Stereoselective [2 + 2] photodimerization: a viable strategy for the synthesis of enantiopure cyclobutane derivatives.

The [2 + 2] photodimerization of cinnamic acid derivatives to afford enantiopure cyclobutanes has been investigated. The use of a chiral auxiliary represents a convenient and straightforward method to exert enantiocontrol on the reaction. By exploiting Evans oxazolidinones, the stereoselective light-driven cyclisation affords a functionalised cyclobutane ring with up to 99% enantiocontrol after removing the chiral auxiliary. In-flow experiments allowed us to improve further the efficiency of the methodology, leading to high conversion and excellent enantioselectivity.

Tisochrysis lutea F&M-M36 Mitigates Risk Factors of Metabolic Syndrome and Promotes Visceral Fat Browning through ß3-Adrenergic Receptor/UCP1 Signaling.

Pre-metabolic syndrome (pre-MetS) may represent the best transition phase to start treatments aimed at reducing cardiometabolic risk factors of MetS. In this study, we investigated the effects of the marine microalga Tisochrysis lutea F&M-M36 (T. lutea) on cardiometabolic components of pre-MetS and its underlying mechanisms. Rats were fed a standard (5% fat) or a high-fat diet (20% fat) supplemented or not with 5% of T. lutea or fenofibrate (100 mg/Kg) for 3 months. Like fenofibrate, T. lutea decreased blood triglycerides (p < 0.01) and glucose levels (p < 0.01), increased fecal lipid excretion (p < 0.05) and adiponectin (p < 0.001) without affecting weight gain. Unlike fenofibrate, T. lutea did not increase liver weight and steatosis, reduced renal fat (p < 0.05), diastolic (p < 0.05) and mean arterial pressure (p < 0.05). In visceral adipose tissue (VAT), T. lutea, but not fenofibrate, increased the ß3-adrenergic receptor (ß3ADR) (p < 0.05) and Uncoupling protein 1 (UCP-1) (p < 0.001) while both induced glucagon-like peptide-1 receptor (GLP1R) protein expression (p < 0.001) and decreased interleukin (IL)-6 and IL-1ß gene expression (p < 0.05). Pathway analysis on VAT whole-gene expression profiles showed that T. lutea up-regulated energy-metabolism-related genes and down-regulated inflammatory and autophagy pathways. The multitarget activity of T. lutea suggests that this microalga could be useful in mitigating risk factors of MetS.

Thyroid Homeostasis: An Intricate Network of Production, Transport, Metabolism and Receptors Interaction.

Correct thyroid function is regarded essential for maintaining the growth, differentiation and survival of most mammalian cells at homeostatic conditions [...].

Redox Properties of 3-Iodothyronamine (T1AM) and 3-Iodothyroacetic Acid (TA1).

3-iodothyronamine (T1AM) and 3-iodothyroacetic acid (TA1) are thyroid-hormone-related compounds endowed with pharmacological activity through mechanisms that remain elusive. Some evidence suggests that they may have redox features. We assessed the chemical activity of T1AM and TA1 at pro-oxidant conditions. Further, in the cell model consisting of brown adipocytes (BAs) differentiated for 6 days in the absence (M cells) or in the presence of 20 nM T1AM (M + T1AM cells), characterized by pro-oxidant metabolism, or TA1 (M + TA1 cells), we investigated the expression/activity levels of pro- and anti-oxidant proteins, including UCP-1, sirtuin-1 (SIRT1), mitochondrial monoamine (MAO-A and MAO-B), semicarbazide-sensitive amine oxidase (SSAO), and reactive oxygen species (ROS)-dependent lipoperoxidation. T1AM and TA1 showed in-vitro antioxidant and superoxide scavenging properties, while only TA1 acted as a hydroxyl radical scavenger. M + T1AM cells showed higher lipoperoxidation levels and reduced SIRT1 expression and activity, similar MAO-A, but higher MAO-B activity in terms of M cells. Instead, the M + TA1 cells exhibited increased levels of SIRT1 protein and activity and significantly lower UCP-1, MAO-A, MAO-B, and SSAO in comparison with the M cells, and did not show signs of lipoperoxidation. Our results suggest that SIRT1 is the mediator of T1AM and TA1 pro-or anti-oxidant effects as a result of ROS intracellular levels, including the hydroxyl radical. Here, we provide evidence indicating that T1AM and TA1 administration impacts on the redox status of a biological system, a feature that indicates the novel mechanism of action of these two thyroid-hormone-related compounds.

