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Imidazoline derivatives with different exocyclic substituents were simply prepared from common starting materials. The procedures were carried out in an eco-friendly manner. The antioxidant activity of these derivatives was explored by different experimental assays, such as ABTS.+ and DPPH. scavenging assay, as well as reducing power assay. The structural differences are discussed in terms of the results. Sulfur analogs showed higher antioxidant activity than their oxygenated counterparts. The same tendency was observed in microbiological studies, in which the same imidazoline compounds were assayed for light-mediated activity against of Staphylococcus aureus and Escherichia coli strains. A light-enhanced activity was observed for almost all the sulfated imidazolines after exposure to UV-A (400-320 nm) light. Fil: Faillace, Martín Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Silva, Ana Paula. Universidade Federal do Piaui; Brasil Fil: Alves Borges Leal, Antonio Linkoln. Universidade Federal do Piaui; Brasil Fil: Muratori da Costa, Luciana. Universidade Federal do Piaui; Brasil Fil: Barreto, Humberto Medeiros. Universidade Federal do Piaui; Brasil Fil: Peláez, Walter José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina

Acute kidney injury (AKI) is a frequent and serious complication of sepsis; however, there are currently no effective therapies. Inflammation and oxidative stress are the major mechanisms implicated in lipopolysaccharide (LPS)-induced AKI. Dexmedetomidine (DEX) has been reported to have remarkable anti-inflammatory and antioxidant effects. Here, we examined the renoprotective effects of DEX and potential underlying mechanisms in rats with LPS-induced AKI. We analyzed renal function and structure; serum inflammatory cytokine; renal oxidant and antioxidant levels; and renal expression of glycogen synthase kinase-3β (GSK-3β)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway-related proteins in rats 4 hr after administration of LPS. Pretreatment with DEX improved renal function and significantly reduced the levels of inflammatory cytokines and oxidative stress markers. Treatment with DEX and the GSK-3β inhibitor SB216367 promoted phosphorylation of GSK-3β, induced Nrf2 nuclear translocation, and increased transcription of the Nrf2 target genes heme oxygenase-1 and NAD(P)H quinone oxidoreductase-1, primarily in renal tubules. Alpha-2-adrenergic receptor (α2-AR) antagonist atipamezole and imidazoline I 2 receptor (I 2 R) antagonist idazoxan reversed the effects of DEX. These results suggest that the renoprotective effects of DEX are mediated via α2-AR and I 2 R-dependent pathways that reduce inflammation and oxidative stress through GSK-3β/Nrf2 signaling.

Background Locomotor sensitization to repeated ethanol (EtOH) administration is proposed to play a role in early and recurring steps of addiction. The present study was designed to examine the effect of agmatine on EtOH-induced locomotor sensitization in mice. Methods Mice received daily single intraperitoneal injection of EtOH (2.5 g/kg, 20 v/v) for 7 consecutive days. Following a 3-day EtOH-free phase, the mice were challenged with EtOH on day 11 with a single injection of EtOH. Agmatine (10 to 40 μg/mouse), endogenous agmatine enhancers (l-arginine [80 μg/mouse], arcaine [50 μg/mouse], aminoguanidine [25 μg/mouse]), and imidazoline receptor agonist/antagonists were injected (intracerebroventricular [i.c.v.]) either daily before the injection of EtOH during the 7-day development phase or on days 8, 9, and 10 (EtOH-free phase). The horizontal locomotor activity was determined on days 1, 3, 5, 7, and 11. Results Agmatine (20 to 40 μg/mouse) administration for 7 days (development phase) significantly attenuated the locomotor sensitization response of EtOH challenge on day 11. Further, the agmatine administered only during EtOH-free period (days 8, 9, and 10) also inhibited the enhanced locomotor activity on the 11th day to EtOH challenge as compared to control mice indicating blockade of expression of sensitization. Daily treatment (i.c.v.) with endogenous agmatine enhancers like l-arginine (80 μg/mouse) or arcaine (50 μg/mouse) and aminoguanidine (25 μg/mouse) restrained the development as well as expression of sensitization to EtOH. Imidazoline I1 receptor agonist, moxonidine, and I2 agonist, 2-BFI, not only decreased the development and expression of locomotor sensitization but also potentiated the effect of agmatine when employed in combination. Importantly, I1 receptor antagonist, efaroxan, and I2 antagonist, idazoxan, blocked the effect of agmatine, revealing the involvement of imidazoline receptors in agmatine-mediated inhibition of EtOH sensitization. Conclusions Inhibition of EtOH sensitization by agmatine is mediated through imidazoline receptors and project agmatine and imidazoline agents in the pharmacotherapy of alcohol addiction.

