TiO2 surface. Among these sensitizers, DSSC based on [Ru(C2)2(NCS)2](PF6)2 having two catechol anchoring groups gives the best PCE of 2.83%, with Jsc = 6.40 mA cm−2, Voc = 0.632 V and FF = 0.70 in the presence of chenodeoxycholic acid (CDCA) as the coadsorbent, which is attributed to broader spectral response and efficient electron injection. These results suggest that dyes bearing two catechol anchoring groups are promising for efficient DSSCs.

5,6,7-Trimethoxy-2-(Methylthio)Quinoline with Different Anchoring Groups: Synthesis And Dye-Sensitized Solar Cell Applications

Two new metal-free organic dyes in D-π-A structure, containing a quinoline π-bridge and malononitrile (4a) and cyanoacrylic acid (4b) as acceptors, were synthesized for the first time to apply dye-sensitized solar cell (DSSC). The structures of these compounds were elucidated by FT-IR, 1H NMR, 13C NMR techniques. The photophysical and photovoltaic properties of the obtained compounds were investigated and compared by current density–voltage (J–V) graphs. Compound 4b containing cyanoacrylic acid as an acceptor reached an open–circuit voltage (Voc) of 0.645 V, short–circuit current density (Jsc) of 6.66 mA cm-2 and fill factor (FF) of 0.70 in the presence of chenodeoxycholic acid (CDCA), showing a power conversion efficiency (PCE) of 3.01%. It is also observed that the incorporation of thiomethyl group to the structure instead of methoxy group increases the PCE.

The improvement of photovoltaic performance of quinoline-based dye-sensitized solar cells by modification of the auxiliary acceptors

Three new dyes containing diphenylamine as electron donor, benzene (BIM1), benzothiadiazole (BTD) (BIM2) and N-ethylhexylbenzotriazole (BTZ) (BIM3) as auxiliary electron acceptors, quinoline as π-bridge and cyanoacrylic acid as anchoring group were synthesized in D-A-π-A structure for use in dye-sensitized solar cells (DSSCs). The optical, electrochemical, theoretical and photovoltaic methods were performed to understand the auxiliary acceptor influence on the performance of these dyes. Compared to the other dyes, the DSSC with dye BIM3 slightly increases the open circuit voltage (Voc) owing to the retardation of charge recombination by BTZ. However, replacement of benzene or BTZ by BTD unit causes a large red shift of the absorption spectra, leading BIM2 cell to produce the highest short circuit current density (Jsc). Thus, among the three D-A-π-A dyes, BIM2 is determined to be the most efficient dye, which reached a Voc of 0.627 V and Jsc of 11.53 mA cm–2, corresponding to an overall power conversion efficiency of 5.21 % in the presence of chenodeoxycholic acid (CDCA) as the coadsorbent. These results suggest that the insertion of benzothiadiazole as auxiliary acceptor into quinoline-based D-A-π-A dyes can effectively improve photovoltaic performance of DSSCs.

Drug Discovery and Repurposing Inhibits a Major Gut Pathogen-Derived Oncogenic Toxin.

Objective: The human intestinal microbiome plays an important role in inflammatory bowel disease (IBD) and colorectal cancer (CRC) development. One of the first discovered bacterial mediators involves Bacteroides fragilis toxin (BFT, also named as fragilysin), a metalloprotease encoded by enterotoxigenic Bacteroides fragilis (ETBF) that causes barrier disruption and inflammation of the colon, leads to tumorigenesis in susceptible mice, and is enriched in the mucosa of IBD and CRC patients. Thus, targeted inhibition of BFT may benefit ETBF carrying patients.Design: By applying two complementary in silico drug design techniques, drug repositioning and molecular docking, we predicted potential BFT inhibitory compounds. Top candidates were tested in vitro on the CRC epithelial cell line HT29/c1 for their potential to inhibit key aspects of BFT activity, being epithelial morphology changes, E-cadherin cleavage (a marker for barrier function) and increased IL-8 secretion.Results: The primary bile acid and existing drug chenodeoxycholic acid (CDCA), currently used for treating gallstones, cerebrotendinous xanthomatosis, and constipation, was found to significantly inhibit all evaluated cell responses to BFT exposure. The inhibition of BFT resulted from a direct interaction between CDCA and BFT, as confirmed by an increase in the melting temperature of the BFT protein in the presence of CDCA.Conclusion: Together, our results show the potential of in silico drug discovery to combat harmful human and microbiome-derived proteins and more specifically suggests a potential for retargeting CDCA to inhibit the pro-oncogenic toxin BFT.