Electrochemical Organic Synthesis of Electron-Rich Biaryl Scaffolds: An Update.

Biaryl scaffolds are widely spread in biologically important natural products, in numerous therapeutic agents, but they are also considered a privileged class of ligands and (organo)catalysts; therefore, the development of efficient alternative methodologies to prepare such compounds is always attracting much attention. The present review discusses the organic electrosynthesis of biaryls starting from phenols, anilines, naphthols, and naphthylamines. The most significant examples of the works reported in the last decade are presented and classified according to the single class of molecules: after the introduction, the first three sections relate to the reactions of phenols, naphthols, and anilines, respectively; the other two sections refer to cross-coupling and miscellaneous reactions.

Angiotensin-II Drives Human Satellite Cells Toward Hypertrophy and Myofibroblast Trans-Differentiation by Two Independent Pathways.

Skeletal muscle regeneration is ensured by satellite cells (SC), which upon activation undergo self-renewal and myogenesis. The correct sequence of healing events may be offset by inflammatory and/or fibrotic factors able to promote fibrosis and consequent muscle wasting. Angiotensin-II (Ang) is an effector peptide of the renin angiotensin system (RAS), of which the direct role in human SCs (hSCs) is still controversial. Based on the hypertrophic and fibrogenic effects of Ang via transient receptor potential canonical (TRPC) channels in cardiac and renal tissues, we hypothesized a similar axis in hSCs. Toward this aim, we demonstrated that hSCs respond to acute Ang stimulation, dose-dependently enhancing p-mTOR, p-AKT, p-ERK1/2 and p-P38. Additionally, sub-acute Ang conditioning increased cell size and promoted trans-differentiation into myofibroblasts. To provide a mechanistic hypothesis on TRPC channel involvement in the processes, we proved that TRPC channels mediate a basal calcium entry into hSCs that is stimulated by acute Ang and strongly amplified by sub-chronic Ang conditioning. Altogether, these findings demonstrate that Ang induces a fate shift of hSCs into myofibroblasts and provide a basis to support a benefit of RAS and TRPC channel blockade to oppose muscle fibrosis.

Evaluation of In-Batch and In-Flow Synthetic Strategies towards the Stereoselective Synthesis of a Fluorinated Analogue of Retro-Thiorphan.

A stereoselective synthetic strategy for the preparation of trifluoromethylamine mimics of retro-thiorphan, involving a diastereoselective, metal-free catalytic step, has been studied in batch and afforded the target molecule in good yields and high diastereoselectivity. A crucial point of the synthetic sequence was the catalytic reduction of a fluorinated enamine with trichlorosilane as reducing agent in the presence of a chiral Lewis base. The absolute configuration of the key intermediate was unambiguously assigned by X-ray analysis. The synthesis was also investigated exploiting continuous flow reactions; that is, an advanced intermediate of the target molecule was synthesized in only two in-flow synthetic modules, avoiding isolation and purifications of intermediates, leading to the isolation of the target chiral fluorinated amine in up to an 87:13 diastereoisomeric ratio.

The impact of scopolamine pretreatment on 3-iodothyronamine (T1AM) effects on memory and pain in mice.