Background and Purpose: Activation of type 2 imidazoline receptors has been shown to exhibit neuroprotective properties including anti‐apoptotic and anti‐inflammatory effects, suggesting a potential therapeutic value in Alzheimer's disease (AD). Here, we explored the effects of the imidazoline‐2 ligand BU224 in a model of amyloidosis. Experimental Approach: Six‐month‐old female transgenic 5XFAD and wild‐type (WT) mice were treated intraperitoneally with 5‐mg·kg−1 BU224 or vehicle twice a day for 10 days. Behavioural tests were performed for cognitive functions and neuropathological changes were investigated by immunohistochemistry, Western blot, elisa and qPCR. Effects of BU224 on amyloid precursor protein (APP) processing, spine density and calcium imaging were analysed in brain organotypic cultures and N2a cells. Key Results: BU224 treatment attenuated spatial and perirhinal cortex‐dependent recognition memory deficits in 5XFAD mice. Fear‐conditioning testing revealed that BU224 also improved both associative learning and hippocampal‐ and amygdala‐dependent memory in transgenic but not in WT mice. In the brain, BU224 reduced levels of the microglial marker Iba1 and pro‐inflammatory cytokines IL‐1β and TNF‐α and increased the expression of astrocytic marker GFAP in 5XFAD mice. These beneficial effects were not associated with changes in amyloid pathology, neuronal apoptosis, mitochondrial density, oxidative stress or autophagy markers. Interestingly, ex vivo and in vitro studies suggested that BU224 treatment increased the size of dendritic spines and induced a threefold reduction in amyloid‐β (Aβ)‐induced functional changes in NMDA receptors. Conclusion and Implications: Sub‐chronic treatment with BU224 restores memory and reduces inflammation in transgenic AD mice, at stages when animals display severe pathology.

Background and purpose Although the antinociceptive efficacies of imidazoline I2 receptor agonists have been established, the exact post-receptor mechanisms remain unknown. This study tested the hypothesis that monoaminergic transmission is critical for I2 receptor agonist-induced antinociception. Experimental approach von Frey filaments were used to assess antinociceptive effects of two I2 receptor agonists, 2-BFI and CR4056 on chronic constriction injury (CCI)-induced neuropathic pain or complete Freund's adjuvant (CFA)-induced inflammatory pain in rats. Rectal temperature was measured to assess hypothermic effects of 2-BFI. A two-lever drug discrimination paradigm in which rats were trained to discriminate 5.6 mg·kg-1 2-BFI (i.p.) from its vehicle was used to examine the discriminative stimulus effects of 2-BFI. In each experiment, pharmacological mechanisms were investigated by combining 2-BFI or CR4056 with various pharmacological manipulations of the monoaminergic system including selective reuptake inhibition, monoamine depletion and monoamine receptor antagonism. Key results In the CCI model, selective reuptake inhibitors of 5-HT (fluoxetine) or noradrenaline (desipramine), but not dopamine (GBR12909), enhanced 2-BFI-induced antinociception. Selective depletion of 5-HT or noradrenaline almost abolished 2-BFI-induced antinociception. 5-HT1A , 5-HT2A and α1 -adrenoceptor antagonists, but not other monoaminergic antagonists, attenuated 2-BFI and CR4056-induced antinociception in CCI and/or CFA models. However, none of these monoamine receptor antagonists significantly altered 2-BFI-induced hypothermia or discriminative stimulus effects. Conclusions and implications Antinociception induced by I2 receptor agonists was mediated by serotonergic and noradrenergic mechanisms with 5-HT1A , 5-HT2A and α1 -adrenoceptor being particularly important. In contrast, the hypothermic and discriminative stimulus effects of I2 receptor agonists were mediated by distinct, independent mechanisms.

Morin is a flavonoid contained in guava that is known to reduce hyperglycemia in diabetes. Insulin secretion has been demonstrated to increase following the administration of morin. The present study is designed to investigate the potential mechanism(s) of morin-induced insulin secretion in the MIN6 cell line. First, we identified that morin induced a dose-dependent increase in insulin secretion and intracellular calcium content in MIN6 cells. Morin potentiated glucose-stimulated insulin secretion (GSIS). Additionally, we used siRNA for the ablation of imidazoline receptor protein (NISCH) expression in MIN6 cells. Interestingly, the effects of increased insulin secretion by morin and canavanine were markedly reduced in Si-NISCH cells. Moreover, we used KU14R to block imidazoline I3 receptor (I-3R) that is known to enhance insulin release from the pancreatic β-cells. Without influence on the basal insulin secretion, KU14R dose-dependently inhibited the increased insulin secretion induced by morin or efaroxan in MIN6 cells. Additionally, effects of increased insulin secretion by morin or efaroxan were reduced by diazoxide at the dose sufficient to open KATP channels and attenuated by nifedipine at the dose used to inhibit L-type calcium channels. Otherwise, phospholipase C (PLC) is introduced to couple with imidazoline receptor (I-R). The PLC inhibitor dose-dependently inhibited the effects of morin in MIN6 cells. Similar blockade was also observed in protein kinase C (PKC) inhibitor-treated cells. Taken together, we found that morin increases insulin secretion via the activation of I-R in pancreatic cells. Therefore, morin would be useful to develop in the research and treatment of diabetic disorders.

A series of 1-[(imidazolidin-2-yl)imino]-1H-indole analogues of hypotensive α2-AR agonists 1-[(imidazolidin-2-yl)imino]-1H-indazoles, was synthesized and tested in vitro for their activities at α1- and α2-adrenoceptors as well as imidazoline I1 and I2 receptors. The most active 1-[(imidazolidin-2-yl)imino]-1H-indoles displayed high or moderate affinities for α1- and α2-adrenoceptors and substantial selectivity for α2-adrenoceptors over imidazoline-I1 binding sites. The in vivo cardiovascular properties of indole derivatives 3 revealed that substitution at C-7 position of the indole ring may result in compounds with high cardiovascular activity. Among them, 7-fluoro congener 3g showed the most pronounced hypotensive and bradycardic activities in this experiment at a dose as low as 10 μg/kg i.v. Metabolic stability of the selected compounds of type 3 were determined using both in vitro and in silico approaches. The results indicated that these compounds are not vulnerable to rapid first phase oxidative metabolism. This article is protected by copyright. All rights reserved.