Role of hexyloxy groups in zinc phthalocyanines bearing sulfonic acid anchoring groups for dye-sensitized solar cells

Zinc phthalocyanine dyes bearing four sulfonic acid anchoring groups with (A-ZnPc) and without (H-ZnPc) four chloro and eight hexyloxy groups were used as sensitizers for dye-sensitized solar cells (DSSCs). The dyes were investigated in terms of their optical, electrochemical and photovoltaic properties. The presence of these groups in dye A-ZnPc resulted in both red-shifted absorption and decreased dye aggregation, which are beneficial for the improvement of device performance. In the presence of chenodeoxycholic acid (CDCA) as a coadsorbent, the DSSC based on H-ZnPc shows a power conversion efficiency (PCE) of 0.96%, which is improved by [Formula: see text]40% as compared to the device without CDCA. However, the PCE of an A-ZnPc-based device with CDCA slightly enhances from 1.15% (without CDCA) to 1.22%, indicating that the bulky hexyloxy groups with large steric hindrance can effectively suppress aggregation of the adsorbed dye. The results showed that the zinc phthalocyanine dye bearing bulky hexyloxy groups is a promising candidate to construct efficient coadsorbent-free DSSCs.

Synthesis of non-peripheral thioanisole-substituted phthalocyanines: Photophysical, electrochemical, photovoltaic, and sensing properties

Abstract This work reports on the synthesis, characterization, photophysical, electrochemical, photovoltaic and sensing properties of non-peripherally tetra 4-(methylthio)phenoxy substituted metal-free (2), Zn(II) (3) and Co(II) (4) phthalocyanine derivatives. Confirmation of the synthesized phthalocyanine structures which have the good solubility in organic solvents, performed with a combination of elemental analysis, FTIR, 1H NMR, 13C NMR, UV–vis and MALDI-MS spectral data. Electrochemical measurements exhibit that the complex (4) shows the redox reactions taking place on both metal center and the ring while the phthalocyanines (2) and (3) give only ring-based redox reactions. All the complexes were examined for utilization in dye-sensitized solar cells (DSSCs) in the presence of chenodeoxycholic acid and the highest power conversion efficiency was achieved for the complex (3), as 1.09%. The interaction of phthalocyanines (2) and (3) with Ag+ and Pd2+ ions and their aggregation properties (H- or J- Aggregation) were investigated by UV–vis spectroscopy. Photophysical (fluorescence quantum yield) properties of the complexes (2) and (3) were reported in different solvents, such as tetrahydrofuran (THF) and dimethyl sulfoxide (DMSO). The results of spectral measurements in these solvents showed that ΦF value of the complexes (2) and (3) were found to be lower than the unsubstituted ZnPc.

Steroid Biomarkers Revisited - Improved Source Identification of Faecal Remains in Archaeological Soil Material.