We previously demonstrated that 3-iodothyronamine (T1AM), a by-product of thyroid hormone metabolism, pharmacologically administered to mice acutely stimulated learning and memory acquisition and provided hyperalgesia with a mechanism which remains to be defined. We now aimed to investigate whether the T1AM effect on memory and pain was maintained in mice pre-treated with scopolamine, a non-selective muscarinic antagonist expected to induce amnesia and, possibly, hyperalgesia. Mice were pre-treated with scopolamine and, after 20min, injected intracerebroventricularly (i.c.v.) with T1AM (0.13, 0.4, 1.32µg/kg). 15min after T1AM injection, the mice learning capacity or their pain threshold were evaluated by the light/dark box and by the hot plate test (51.5°C) respectively. Experiments in the light/dark box were repeated in mice receiving clorgyline (2.5mg/kg, i.p.), a monoamine oxidase (MAO) inhibitor administered 10min before scopolamine (0.3mg/kg). Our results demonstrated that 0.3mg/kg scopolamine induced amnesia without modifying the murine pain threshold. T1AM fully reversed scopolamine-induced amnesia and produced hyperalgesia at a dose as low as 0.13µg/kg. The T1AM anti-amnestic effect was lost in mice pre-treated with clorgyline. We report that the removal of muscarinic signalling increases T1AM pro learning and hyperalgesic effectiveness suggesting T1AM as a potential treatment as a "pro-drug" for memory dysfunction in neurodegenerative diseases.

A stereoselective, catalytic strategy for the in-flow synthesis of advanced precursors of rasagiline and tamsulosin.

The diastereoselective, trichlorosilane-mediate reduction of imines, bearing different and removable chiral auxiliaries, in combination either with achiral bases or catalytic amounts of chiral Lewis bases, was investigated to afford immediate precursors of chiral APIs (Active Pharmaceutical Ingredients). The carbon-nitrogen double bond reduction was successfully performed in batch and in flow mode, in high yields and almost complete stereocontrol. By this metal-free approach, the formal synthesis of rasagiline and tamsulosin was successfully accomplished in micro(meso) flow reactors, under continuous flow conditions. The results of these explorative studies represent a new, important step towards the development of automated processes for the preparation of enantiopure biologically active compounds.

Square-edge intraocular lenses and epithelial lens cell proliferation: implications on posterior capsule opacification in an in vitro model.

BACKGROUND: To evaluate lens epithelial cell (LEC) proliferation with two different designs (one-piece or three-piece) of hydrophobic acrylic IOLs with 360° square optic edge using an in vitro culture model of posterior capsule opacification (PCO). METHODS: This experimental study was conducted at the Department of NEUROFARBA, Section of Pharmacology, University of Florence, Italy. Human LECs were seeded and cultured in transwell cell culture inserts coated with a type-IV collagen membrane on which an IOL (one-piece Tecnis-1 or three-piece AR40E, Abbott Medical Optics Inc.) had been previously placed. As control, cells were plated on the insert membrane without an IOL. At day six (cells confluent in controls) IOLs were removed and cell counting, viability and cell density under and outside the IOLs were evaluated. RESULTS: No statistically significant difference in the number of cells (p>0.05) between inserts with the one-piece and three-piece IOLs was found. Cell density in the area under each IOL was significantly lower than in the area outside of it (p<0.05), or in the control insert. (p<0.05). Cell density under the single-piece IOL was not significantly different from that under the three-piece IOL (p>0.05). CONCLUSIONS: A 360° sharp-edge played a crucial role in avoiding LEC migration under the IOL and preventing the formation of PCO after cataract surgery. Long term clinical evaluation is necessary to estimate functional results.

Pharmacological perspectives in sarcopenia: a potential role for renin-angiotensin system blockers?

Sarcopenia represents a major health problem highly prevalent in elderly and age-related chronic diseases. Current pharmacological strategies available to prevent and reverse sarcopenia are largely unsatisfactory thus raising the need to identify novel targets for pharmacological intervention and possibly more effective and safe drugs. This review highlights the current knowledge of the potential benefits of renin-angiotensin system blockade in sarcopenia and discuss the main mechanisms underlying the effects.

Long-term treatment with Sitagliptin, a dipeptidyl peptidase-4 inhibitor, reduces colon carcinogenesis and reactive oxygen species in 1,2-dimethylhydrazine-induced rats.