Background and purpose Agmatine, a putative neurotransmitter, plays a vital role in learning and memory. Although it is considered an endogenous ligand of imidazoline receptors, agmatine exhibits high affinity for α-adrenoceptors, NOS and NMDA receptors. These substrates within the locus coeruleus (LC) are critically involved in learning and memory processes. Experimental approach The hippocampus and LC of male Wistar rat were stereotaxically cannulated for injection. Effects of agmatine, given i.p. or intra-LC, on acquisition, consolidation and retrieval of inhibitory avoidance (IA) memory were measured. The NO donor S-nitrosoglutathione, non-specific (L-NAME) and specific NOS inhibitors (L-NIL, 7-NI, L-NIO), the α2 -adrenoceptor antagonist (yohimbine) or the corresponding agonist (clonidine) were injected intra-LC before agmatine. Intra-hippocampal injections of the NMDA antagonist, MK-801 (dizocilpine), were used to modify the memory enhancing effects of agmatine, SNG and yohimbine. Expression of tyrosine hydroxylase (TH) and eNOS in the LC was assessed immunohistochemically. Key results Agmatine (intra-LC or i.p.) facilitated memory retrieval in the IA test. S-nitrosoglutathione potentiated, while L-NAME and L-NIO decreased, these effects of agmatine. L-NIL and 7-NI did not alter the effects of agmatine. Yohimbine potentiated, whereas clonidine attenuated, effects of agmatine within the LC. The effects of agmatine, S-nitrosoglutathione and yohimbine were blocked by intra-hippocampal MK-801. Agmatine increased the population of TH- and eNOS-immunoreactive elements in the LC. Conclusions and implications The facilitation of memory retrieval in the IA test by agmatine is probably mediated by interactions between eNOS, NO and noradrenergic pathways in the LC.

OBJECTIVES Alpha-2 adrenergic receptors target several behavioral functions. These receptors may connect with the brain pathways mediating sensorimotor gating system that associate with psychoses, and the literature that investigate the relationship between alpha-2 receptors and sensorimotor gating system is very limited and some results are controversial. Thus, we aimed to investigate the role of alpha-2 receptors on prepulse inhibition (PPI) of acoustic startle reflex which is a measure of sensorimotor gating. EXPERIMENTAL DESIGN Adult male Wistar rats were subjects. PPI was measured as the per cent inhibition of the startle reflex produced by a startling pulse stimulus. The average PPI levels were used in the further analyses. Clonidine (0.03-1 mg/kg), an agonist of alpha-2 receptors, idazoxan (10 mg/kg), an antagonist alpha-2 receptors, and saline were injected to rats intraperitoneally. PPI was evaluated at two different startle intensity levels (78 and 86 dB, respectively). PRINCIPAL OBSERVATIONS Treatments produced some significant changes on PPI of startle reflex at all two levels of startle intensity. While clonidine (0.06, 0.25, 0.5, and 1 mg/kg) disrupted significantly PPI, idazoxan (10 mg/kg) did not produce any significant effect on PPI. However, pretreatment with idazoxan reversed significantly clonidine-induced disruption of PPI. Neither idazoxan (10 mg/kg) nor clonidine (1 mg/kg) produces any significant change on locomotor activity in naive rats. CONCLUSION Because idazoxan and clonidine also act through imidazoline receptors, our results suggest that alpha-2 and/or imidazoline receptors are associated with PPI of acoustic startle reflex in rats. Stimulation of these receptors may cause sensorimotor gating disturbances.

Over the year, the 2-substituted imidazoline nucleus has been demonstrated to be a bioversatile structural motif. In this study, novel imidazoline derivatives, bearing a 3- and/or 4-hydroxy- or methoxy-substituted phenyl ring linked by an ethylene bridge to the position 2 of an N-benzyl- or N-phenethyl-substituted imidazoline nucleus, were prepared and studied at the D2-like receptor subtypes. Binding studies highlighted that the N-phenethylimidazolines 10–12 and 15 were selective for D4 over D2 and D3 receptors. In the functional assays the 3-methoxy-substituted derivative 12, endowed with the highest D4 affinity value, and its 3-hydroxy analogue 15 behaved as partial agonists with low intrinsic efficacy and as competitive D4 antagonists when tested in the presence of the D2-like receptor agonist quinpirole. The molecular docking analysis, performed at a homology model of human D4 receptor developed by using the X-ray crystal structure of the antagonist-bound human D3 receptor as template, was in accordance to the binding results and provided useful information for the design of novel imidazoline D4 receptor ligands based on the scaffold I.

Background and Purpose This study examined the effects of imidazoline I2 receptor agonists on the development of tolerance to and physical dependence on repeated morphine treatment in rats. Experimental Approach Two groups of rats (n = 9 per group) were trained to lever press for sucrose (10%) presentation under a fixed-ratio 10 schedule. The rate-suppressing effects of the opioid receptor ligands morphine and naltrexone and the I2 receptor agonist 2-BFI were examined weekly in rats treated with either daily morphine (20 mg·kg−1, s.c.), alone or in combination with 2-BFI (10 mg·kg−1) for 3 weeks. Changes in body weight were measured following naltrexone tests in both groups of rats. In separate experiments, the antinociceptive effects of morphine were assessed using a warm-water tail-withdrawal procedure in rats before and after daily treatments (7 days) with morphine (32 mg·kg−1, i.p.) alone or in combination with various doses of the I2 receptor agonists 2-BFI, BU224 and CR4056. Key Results Daily treatment for 3 weeks, with morphine in combination with 2-BFI produced significantly less tolerance to the rate-suppressing effects of morphine and produced a decreased sensitivity to the rate-suppressing effects of naltrexone as well as decreased naltrexone-induced weight loss, compared with morphine-alone group. Repeated treatment for 7 days with morphine produced antinociceptive tolerance, which was attenuated by co-administration with 2-BFI, BU224 or CR4056. Conclusions and Implications Imidazoline I2 receptor agonists attenuated the development of tolerance to and physical dependence on morphine, further supporting the therapeutic potential of combining I2 receptor agonists and opioids for pain treatment.