Steroids are used as faecal markers in environmental and in archaeological studies, because they provide insights into ancient agricultural practices and the former presence of animals. Up to now, steroid analyses could only identify and distinguish between herbivore, pig, and human faecal matter and their residues in soils and sediments. We hypothesized that a finer differentiation between faeces of different livestock animals could be achieved when the analyses of several steroids is combined (Δ5-sterols, 5α-stanols, 5β-stanols, epi-5β-stanols, stanones, and bile acids). We therefore reviewed the existing literature on various faecal steroids from livestock and humans and analysed faeces from old livestock breed (cattle, horse, donkey, sheep, goat, goose, and pig) and humans. Additionally, we performed steroid analyses on soil material of four different archaeological periods (sites located in the Lower Rhine Basin, Western Germany, dating to the Linearbandkeramik, Urnfield Period / Bronze Age, Iron Age, Roman Age) with known or supposed faecal inputs. By means of already established and newly applied steroid ratios of the analysed faeces together with results from the literature, all considered livestock faeces, except sheep and cattle, could be distinguished on the basis of their steroid signatures. Most remarkably was the identification of horse faeces (via the ratio: epi-5β-stigmastanol: 5β-stigmastanol + epicoprostanol: coprostanol; together with the presence of chenodeoxycholic acid) and a successful differentiation between goat (with chenodeoxycholic acid) and sheep/cattle faeces (without chenodeoxycholic acid). The steroid analysis of archaeological soil material confirmed the supposed faecal inputs, even if these inputs had occurred several thousand years ago.

Dye-sensitized solar cells, based on electrochemically functionalized porphyrins

The applications of electrochemically functionalized porphyrin have been considered in dye-sensitized solar cells (DSSCs). A porphyrin-catechol derivative has been electrochemically functionalized with a sulfur-contained, 2-mercaptobenzothiazole moiety and was tested as dye. Catechol moiety acts as the anchoring group in these types of dyes. The IPCE result confirmed that photocurrents for DSSCs based on porphyrin-catechol dyes are mainly generated by an indirect electron injection pathway (Type I mechanism).The cells made with this porphyrin were stable and showed no significant desorption of dye from the TiO2 surface after days. Electrochemically functionalized porphyrin-catechol showed almost 100 % enhancement in efficiency compared to bare porphyrin-catechol. The effect of different additives on cell performance was also tested. Electrochemically functionalized porphyrin catechol, in the presence of chenodeoxycholic acid had a record performance with a conversion efficiency of 0.6 % under AM 1.5 irradiation. A porphyrincatechol derivative has been prepared via electrosynthesis with a sulfur contained, 2-mercaptobenzothiazole moiety and was tested as dye. Catechol moiety acts as the anchoring group in these types of dyes. The IPCE result confirmed that photocurrents for DSSCs based on porphyrincatechol dyes are mainly generated by an indirect electron-injection pathway (Type I mechanism).

Role of PPARα in the attenuation of bile acid-induced apoptosis by omega-3 long-chain polyunsaturated fatty acids in cultured hepatocytes.

Omega-3 long-chain polyunsaturated fatty acids (ω3PUFA) have been shown to be antiinflammatory in the attenuation of hepatocellular injury. Peroxisome proliferator-activated receptor alpha (PPARα) is a nuclear receptor transcription factor that inhibits the activation of nuclear factor κB, thereby repressing inflammation, and ωPUFA are PPARα ligands. The purpose of this study was to determine if ω3PUFA attenuate bile acid-induced apoptosis via PPARα. Human hepatocellular carcinoma (HepG2) cells were treated with chenodeoxycholic acid (CDCA) ± ω3PUFA. Activation of PPARα was evaluated, and expression of PPARα, farnesoid X receptor, liver X receptor alpha (LXRα), and retinoid X receptor mRNA was evaluated by reverse-transcriptase PCR. PPARα activation was increased in HepG2 cells treated with ω3PUFA, and decreased in the presence of CDCA when compared with untreated cells. PPARα mRNA was reduced by 67% with CDCA and restored to the level of control with ω3PUFA. LXRα mRNA increased twofold with CDCA treatment and was significantly reduced by ω3PUFA. Expression of PPARα, as well as LXRα mRNA levels, was reduced with CDCA treatment and restored with the addition of ω3PUFA. These results suggest that PPARα and LXRα may be mediators by which ω3PUFA attenuate bile acid-induced hepatocellular injury.