Type 2 diabetes mellitus (T2DM) and insulin resistance (IR) increase colon cancer risk. Antidiabetic drugs stabilizing incretin hormones, such as inhibitors of dipeptidyl peptidase-4 activity (DPP4i), may affect colon carcinogenesis; however, the data remain controversial. Therefore, the authors studied whether long-term administration of the DPP4i Sitagliptin (SITA) affects 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis. Male F344 rats fed a high-fat (HF) diet promoting colon carcinogenesis and IR, were induced with DMH (100 mg/kg × 2 times). One week later, the animals were allocated to two groups: one continuing with HF diet (controls; n = 8) and one receiving SITA (n = 8) mixed in the diet (260 ppm). Body weight, food consumption and glycemia were not affected by SITA. Fifteen weeks after DMH, the number of the precancerous lesions mucin-depleted foci (MDF) was significantly lower in rats treated with SITA [MDF/colon: 9.5 ± 0.9 and 6.4 ± 0.9 in controls (n = 8) and SITA groups (n = 8), respectively; means ± SE, p < 0.05]. Reactive oxygen species in the blood were also significantly lower in the SITA group [6.75 ± 0.69 and 5.63 ± 0.75 (H2 O2 in mM) in controls (n = 5) and SITA (n = 6), respectively; means ± SE, p < 0.05]. Rats treated with SITA had a lower DPP4 activity in the intestine but not in the plasma. Intestine growth morphometric parameters and colon proliferation, as proliferating cell nuclear antigen expression, were not affected by SITA. In conclusion, the results suggest a protective effect of DPP4i against colon carcinogenesis that could be exploited in chemoprevention trials.

Enantioselective reduction of ketoimines promoted by easily available (S)-proline derivatives.

The behavior of readily synthesized and even commercially available (S)-proline derivatives, was studied in the trichlorosilane-mediated reduction of ketoimines. A small library of structurally and electronically modified chiral Lewis bases was considered; such compounds were shown to promote the enantioselective reduction of different substrates in good chemical yields. In the HSiCl3 addition to the model substrate N-phenylacetophenone imine, the organocatalyst of choice led to the formation of the corresponding amine with good stereoselectivity, up to 75% ee. Theoretical studies were also performed in order to elucidate the origin of the stereoselection.

The protective effect of losartan in the nephropathy of the diabetic rat includes the control of monoamine oxidase type A activity.

Monoamine oxidase activity (MAO-A and B) levels, as intracellular source of reactive oxygen species, might increase in diabetic nephropathy (DN) contributing to reduce dopamine levels and to unbalance kidney redox state. We explored the hypothesis that beneficial effects of losartan, an angiotensin-II type 1 receptor (AT1) blocker, in DN included the control of MAO activity levels. In kidneys of normoglycemic and diabetic, streptozotocin-injected (55 mg/kg) rats, treated or untreated with losartan, an AT1 antagonist (20mg/kg/day in the drinking water), we investigated MAO activity radiochemically and antioxidant enzymes including catalase, aldehyde dehydrogenase and superoxide dysmuthase spectrophotometrically. In addition, we also evaluated malondialdehyde and carbonylated protein levels spectrophotometrically as indexes of oxidative attack to lipids and proteins. Diabetic rats showed signs of nephropathy, including renal hypertrophy, proteinuria, high acethylglucosaminidase and γ-glutamyltranspeptidase urinary levels. In diabetic kidneys, MAO-A and catalase activities as well as malondialdehyde levels, were found significantly higher than in normoglycemic ones. Interestingly, in diabetic kidneys, MAO-A activity correlated not only with catalase but also with γ-glutamyltranspeptidase urinary levels. Our results indicate that the control of MAO-A activity is to be included amongst the mechanisms of protection afforded by losartan in DN. In fact, the prevention of MAO-A raise might increase dopamine availability and, as suggested by the correlation with γ-GGT, reduce oxidative attack to tubular cells.