The inhibition effect of tall oil diethylenetriamine imidazoline (TOFA/DETA imidazoline) on corrosion of mild steel in CO2-saturated 3 wt% NaCl solution was investigated by electrochemical impedance spectroscopy (EIS), potentiodynamic sweep (PDS), cyclic voltammetry (CV), quartz crystal microbalance measurements (QCM), and scanning electron microscopy (SEM). TOFA/DETA imidazoline is a mixed-type corrosion inhibitor with the predominant anodic effect. The results of CV measurements indicate inhibited electrode processes in the presence of TOFA/DETA imidazoline and the absence of the rapid degradation of TOFA/DETA imidazoline in the range of mild steel corrosion potential. The corrosion rate of mild steel significantly decreased in the presence of TOFA/DETA imidazoline, while the inhibition efficiency increased up to 92%. It was found that the adsorption of studied imidazoline compound on steel surface followed both Langmuir and Temkin adsorption isotherms. The value of molecular interaction constant calculated from Temkin adsorption isotherm implied the existence of lateral repulsion between adsorbed inhibitor molecules.

Imidazoline I2 receptors (I2-IRs) are widely distributed in the brain. I2-IRs are associated with analgesia and human brain disorders, such as depression and Alzheimer’s disease (AD). Since, a high...

Summary Canavanine is a guanidinium derivative that contains the basic structure of the ligand(s) of imidazoline receptor (I-R). Canavanine has been reported to activate the imidazoline I-3 receptor (I-3R) both in vivo and in vitro. Additionally, the activation of the imidazoline I-2B receptor (I-2BR) by guanidinium derivatives may increase glucose uptake. Therefore, the effect of canavanine on the I-2BR was investigated in the present study. Glucose uptake into cultured C2C12 cells was determined using the radio-ligated tracer 2-[14C]-deoxy-glucose. The changes in 5′ AMP-activated protein kinase (AMPK) expression were also identified using Western blotting analysis. The canavanine-induced glucose uptake was inhibited in a dose-dependent manner by BU224 (0.01–1 μmol/L), which is a specific I-2BR antagonist, in the C2C12 cells. Additionally, the canavanine-stimulated AMPK phosphorylation and glucose transporter (GLUT4) expression were also sensitive to BU224 inhibition in the C2C12 cells. Moreover, both canavanine-stimulated glucose uptake and AMPK phosphorylation were attenuated by high concentrations of amiloride (1–2 μmol/L), which is another established I-2BR inhibitor, in a dose-dependent manner in C2C12 cells. Additionally, compound C abolished the canavanine-induced glucose uptake and AMPK phosphorylation at a concentration (0.1 μmol/L) sufficient to inhibit AMPK. In conclusion, these data demonstrated that canavanine has an ability to activate I-2BR through the AMPK pathway to increase glucose uptake, which indicates I-2BR as a new target for diabetic therapy.

New alkyl hydroxyethyl imidazoline salts were synthesized via a high pressure process with imidazoline and dimethyl carbonate, and their chemical structure were confirmed using mass spectral fragmentation and FTIR spectroscopic analysis. In addition, several quaternary ammonium salts with new counterions (formic acid, acetic acid and lactic acid) were also synthesized by ion exchange reaction of methyl carbonate quaternary ammoniums with the corresponding acids. These new compounds reduced the surface tension of water to a minimum value of approximately 27 mN m−1 at a concentration of 8.72 × 10−5 mol L−1. They also show efficient corrosion inhibition performances and could significantly inhibit the corrosion of mild steel in acid solutions. It was also found that the biological degradation of these imidazoline surfactants was greater than 98 % after 7 days.

The catalytic enantioselective reaction of diphenylmethylidene-protected α-aminoacetonitriles with imines has been developed. Good yields and diastereo- and enantioselectivities were observed for the reaction of various imines using chiral bis(imidazoline)/Pd catalysts. The reaction of α-aminonitriles with di-tert-butyl azodicarboxylate afforded chiral α,α-diaminonitriles in high yields with high enantioselectivities.

The amidoamines (S)-Ar1CONHCHRCH2NHAr2 [Ar1 = o-C6H4SO3H, R = Bn, iBu, iPr; Ar2 = 2,6-iPr2C6H4, 2,6-Et2C6H4, 2,4,6-Me3C6H2] cyclise to (S) 1-aryl-substituted 4,5-dihydro-1H-imidazolinium species with HC(OEt)3 in moderate-to-excellent yields on heating to 150–175 °C (nine examples, four isolated yields of 48 to >97 %). They are attained as their o-C6H4(SO3–)(CO2Et) salts. The latter are readily deprotonated to afford analytically pure (S) 1-aryl-substituted 4,5-dihydro-1H-imidazoles (imidazolines). The purification of the intermediate sulfonate salts is not always necessary, and analytically pure imidazolines are isolated by simple kugelrohr distillation (nine examples, 45–95 %) after basification. Imidazoline alkylation provides a library of (S)-N-alkylimidazolinium salts (23 examples, 74–97 %). As the initially required amidoamines are available in simple one-pot reactions, the overall approach constitutes a rather efficient approach to this useful family of chiral N-heterocyclic carbene (NHC) ligand precursors (effectively three steps from commercial N-Boc-α-amino alcohols; BOC = tert-butyloxycarbonyl).