Donor–π–acceptor organic hybrid TiO2 interfaces for solar energy conversion

It is reported herein that the co-adsorption of chenodeoxycholic acid (CDCA) with the D–π–A organic dyes (E)-3-(5-(4-(bis(4-(hexyloxy)phenyl)amino)phenyl)thiophen-2-yl)-2-cyanoprop-2-enoic acid (Dye-O) or (E)-3-(5-(4-(bis(4-(hexylthio)phenyl)amino)phenyl)thiophen-2-yl)-2-cyanoprop-2-enoic acid (Dye-S) has a significant influence on the ground state absorption spectra of sensitized TiO2 thin films. In the absence of CDCA, evidence for aggregation was observed at even the lowest measured surface coverages. The presence of CDCA also had a significant and very beneficial influence on the unwanted charge recombination reaction between TiO2(e−) and oxidized cobalt mediators.

Effect of bulky groups in ruthenium heteroleptic sensitizers on dye sensitized solar cell performance

Two novel heteroleptic ruthenium sensitizers, TT204 and TT205, containing bulky substituents at the 4,4-positions of the ancillary 2,2-bipyridine ligand, were synthesized and characterized. They exhibit absorption maxima in the visible region at 520–530 nm due to metal-to-ligand charge transfer (MLCT) transitions. The EHOMO and ELUMO values indicate sufficient driving force for efficient dye regeneration by the iodide/tri-iodide redox electrolyte and efficient electron injection into the TiO2 conduction band following photoexcitation, respectively. The performance of these heteroleptic sensitizers in dye sensitized solar cells was investigated where TiO2 sensitization was carried out both in the presence and absence of chenodeoxycholic acid. The best efficiency among these sensitizers was recorded in the presence of chenodeoxycholic acid which generated a high short circuit current of 18.7 mA cm−2, an open circuit potential of 0.72 V and a fill factor of 73% with a resulting total power conversion efficiency of 9.81% under AM 1.5G 1 sun illumination. Comparison with the reference dye C101 indicates that though bulky groups can prevent aggregation resulting in high photocurrents even in the absence of chenodeoxycholic acid, they can also lead to lower cell voltages due to inefficient dye packing on the TiO2 surface.

Attachment of Protoporphyrin Dyes to Nanostructured ZnO Surfaces: Characterization by Near Edge X-ray Absorption Fine Structure Spectroscopy

The attachment of H2- and metal (Co- and Zn-) protoporphyrin IX molecules to ZnO nanorods and single-crystal surfaces is investigated by Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. The carboxyl groups of the protoporphyrin are found to be essential for anchoring the molecules to ZnO surfaces. The crystallographic orientation of the exposed ZnO face has an influence on the dye immobilization, with the highest uptake observed for the oxygen-terminated ZnO (000-1) surface. The preparation conditions are crucial for the dye immobilization. Under certain preparation conditions, there is a Zn atom exchange between the H2-protoporphyrin and the ZnO surface, i.e., a metalation of H2-protoporphyrin IX to form Zn-protoporphyrin. Moreover, in the presence of chenodeoxycholic acid as coabsorber, the ZnO single-crystal surfaces are etched, as indicated by the loss of the orientation-dependent spectral features. These results help to pinpoint the chemical reactions that are responsible for the poor...

Regulation of VDR expression in rat and human intestine and liver – Consequences for CYP3A expression

The vitamin D receptor (VDR) regulates the expression of drug metabolizing enzymes and transporters in intestine and liver, but the regulation of VDR expression in intestine and liver is incompletely understood. We studied the regulation of VDR mRNA expression by ligands for VDR, farnesoid X receptor (FXR), glucocorticoid receptor (GR) and protein kinase C α (PKCα) in rat and human ileum and liver using precision-cut slices. 1,25(OH) 2D 3 induced VDR expression in rat ileum and liver, and human ileum but not in liver. Chenodeoxycholic acid (CDCA), but not lithocholic acid (LCA) and GW4064 induced VDR mRNA expression in rat ileum and liver. The PKCα activator, phorbol-12-myristate-13-acetate (PMA) induced the expression of VDR in the rat liver, and the induction of VDR by 1,25(OH) 2D 3 and CDCA was inhibited by the PKCα inhibitor, bisindolyl maleimide I (Bis I). These results show that the expression of VDR is likely to be regulated by PKC but not by FXR or VDR activation at least in the rat liver. The VDR mediated induction of its target genes CYP3A1 and CYP3A2 by 1,25(OH) 2D 3 or LCA in the rat ileum was strongly reduced in the presence of CDCA despite the higher VDR expression. Thus, CDCA might potentiate the toxicity of LCA by inhibiting its metabolism.