The effect of losartan treatment on the response of diabetic cardiomyocytes to ATP depletion.

The present work aimed to investigate the effect of losartan treatment of healthy and diabetic rats on cardiomyocyte response to ATP depletion. Cells were isolated from normoglycemic (N) and streptozotocin-injected (55 mg/kg) rats (D) treated or not treated with losartan (20 mg/kg/day in the drinking water; NL and DL, respectively) for 3 weeks. In each group of cells, enzyme activities such as glucose-6-phosphate (G6PDH) and glycerol-3-phosphate dehydrogenases (G3PDH), lactate/pyruvate, glycogen levels and citrate synthase were measured as an index of glycolytic dysregulation and mitochondrial mass, respectively. Cells were then challenged with NaCN (2 mM) in glucose-free Tyrode solution (metabolic intoxication, MI), a protocol to study ischemia at cell level. Under these conditions, the time to contractile failure up to rigor-type hyper-contracture in field-stimulated cells and K(ATP) current activation by patch-clamp recordings were measured. In comparison with N and NL, D cells presented higher G6PDH and cytoplasmic G3PDH activities, lactate/pyruvate, glycogen content but similar levels of citrate synthase, and decay time of contraction. When subjected to MI, D cells showed delayed activation of the K(ATP) current (25.7±7.1 min; p<0.001 vs. N and NL), increased time to contractile failure and rigor-type hyper-contracture (p<0.001 vs. N and NL). In cells from DL rats both functional (time to rigor and to K(ATP) current activation) and metabolic parameters, approached values similar to those measured in N and NL cells. These results demonstrate that diabetic cardiomyocytes from rats treated with losartan, maintain the capacity to respond promptly to ATP depletion reaching contractile failure, rigor-type hypercontracture and K(ATP) opening with a similar timing of N cells.

Triclorosilane-mediated stereoselective synthesis of ß-amino esters and their conversion to highly enantiomerically enriched ß-lactams.

A highly stereoselective trichlorosilane-mediated reduction of N-benzyl enamines was developed; the combination of a low cost, easy to make metal-free catalyst and an inexpensive chiral auxiliary allowed to perform the reaction on substrates with different structural features often with total control of the stereoselectivity. By easy deprotection through hydrogenolysis followed by conversion of ß-aminoester to 2-azetidinones, the synthesis of enantiomerically pure ß-lactams (>98% e.e.) was successfully accomplished.

Novel carbohydrate-based bifunctional organocatalysts for nucleophilic addition to nitroolefins and imines.

Glucosamine has been selected as a cheap and readily available chiral scaffold for the synthesis of a series of novel enantiomerically pure bifunctional organocatalysts bearing a tertiary amino group in proximity to a (thio)urea group. The catalytic behaviour of these compounds, both as neutral and N-protonated species, was investigated using the addition of acetylacetone to ß-nitrostyrene as a model reaction. Under optimized experimental conditions, chemical yields up to 93% and enantioselectivities up to 89% were obtained. Semiempirical (AM1) computational studies allowed to find a theoretical rationale for the chemical and stereochemical behaviour of the catalyst of choice. These catalysts were also preliminarily investigated as promoters in the addition of diethyl malonate to the N-Boc imine of benzaldehyde, affording the product in up to 81% ee.

The 3-iodothyronamine (T1AM) and the 3-iodothyroacetic acid (TA1) indicate a novel connection with the histamine system for neuroprotection.