We report herein the asymmetric coupling of flow‐generated unstabilized diazo compounds and propargylated amine derivatives, using a new pyridinebis(imidazoline) ligand, a copper catalyst and base. The reaction proceeds rapidly, generating chiral allenes in 10–20 minutes with high enantioselectivity (89–98 % de/ee), moderate yields and a wide functional group tolerance.

Background and Purpose A new imidazoline I2 receptor ligand, CR4056, is effective for chronic inflammatory pain and diabetic neuropathy. However, it is unclear whether other I2 receptor ligands have similar effects and whether antinociceptive tolerance develops with repeated treatment. Experimental Approach The Von Frey filament test was used to measure mechanical hyperalgesia and the plantar test to measure thermal hyperalgesia in rats injected with complete Freund's adjuvant (CFA) treatment or had undergone surgery to induce chronic constriction injury (CCI), models of inflammatory pain and peripheral neuropathic pain respectively. The effects of morphine and I2 receptor ligands, 2-BFI, BU224, tracizoline and CR4056, 3.2–32 mg·kg−1, i.p., on hyperalgesia or affective pain (as measured by a place escape/avoidance paradigm) were studied in separate experiments. Key Results Morphine and the I2 receptor ligands (2-BFI, BU224 and tracizoline) all dose-dependently attenuated mechanical and thermal hyperalgesia in CFA-treated rats. The anti-hyperalgesic effects of 2-BFI in CFA-treated and CCI rats were attenuated by the I2 receptor antagonist idazoxan. The combination of 2-BFI and morphine produced additive effects against mechanical hyperalgesia in CFA-treated rats. Repeated treatment (daily for 7–9 days) with 2-BFI or CR4056 did not produce antinociceptive tolerance in CFA-treated or CCI rats. Morphine and the I2 receptor ligands (2-BFI, BU224 and CR4056) were all effective at attenuating place escape/avoidance behaviour in CFA-treated rats. Conclusions and Implications Imidazoline I2 receptor ligands have antihyperalgesic effects in rat models of inflammatory and neuropathic pain and may represent a new class of pharmacotherapeutics for the management of chronic pain.

The structure of a nickel complex of imidazoline-aminophenol (IAP) prepared from IAP with Ni(OAc)2 was elucidated as cis-bis(imidazolineaminophenoxide) [Ni(IAP)2]. The [Ni(IAP)2] complex smoothly promoted catalytic asymmetric 1,4-addition of 3'-indolyl-3-oxindole to nitroethylene to provide chiral mixed 3,3'-bisindoles with high enantioselectivities. Mechanistic studies using ESI-MS analyses suggest that one IAP ligand dissociated from [Ni(IAP)2] to generate the Ni-enolate of 3'-indolyl-3-oxindole. From the optically active 3,3'-mixed indole adduct, biologically important 3'-indolyl-3-pyrrolidinoindoline was successfully synthesized in a three-step reaction sequence.

Objectives The effect of agmatine on bladder contractility and the diabetes-induced alteration of this action were studied in the rat. Methods Bladder strips were isolated from 9-week-old streptozotocin (STZ)-diabetic rats and control Wistar rats. Strips were hung in an organ bath for measurement of isometric tension and pre-contracted with either 1 µmol/L acetylcholine (ACh) or 50 mmol/L KCl. Dose-dependent relaxation of the bladder strips was studied by cumulative administration of agmatine 1–100 µmol/L into the organ bath. Effects of specific imidazoline receptor (IR) antagonists on the agmatine-induced relaxation were studied. Western blotting analysis was used to measure bladder IR, sulphonylurea receptor (SUR) and inwardly rectifying K+ channel subunit 6.2 (Kir 6.2) protein levels. Results Agmatine reduced ACh and KCl pre-contracted bladder strip tension in a dose-dependent fashion. Relaxation was significantly increased in STZ-diabetic rats. The relaxation was inhibited by BU224, a selective I2 IR antagonist; but not by efaroxan (I1 IR antagonist) or KU14R (I3 IR antagonist). Moreover, the agmatine-induced relaxation was attenuated by glibenclamide (inhibitor of KATP channel) and H-89 (inhibitor of protein kinase A), but enhanced by 3-isobutyl-1-methylxanthine (IBMX, inhibitor of cyclic AMP phosphodiesterase). Western blotting showed increased expression of bladder IR but not SUR or Kir 6.2 in the STZ-diabetic rat. Conclusion Agmatine causes rat bladder relaxation by activation of the I2 IR, which opens KATP channels through the cyclic AMP/protein kinase A pathway. Agmatine-induced bladder relaxation in STZ-diabetic rats is increased due to a higher expression of IR.