Effect of different electron donating groups on the performance of dye-sensitized solar cells

A series of organic sensitizers containing identical π-spacers and electron acceptors but different, aromatic amine electron-donating groups, were used in dye-sensitized solar cells to study the effect of the electron donating groups on device performance. The derived photophysical and photovoltaic properties, as well as density functional theory calculations, revealed that the tetrahydroquinoline dye was prone to aggregate upon the surface of titanium dioxide owing to the dye's planar structure. A 45% improvement in efficiency of a tetrahydroquinoline dye based cell was achieved when chenodeoxycholic acid was employed as co-adsorbent. However, the airscrew type of triphenylamine unit and Y type structure of the substituted phenothiazine framework suppressed dye aggregation on titanium dioxide. The efficiency of a phenothiazine dye-based cell fabricated using saturated co-adsorbent in dichloromethane was only 15% greater than that achieved in the absence of co-adsorbent. Electrochemical Impedance Spectroscopy was used to determine the interfacial charge transfer process occurring in solar cells that employed different dyes in both the absence and presence of chenodeoxycholic acid as co-adsorbent.

Dietary procyanidins enhance transcriptional activity of bile acid‐activated FXR in vitro and reduce triglyceridemia in vivo in a FXR‐dependent manner

Consumption of dietary flavonoids has been associated with reduced mortality and risk of cardiovascular disease, partially by reducing triglyceridemia. We have previously reported that a grape seed procyanidin extract (GSPE) reduces postprandial triglyceridemia in normolipidemic animals signaling through the orphan nuclear receptor small heterodimer partner (SHP) a target of the bile acid receptor farnesoid X receptor (FXR). Our aim was to elucidate whether FXR mediates the hypotriglyceridemic effect of procyanidins. In FXR-driven luciferase expression assays GSPE dose-dependently enhanced FXR activity in the presence of chenodeoxycholic acid. GSPE gavage reduced triglyceridemia in wild type mice but not in FXR-null mice, revealing FXR as an essential mediator of the hypotriglyceridemic actions of procyanidins in vivo. In the liver, GSPE downregulated, in an FXR-dependent manner, the expression of the transcription factor steroid response element binding protein 1 (SREBP1) and several SREBP1 target genes involved in lipogenesis, and upregulated ApoA5 expression. Altogether, our results indicate that procyanidins lower triglyceridemia following the same pathway as bile acids: activation of FXR, transient upregulation of SHP expression and subsequent downregulation of SREBP1 expression. This study adds dietary procyanidins to the arsenal of FXR ligands with potential therapeutic use to combat hypertriglyceridemia, type 2 diabetes and metabolic syndrome.

Disruption of an SP2/KLF6 Repression Complex by SHP Is Required for Farnesoid X Receptor-induced Endothelial Cell Migration

The farnesoid X receptor (FXR) signaling pathway regulates bile acid and cholesterol homeostasis. Here, we demonstrate, using a variety of gain- and loss-of-function approaches, a role of FXR in the process of cell motility, which involves the small heterodimeric partner (SHP)-dependent up-regulation of matrix metalloproteinase-9. We use this observation to reveal a transcriptional regulatory mechanism involving the SP/KLF transcription factors, SP2 and KLF6. Small interference RNA-based silencing studies in combination with promoter, gel shift, and chromatin immunoprecipitation assays indicate that SP2 and KLF6 bind to the matrix metalloproteinase-9 promoter and together function to maintain this gene in a silenced state. However, upon activation of FXR, SHP interacts with SP2 and KLF6, disrupting the SP2/KLF6 repressor complex. Thus, together, these studies identify a mechanism for antagonizing Sp/KLF protein repression function via SHP, with this process regulating endothelial cell motility.