The 3-iodothyronamine (T1AM) and 3-iodothryoacetic acid (TA1), are endogenous occurring compounds structurally related with thyroid hormones (THs, the pro-hormone T4 and the active hormone T3) initially proposed as possible mediators of the rapid effects of T3. However, after years from their identification, the physio-pathological meaning of T1AM and TA1 tissue levels remains an unsolved issue while pharmacological evidence indicates both compounds promote in rodents central and peripheral effects with mechanisms which remain mostly elusive. Pharmacodynamics of T1AM includes the recognition of G-coupled receptors, ion channels but also biotransformation into an active metabolite, i.e. the TA1. Furthermore, long term T1AM treatment associates with post-translational modifications of cell proteins. Such array of signaling may represent an added value, rather than a limit, equipping T1AM to play different functions depending on local expression of targets and enzymes involved in its biotransformation. Up to date, no information regarding TA1 mechanistic is available. We here review some of the main findings describing effects of T1AM (and TA1) which suggest these compounds interplay with the histaminergic system. These data reveal T1AM and TA1 are part of a network of signals involved in neuronal plasticity including neuroprotection and suggest T1AM and TA1 as lead compounds for a novel class of atypical psychoactive drugs.

3-Iodothyronamine Affects Thermogenic Substrates' Mobilization in Brown Adipocytes.

We investigated the effect of 3-iodothyronamine (T1AM) on thermogenic substrates in brown adipocytes (BAs). BAs isolated from the stromal fraction of rat brown adipose tissue were exposed to an adipogenic medium containing insulin in the absence (M) or in the presence of 20 nM T1AM (M+T1AM) for 6 days. At the end of the treatment, the expression of p-PKA/PKA, p-AKT/AKT, p-AMPK/AMPK, p-CREB/CREB, p-P38/P38, type 1 and 3 beta adrenergic receptors (ß1-ß3AR), GLUT4, type 2 deiodinase (DIO2), and uncoupling protein 1 (UCP-1) were evaluated. The effects of cell conditioning with T1AM on fatty acid mobilization (basal and adrenergic-mediated), glucose uptake (basal and insulin-mediated), and ATP cell content were also analyzed in both cell populations. When compared to cells not exposed, M+T1AM cells showed increased p-PKA/PKA, p-AKT/AKT, p-CREB/CREB, p-P38/P38, and p-AMPK/AMPK, downregulation of DIO2 and ß1AR, and upregulation of glycosylated ß3AR, GLUT4, and adiponectin. At basal conditions, glycerol release was higher for M+T1AM cells than M cells, without any significant differences in basal glucose uptake. Notably, in M+T1AM cells, adrenergic agonists failed to activate PKA and lipolysis and to increase ATP level, but the glucose uptake in response to insulin exposure was more pronounced than in M cells. In conclusion, our results suggest that BAs conditioning with T1AM promote a catabolic condition promising to fight obesity and insulin resistance.

Effect of structural modifications of ganglioside GM2 on intra-molecular carbohydrate-to-carbohydrate interaction and enzymatic susceptibility.

The effect of inter-molecular carbohydrate-to-carbohydrate interaction on basic cell biological processes has been well documented and appreciated. In contrast, very little is known about the intra-molecular carbohydrate-to-carbohydrate interaction. The presence of an interaction between the GalNAc and the Neu5Ac in GM2 detected by NMR spectroscopy represents a well-defined intra-molecular carbohydrate-to-carbohydrate interaction. This intriguing interaction is responsible for the GM2-epitope, GalNAcbeta1-->4(Neu5Acalpha2-->3)Gal-, to exhibit a rigid and compact conformation. We hypothesized that this compact conformation may be the cause for both the GalNAc and the Neu5Ac in GM2 to be refractory to enzymatic hydrolysis and the GM2 activator protein is able to interact with the compact trisaccharide GM2-epitope, rendering the GalNAc and the Neu5Ac accessible to beta-hexosaminidase A and sialidase. We have used a series of structurally modified GM2 to study the effect of modifications of sugar chains on the conformation and enzymatic susceptibility of this ganglioside. Our hypothesis was borne out by the fact that when the GalNAcbeta1-->4Gal linkage in GM2 was converted to the GalNAcbeta1-->6Gal, both the GalNAc and the Neu5Ac became susceptible to beta-hexosaminidase A and sialidase, respectively, without GM2 activator protein. We hope our work will engender interest in identifying other intra-molecular carbohydrate-to-carbohydrate interactions in glycoconjugates.