The inhibition performance of two imidazoline inhibitors, 1-(2-thioureaethyl)-2-alkyl-imidazoline (TAI) and chloride-1-(2,3-dihydroxylpropyl)-1-(2-thioureaethyl)-2-alkyl-imidazoline sodium phosphate (TAIP), for Q235 steel in saltwater saturated with CO2 was studied by using molecular dynamics simulations and quantum chemistry calculations. The conclusions were experimentally verified by weight loss, polarization curves, electrochemical impedance spectroscopy (EIS) and surface analysis techniques. The theoretical results suggest that imidazoline ring and heteroatoms are the active site and the adsorption stability weakens gradually in the order of TAIP, TAI. Experimental results show that the two inhibitors act as mixed type inhibitors and can inhibit the corrosion of Q235 in CO2 saturated saltwater solution.

This work focuses on the testing of imidazoline based corrosion inhibitor and the inhibition of carbon steel corrosion caused by carbon dioxide saturated oilfield brine solution. Electrochemical impedance spectroscopy, linear polarization, anodic and cathodic polarization (Tafel extrapolation method) measurements were carried out. In order to investigate imidazoline based corrosion inhibitor efficiency, carbon dioxide saturated oilfield brine solution without inhibitor and solution with added different concentrations of imidazoline based corrosion inhibitor were tested. Those results were compared. Influence of testing solution temperature and stirring of testing solution on the corrosion inhibitor efficiency were investigated. On the basis of obtained results it can be concluded that optimal concentration of imidazoline based corrosion inhibitor is 50 ppm for the successful and effective corrosion protection of pipelines made of carbon steel under test conditions similar to typical oilfield conditions (35°C, atmospheric pressure, stirring rate 400 min–1). Diese Arbeit befasst sich mit der Prufung von auf Imidazolin basiertem Korrosionsinhibitor und dessen Hemmung auf die Korrosion von Kohlenstoffstahl verursacht durch Olfeld-Salzwasserlosung, die mit Kohlendioxid gesattigt ist. Es wurden Messungen zur elektrochemischen Impedanzspektroskopie, die Methode der linearen Polarisation sowie anodische und kathodische Polarisationsmessungen (Tafel Extrapolationsmethode) durchgefuhrt. Um die Effizienz des auf Imidazolin basierten Korrosionsinhibitors zu untersuchen, wurde die mit Kohlendioxid gesattigte Olfeld-Salzwasserlosung ohne Inhibitor und die Losung mit unterschiedlichen Konzentrationen des Inhibitors getestet und miteinander verglichen. Auch der Einfluss der gepruften Losungstemperatur und die Bewegung der Pruflosung auf die Wirkung des Korrosionsinhibitors ist untersucht worden. Auf Grundlage der erzielten Ergebnisse kann geschlossen werden, dass die optimale Konzentration fur einen auf Imidazolin basierten Korrosionsinhibitor 50 ppm betragt, um einen erfolgreichen und effektiven Korrosionsschutz von Pipelines aus Kohlenstoffstahl unter ahnlichen Testbedingungen wie den Olfeldbedingungen (35°C, Atmospharendruck, Ruhrgeschwindigkeit 400 min–1) zu erhalten.

Get selective! Enantioselective allylation of ketimines derived from isatins by using chiral 1,3-bis(imidazolin-2-yl)benzene (Phebim)-Pd(II) complexes afforded products with good enantioselectivity (see scheme). The reaction was applied to a wide variety of ketimines. The obtained product can be converted to homoallylic amines and a spirocyclic amine without the loss of enantiopurity.

TOP class: The first efficient catalytic asymmetric coupling reaction of indoles with isatin-derived nitroalkenes was accomplished by using a complex consisting of a chiral imidazoline aminophenol ligand (1; see scheme) and Cu(OTf)(2). Biological activity of the newly formed chiral 3,3'-bisindoles was also confirmed in a Wnt signaling inhibitory assay.

In this paper, the inhibition performance of a novel dissymmetric bis-quaternary ammonium salt with an imidazoline ring and an ester group (DBAS) for Q235 steel in 2 % NaCl solution saturated with CO2 was investigated using weight loss, the polarization curve, electrochemical impedance spectroscopy methods and the quantum chemistry calculation. The results show that DBAS, which is good for the environment and have many activated centers and low ELUMO, has a high inhibition performance for Q235 steel in 2 % NaCl solution saturated with CO2. The inhibition efficiency of the studied corrosion inhibitor increased with increasing inhibitor concentrations. The inhibitor is a mixed-type inhibitor which inhibits both anodic and cathodic reactions.

The gas-phase proton affinities (PAs) for a set of molecules with vinamidine structure are considered and their basicities in acetonitrile. It is shown that introducing double bonds to the imidazoline rings at the proton attachment site resulted in decrease in PA of the parent vinamidine. The increase in PA can be obtained by inducing modifications to the imidazoline ring at the junction of two diazepinylium rings. Placing methyl and dimethylamino substituents on the perimeter of the molecule further increased their gas-phase PAs. Studied vinamidine molecules are superbases, which possess PA values in the range between 261.0 and 284.2 kcal mol–1 in the gas phase and pKa values of 24.6–31.9 units in acetonitrile. Dismembering proton attachment site by opening the two diazepinylium and imidazoline rings resulted in the largest drop in PA values, indicating its importance in constraining the positions of imino nitrogen atoms in the neutral form of the molecule. Vinamidine molecules studied here present important pieces of the ladder of highly basic organic compounds for they possess accessible vinamidine molecular framework. Copyright © 2012 John Wiley & Sons, Ltd.

