Identification of the Role of TGR5 in the Regulation of Leydig Cell Homeostasis

Understanding the regulation of the testicular endocrine function leading to testosterone production is a major objective as the alteration of endocrine function is associated with the development of many diseases such as infertility. In the last decades, it has been demonstrated that several endogenous molecules regulate the steroidogenic pathway. Among them, bile acids have recently emerged as local regulators of testicular physiology and particularly endocrine function. Bile acids act through the nuclear receptor FXRα (Farnesoid-X-receptor alpha; NR1H4) and the G-protein-coupled bile acid receptor (GPBAR-1; TGR5). While FXRα has been demonstrated to regulate testosterone synthesis within Leydig cells, no data are available regarding TGR5. Here, we investigated the potential role of TGR5 within Leydig cells using cell culture approaches combined with pharmacological exposure to the TGR5 agonist INT-777. The data show that activation of TGR5 results in a decrease in testosterone levels. TGR5 acts through the PKA pathway to regulate steroidogenesis. In addition, our data show that TGR5 activation leads to an increase in cholesterol ester levels. This suggests that altered lipid homeostasis may be a mechanism explaining the TGR5-induced decrease in testosterone levels. In conclusion, the present work highlights the impact of the TGR5 signaling pathway on testosterone production and reinforces the links between bile acid signaling pathways and the testicular endocrine function. The testicular bile acid pathways need to be further explored to increase our knowledge of pathologies associated with impaired testicular endocrine function, such as fertility disorders.     

Chenodeoxycholic Acid Has Non-Thermogenic,Mitodynamic Anti-Obesity Effects in an In Vitro CRISPR/Cas9 Model of Bile Acid Receptor TGR5 Knockdown

Bile acids (BA) have shown promising effects in animal models of obesity. However, the said effects are thought to rely on a thermogenic effect, which is questionably present in humans. A previous work has shown that the BA chenodeoxycholic acid (CDCA) can revert obesity and accelerate metabolism in animal and cell culture models. Thus, the aim of this study was to understand if this obesity reduction is indeed thermogenically-dependent. A CRISPR/Cas9 model of TGR5 (BA receptor) knockdown in 3T3-L1 adipocytes was developed to diminish thermogenic effects. Various parameters were assessed, including mitochondrial bioenergetics by Seahorse flux analysis, oxidative stress and membrane potential by fluorometry, intermediary metabolism by NMR, protein content assessment by Western Blot, gene expression by qPCR, and confocal microscopy evaluation of mitophagy. CDCA was still capable, for the most part, of reversing the harmful effects of cellular obesity, elevating mitophagy and leading to the reduction of harmed mitochondria within the cells, boosting mitochondrial activity, and thus energy consumption. In summary, CDCA has a non-thermogenic, obesity reducing capacity that hinges on a healthy mitochondrial population, explaining at least some of these effects and opening avenues of human treatment for metabolic diseases.     

Design,Synthesis, and Structure–Activity Relationships of 3,4,5‐Trisubstituted 4,5‐Dihydro‐1,2,4‐oxadiazoles as TGR5 Agonists

Given its role in the mediation of energy and glucose homeostasis, the G‐protein‐coupled bile acid receptor 1 (TGR5) is considered a potential target for the treatment of type 2 diabetes mellitus and other metabolic disorders. By thorough analysis of diverse structures of published TGR5 agonists, a hypothetical ligand‐based pharmacophore model was built, and a new class of potent TGR5 agonists, based on the novel 3,4,5‐trisubstituted 4,5‐dihydro‐1,2,4‐oxadiazole core, was discovered by rational design. Three distinct synthetic methods for constructing 4,5‐dihydro‐1,2,4‐oxadiazoles and extensive structure–activity relationship studies are reported herein. Compound (R)‐ 54 n , the structure of which was determined by single‐crystal X‐ray diffraction and quantum chemical solid‐state TDDFT‐ECD calculations, showed the best potency, with an EC₅₀ value of 1.4 nM toward hTGR5. Its favorable properties in vitro warrant further investigation.     