The surface properties of a series of imidazoline-based dissymmetric bis-quaternary ammonium (DBA) salts with different hydrophobic chain lengths DBA-12, DBA-14 and DBA-16 were determined. The adsorption behaviors of these compounds in 1 M HCl solution and their inhibitive effect on Q235 steel (U12350) were investigated using the weight-loss method, polarization, and electrochemical impedance spectroscopy. Results indicate that the three inhibitors all showed good inhibition performance for Q235 Steel in 1 M HCl solution and were found to be mixed-type inhibitors. The adsorption behavior of the three inhibitors can fit the Langmuir isotherm equation and the values of \( \Updelta G_{\text{ads}}^{0} \) are around or lower than 40 kJ mol−1, indicating that there is a stronger chemical adsorption.

BACKGROUND AND PURPOSE Imidazoline I(2) receptors have been implicated in several CNS disorders. Although several I(2) receptor agonists have been described, no simple and sensitive in vivo bioassay is available for studying I(2) receptor ligands. This study examined I(2) receptor agonist-induced hypothermia as a functional in vivo assay of I(2) receptor agonism. EXPERIMENTAL APPROACH Different groups of rats were used to examine the effects of I(2) receptor agonists on the rectal temperature and locomotion. The pharmacological mechanisms were investigated by combining I(2) receptor ligands and different antagonists. KEY RESULTS All the selective I(2) receptor agonists examined (2-BFI, diphenyzoline, phenyzoline, CR4056, tracizoline, BU224 and S22687, 3.2-56 mg·kg(-1) , i.p.) dose-dependently and markedly decreased the rectal temperature (hypothermia) in rats, with varied duration of action. Pharmacological mechanism of the observed hypothermia was studied by combining the I(2) receptor agonists (2-BFI, BU224, tracizoline and diphenyzoline) with imidazoline I(2 ) receptor/ α(2) adrenoceptor antagonist idazoxan, selective I(1) receptor antagonist efaroxan, α(2) adrenoceptor antagonist/5-HT(1A) receptor agonist yohimbine. Idazoxan but not yohimbine or efaroxan attenuated the hypothermic effects of 2-BFI, BU224, tracizoline and diphenyzoline, supporting the I(2) receptor mechanism. In contrast, both idazoxan and yohimbine attenuated hypothermia induced by the α(2) adrenoceptor agonist clonidine. Among all the I(2) receptor agonists studied, only S22687 markedly increased the locomotor activity in rats. CONCLUSIONS AND IMPLICATIONS Imidazoline I(2) receptor agonists can produce hypothermic effects, which are primarily mediated by I(2) receptors. These data suggest that I(2) receptor agonist-induced hypothermia is a simple and sensitive in vivo assay for studying I(2) receptor ligands.

Potentiation of opioid analgesia by endothelin-A (ET(A)) receptor antagonist, BMS182874, and imidazoline receptor/α₂-adrenoceptor agonists such as clonidine and agmatine are well known. It is also known that agmatine blocks morphine hyperthermia in rats. However, the effect of agmatine on morphine or oxycodone hypothermia in mice is unknown. The present study was carried out to study the role of α₂-adrenoceptors, imidazoline, and ET(A) receptors in morphine and oxycodone hypothermia in mice. Body temperature was determined over 6 h in male Swiss Webster mice treated with morphine, oxycodone, agmatine, and combination of agmatine with morphine or oxycodone. Yohimbine, idazoxan, and BMS182874 were used to determine involvement of α₂-adrenoceptors, imidazoline, and ET(A) receptors, respectively. Morphine and oxycodone produced significant hypothermia that was not affected by α₂-adrenoceptor antagonist yohimbine, imidazoline receptor/α₂ adrenoceptor antagonist idazoxan, or ET(A) receptor antagonist, BMS182874. Agmatine did not produce hypothermia; however, it blocked oxycodone but not morphine-induced hypothermia. Agmatine-induced blockade of oxycodone hypothermia was inhibited by idazoxan and yohimbine. The blockade by idazoxan was more pronounced compared with yohimbine. Combined administration of BMS182874 and agmatine did not produce changes in body temperature in mice. However, when BMS182874 was administered along with agmatine and oxycodone, it blocked agmatine-induced reversal of oxycodone hypothermia. This is the first report demonstrating that agmatine does not affect morphine hypothermia in mice, but reverses oxycodone hypothermia. Imidazoline receptors and α₂-adrenoceptors are involved in agmatine-induced reversal of oxycodone hypothermia. Our findings also suggest that ET(A) receptors may be involved in blockade of oxycodone hypothermia by agmatine.

What's known on the subject? and What does the study add? Neurotransmitters are known to control prostate contractility. Agmatine is one of them and induces relaxation through imidazoline receptors. The paper shows that the action of agmatine is reduced in hypertensive rats, and that this change is related to the decrease of ATP-sensitive potassium channels in the prostate. The findings can increase our understanding of the possible underlying mechanism for the development of clinical benign prostatic hyperplasia. OBJECTIVES • To compare agmatine-induced prostatic relaxation in hypertensive and control rats. • To investigate the responsible mechanism(s) and the role of the ATP-sensitive potassium channel. METHODS • Prostate strips were isolated from male spontaneously hypertensive (SH) rats and normal Wistar-Kyoto (WKY) rats for measurement of isometric tension. The strips were precontracted with 1 µmol/L phenylephrine or 50 mmol/L KCl. Dose-dependent relaxation of the prostatic strips was studied by cumulative administration of agmatine, 1 to 100 µmol/L, into the organ bath. • Effects of specific antagonists on agmatine-induced relaxation were studied. • Western blotting analysis was used to measure the gene expression of the ATP-sensitive potassium channel in the rat prostate. RESULTS • Prostatic relaxation induced by agmatine was markedly reduced in SH rats compared with WKY rats. • The relaxation caused by agmatine was abolished by BU224, a selective imidazoline I2-receptor antagonist, but was not modified by efaroxan at a dose sufficient to block imidazoline I1-receptors. • The relaxation induced by diazoxide at a concentration sufficient to activate ATP-sensitive potassium channels was markedly reduced in the SH rat prostate. • Expressions of ATP-sensitive potassium channel sulphonylurea receptor and inwardly rectifying potassium channel (Kir) 6.2 subunits were both decreased in the prostate of SH rats. CONCLUSION • The decrease of agmatine-induced prostatic relaxation in SH rats is related to the change in ATP-sensitive potassium channels.

Objectives: The effect of agmatine on prostate contractility as well as the roles of imidazoline receptors and potassium channels in this action were studied using isolated Wistar rat prostate tissue. Methods: Rat prostate strips were pre-contracted with 1 µmol/L phenylephrine or 50 mmol/L KCl. The relaxation response to agmatine (1–100 µmol/L) was measured. The effects of imidazoline receptor blockers: efaroxan, BU224, KU14R; ATP-sensitive K+ channels (KATP) channel inhibitor: glibenclamide; cyclic AMP (cAMP) phosphodiesterase inhibitor: IBMX; or protein kinase A (PKA) inhibitor: H-89 on the agmatine-induced relaxation were studied. Results: Agmatine produced relaxation in prostate strips pre-contracted with phenylephrine or KCl in a dose-dependent manner. This relaxation was significantly reduced by BU224, a selective I2 imidazoline receptor (IR) blocker, but not by I1 or I3 IR blockers (efaroxan, KU14R respectively). Moreover, the agmatine-induced relaxation was attenuated by glibenclamide and H-89, but enhanced by IBMX. Conclusion: The results suggest that agmatine causes rat prostate relaxation by activation of the I2 IR, which opens KATP channels through cAMP/PKA pathway.

The density of the Imidazoline2 binding site (I2BS) has been shown to change in psychiatric conditions such as depression and addiction, along with neurodegenerative disorders such as Alzheimer's disease and Huntington's chorea. The presence of I2BS on glial cells and the possibility that they may in some way regulate glial fibrillary acidic protein has led to increased interest into the role of I2BS and I2BS ligands in conditions characterized by marked gliosis. In addition, it has been suggested that I2BS may be a marker for human glioblastomas. Therefore, the development of a positron emission tomography (PET) radioligand for the I2BS would be of major benefit in our understanding of these conditions. We now report the successful synthesis and initial pharmacological evaluation of potential PET radioligands for the I2BS as well as the tritiation and characterization of the most favorable of the series, BU99008 (6), both in vitro and ex vivo in rat. The series as a whole demonstrated excellent affinity and selectivity for the I2BS, with BU99008 (6) selected as the lead candidate to be taken forward for in vivo assessment. BU99008 (6) showed very good affinity for the I2BS (Ki of 1.4 nM; Kd = 1.3 nM), good selectivity compared with the α2-adrenoceptor (909-fold). In addition, following peripheral administration, [3H]BU99008 demonstrated a heterogenous uptake into the rat brain consistent with the known distribution of the I2BS in vivo. This, and the amenability of BU99008 (6) to radiolabeling with a positron-emitting radioisotope, indicates its potential as a PET radioligand for imaging the I2BS in vivo. Synapse, 2012. © 2012 Wiley Periodicals, Inc.

Switchable surfactants are environment-friendly compounds, which can be separated from the system or lose surface activity after completing their function during one stage of a process. In order to study switchable properties of a kind of CO2 switchable surfactant with an imidazoline group, four 2-alkyl-1-hydroxyethylimidazolines were synthesized by condensation of N-(2-hydroxyethyl)ethanediamine with dodecanoic, tetradecanoic, hexadecanoic, and octadecanoic acids. Then, the series of long-chain alkyl imidazoline compounds were reacted with dry ice to produce imidazolinium bicarbonates cationic surfactants. The critical micelle concentration (CMC) and surface tension at CMC (γcmc) measured by the Wilhelmy plate technique show that these surfactants have excellent surface activity. The changes of conductivity before and after bubbling CO2 show the conversion between imidazolines and imidazolinium bicarbonates cationic surfactants. Conductivity cycles indicated that these surfactants could be switched by CO2 reversibly and repeating this three times. However, their switchable function on the emulsification-demulsification of water-alkane was dissatisfactory due to the emulsibility of amide which was hydrolyzed from 2-alkyl-1-hydroxyethylimidazoline. Therefore, the application of these switchable surfactants needed to be studied further.

Chiral, self-supported, polytopic imidazoline–pyridine ligands were designed and synthesized for use in Cu catalysis. The tripodal imidazoline–pyridine L6-Cu(BF4)2 complex catalyzed the asymmetric p-(tert-butyl)benzoylation of meso-hydrobenzoin to give the adduct in up to 85 % ee. After completion of the asymmetric benzoylation reaction, the self-supported tripodal imidazoline–pyridine–Cu catalyst could be easily recovered as a precipitate by adding hexane, and the recovered catalyst could be reused several times while maintaining the catalyst activity and selectivity.

α,β- and α,α- Diaminoacetonitriles are highly syn-selectively and enantioselectively obtained by reaction of N-protected α-aminoacetonitriles with various imines in the presence of a chiral Pd-catalyst.