Structure–Activity Relationships of Quinoxaline‐Based 5‐HT3A and 5‐HT3AB Receptor‐Selective Ligands

Until recently, discriminating between homomeric 5‐HT₃A and heteromeric 5‐HT₃AB receptors was only possible with ligands that bind in the receptor pore. This study describes the first series of ligands that can discriminate between these receptor types at the level of the orthosteric binding site. During a recent fragment screen, 2‐chloro‐3‐(4‐methylpiperazin‐1‐yl)quinoxaline (VUF10166) was identified as a ligand that displays an 83‐fold difference in [³H]granisetron binding affinity between 5‐HT₃A and 5‐HT₃AB receptors. Fragment hit exploration, initiated from VUF10166 and 3‐(4‐methylpiperazin‐1‐yl)quinoxalin‐2‐ol, resulted in a series of compounds with higher affinity at either 5‐HT₃A or 5‐HT₃AB receptors. These ligands reveal that a single atom is sufficient to change the selectivity profile of a compound. At the extremes of the new compounds were 2‐amino‐3‐(4‐methylpiperazin‐1‐yl)quinoxaline, which showed 11‐fold selectivity for the 5‐HT₃A receptor, and 2‐(4‐methylpiperazin‐1‐yl)quinoxaline, which showed an 8.3‐fold selectivity for the 5‐HT₃AB receptor. These compounds represent novel molecular tools for studying 5‐HT₃ receptor subtypes and could help elucidate their physiological roles.     

Effect of side chain structure on the liquid crystalline properties of polymers bearing cholesterol, dihydrocholesterol and bile acid pendant groups

Four methacrylate derivatives of steroid molecules, namely cholic acid methyl ester, lithocholic acid methyl ester, cholesterol and dihydrocholesterol, were synthesized. A 10-carbon spacer separates the rigid core and the polymerizable methacrylate group. These monomers and their corresponding polymers were characterized for their liquid crystalline properties by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction. It was found that only the compounds bearing the planar cholesterol-based moieties, and not those bearing the esterified bile acid groups, possess liquid crystalline phases. A detailed X-ray study showed that the dihydrocholesterol polymer possesses the same two mesophases as the cholesterol polymer, but with reduced thermal stability.     

聚苯基甲基硅氧烷改性ZSM-5分子筛上的甲苯择形歧化反应

以聚苯基甲基硅氧烷为改性剂,采用化学液相沉积法对ZSM-5分子筛催化剂进行改性修饰,考察改性催化剂的甲苯择形歧化反应性能。采用XRD、BET、NH 3-TPD表征改性催化剂的孔结构和酸性质。结果表明,聚苯基甲基硅氧烷作为改性剂可以增加催化剂的弱酸中心和中强酸中心酸量,同时缩小催化剂的平均孔径,改性程度与改性次数有关。改性催化剂用于甲苯歧化反应可以增加对二甲苯的选择性,对二甲苯选择性的增加程度与改性次数有关,改性次数增多,对二甲苯选择性增加越显著,同时甲苯转化率越低,副反应越多。     

C5抽余液选择性加氢工艺研究

通过对C5抽余液选择性加氢的工艺条件试验,考察了入口温度、氢油体积比、体积空速和反应压力等主要工艺条件对反应转化率的影响。得出适宜的工艺条件:在稀释进料,C5/环己烷为1/2,反应入口温度为44℃,氢油体积比(对原料C5)为500∶1,体积空速(对C5原料)为1.0 h-1,反应压力为基准+2.0 MPa,加氢后的C5组分中二烯烃及炔烃总含量小于1.0%。1 000 h的稳定性实验证明该催化剂具有很好的活性稳定性。     

Shedding light on the poly(5-ethylidene-2-norbornene) microstructural differences: Skeleton rearrangements during polymerization

Here, an attempt is made to study one of the less noticed aspects of the polymerization of 5-ethylidene-2-norbornene (ENB) by nickel α-diimine catalysts. Therefore, several (co)polymerization runs using MMAO-activated binuclear catalyst (BNC) and mononuclear catalyst (MNC) were undertaken. Catalyst activities as high as 561.1 and 925.0 (kg_pol mol⁻¹_Ni h⁻¹) were observed for ENB polymerization by MNC and BNC, respectively. However, the utilization of comonomer (norbornene [NB]) led to a dramatic decline in the catalyst activities, reaching low levels of 69.4 and 144.4 (kg_pol mol⁻¹_Ni h⁻¹), respectively. Structural characterization (NMR and FTIR) corroborated the occurrence of ring opening via β-C elimination and the subsequent β-H elimination. Additionally, tandem transannular polymerization and ring-opening metathesis polymerization of ENB were evidenced. The findings demonstrated that the transannular polymerization prevailed during the polymerization, albeit the MNC catalyst showed a higher contribution of ring opening via β-C elimination. Importantly, comonomer (NB) was displayed to alter the governing polymerization mechanism. According to DMTA analysis, the structures of the monomer and catalyst were found to significantly influence the polymer damping behavior and microstructure heterogeneity. That is, the NB-ENB copolymer obtained by MNC exhibited the lowest T_g value and highest tan δ along with the diminished microstructure heterogeneity.     

5-磺基水杨酸的吸附研究

用丙烯酸系树脂XAD-7和超高交联树脂NDA-150对5-磺基水杨酸进行了吸附研究。结果表明,在无甲醇的水溶液中,超高交联树脂NDA-150对5-磺基水杨酸有明显的吸附优势,其吸附量大于丙烯酸系树脂XAD-7;在有甲醇存在的溶液中,超高交联树脂NDA-150的吸附能力明显下降,而丙烯酸系树脂XAD-7的吸附能力却几乎不受甲醇的影响。范德华力是超高交联树脂NDA-150在吸附过程中的主要作用力,而氢键是丙烯酸系树脂XAD-7在吸附过程中的主要作用力。     

温控膦配体及其在液／液两相催化中的研究进展

介绍了基于温控膦配体的新型液／液两相催化体系温控相转移催化（TRPTC）和温控相分离催化（TPSC）的基本原理。首次将温控膦配体的合成方法进行分类，分为环氧乙烷加成法和醇解反应合成法两大类并分别加以介绍，全面总结了温控膦配体在各类液／液两相催化反应中的应用。     

2-甲基-5-硝基咪唑合成工艺研究及应用

2-甲基-5-硝基咪唑是一种重要的有机精细化工中间体,本文讨论了近年来国内对其合成工艺的改进方法,并简单介绍了2-甲基-5-硝基咪唑目前的应用情况。     

Selective detection of dopamine on poly(indole-5-carboxylic acid)/tyrosinase electrode

We report here on a simple tyrosinase (TYR) modified electrode designed through the covalent bonding of the enzyme with poly (indole-5-carboxylic acid) (PIn5COOH) conducting polymer. This electrode was applied to the amperometric detection of dopamine (DA) in the presence of ascorbic acid (AA), uric acid (UA) and their mixtures, in the concentration range and ratios similar to those found in blood serum. Our experiments demonstrate that the presence of these interferents (AA, UA) does not affect the selectivity of such electrode towards dopamine with linear concentration dependence in the range of 0.5–20 μM, depending on the experimental conditions, however its sensitivity depends on the type and amount of interferent present. The lower limit of detection of DA in the presence of high AA (1000 fold) or UA (500 fold) concentration was found to be 0.1–0.5 μM. The sensitivity for DA detection is 6.2 A/M cm² with UA and 2.3 A/M cm² with AA present as interfering agents. For both interferents present in the ratio 12.5:1 (AA:UA), the sensitivity drops to the value of ca. 1.3 A/M cm². The Michaelis–Menten (K_M) constant and I_max values were evaluated, showing improved electrode sensitivity towards dopamine as judged from the decrease of the Michaelis–Menten constant.     

Pt-ZSM-5/Pd-ZSM-5催化剂对正丁烷异构化反应性能的影响

采用贵金属Pt、Pd为活性组分,HZSM-5沸石为载体,制备正丁烷异构化催化剂,在加压连续微反-色谱装置上对催化剂的反应性能进行考察。结果表明,负载Pt的贵金属催化剂在350℃具有较好的活性和选择性,在该温度下,HZSM-5沸石负载质量分数0.3%的Pt时,异丁烷选择性为40.0%,在相同温度下负载质量分数0.3%Pd时,异丁烷选择性为32.9%。     

基于Li2O-TiO2-P2O5体系玻璃/微晶玻璃电解质的研究进展

近年来人们对具有NASICON结构的LiTi2(PO4)3作为快离子导体进行了深入的研究,一些研究者以Li2O-TiO2-P2O5为体系通过改变其氧化物配比或掺杂等方法将其制成玻璃或微晶玻璃以提高其离子导电率等性能。本文介绍了以Li2O-TiO2-P2O5体系为基础进行掺杂Al2O3以及其他氧化物做成玻璃或微晶玻璃的一些方法、离子传导率等性能对比。     

5-溴嘧啶衍生物的合成研究

以5-溴-2-氯嘧啶为原料,与各种酚发生取代反应,得到系列5-溴-2-取代氧基嘧啶类化合物。研究了取代基效应（包括电性效应、立体效应及取代基位置）对反应收率的影响,结果表明：取代基的空间位阻对反应收率影响很大。该工艺反应条件温和、反应操作简便、易于实施。