Exploring nordihydroguaretic acid (NDGA) as a plausible neurotherapeutic in the experimental paradigm of autism spectrum disorders targeting nitric oxide pathway

The present study investigates the neuro-protective ability of nordihydroguaretic acid (NDGA) in the experimental paradigm of autism spectrum disorders (ASD) and further decipher the nitric oxide pathway's role in its proposed action. An intracerebroventricular infusion of 4 μl of 1 M PPA was given in the lateral ventricle's anterior region to induce autism-like phenotype in male rats. Oral administration of NDGA (5, 10 & 15 mg/kg) was initiated from the 3^rd day lasting till the 28th day. L-NAME (50 mg/kg) and L-Arginine (800 mg/kg) were also given individually and combined to explore NDGA's ability to act via the nitric oxide pathway. Behavior tests for sociability, stereotypy, anxiety, depression, novelty, repetitive and perseverative behavior were carried out between the 14th and 28th day. On the 29th day, animals were sacrificed, and mitochondrial complexes and oxidative stress parameters were evaluated. We also estimated the levels of neuroinflammatory and apoptotic markers such as TNF-α, IL-6, NF-κB, IFN-γ, HSP-70, and caspase-3. To assess the involvement of the nitric oxide pathway, levels of iNOS and homocysteine were estimated. Treatment with NDGA significantly restored behavioral, biochemical, neurological, and molecular deficits. Hence, NDGA can be used as a neurotherapeutic agent in ASD. Targeting nitric oxide pathway mediated oxidative & nitrosative stress responsible for behavioral, biochemical, and molecular alterations via modulating nitric oxide pathway. The evaluation of iNOS and homocysteine levels conclusively establishes the nitric oxide pathway's role in causing behavioral, biochemical & molecular deficits and NDGA's beneficial effect in restoring these alterations.

Cyhalofop-butyl and Glyphosate Multiple-Herbicide Resistance Evolved in an Eleusine indica Population Collected in Chinese Direct-Seeding Rice

Eleusine indica is a typical xerophytic weed species with a cosmopolitan distribution. It is invasive and highly adaptable to diverse habitats and crops. Due to rice cropping-pattern changes, E indica has become one of the main dominant grass weeds infecting direct-seeding paddy fields. A Chinese E. indica population has evolved multiple-herbicide resistance to cyhalofop-butyl and glyphosate. In this study, the multiple-resistance profile of E. indica to these two different types of herbicides and their resistance mechanisms were investigated. Whole-plant dose-response assays indicated that the multiple-herbicide-resistant (MHR) population exhibited 10.8-fold resistance to cyhalofop-butyl and 3.1-fold resistance to glyphosate compared with the susceptible (S) population. ACCase sequencing revealed that the Asp-2078-Gly mutation was strongly associated with E. indica resistance to cyhalofop-butyl. The MHR plants accumulated less shikimic acid than S plants at 4, 6, and 8 days after glyphosate treatment. In addition, no amino acid substitution in the EPSPS gene was found in MHR plants. Further analysis revealed that the relative expression level of EPSPS in MHR plants was 6-10-fold higher than that in S plants following glyphosate treatment, indicating that EPSPS overexpression may contribute to the glyphosate resistance. Furthermore, the effectiveness of nine post-emergence herbicides against E. indica were evaluated, and one PPO inhibitor pyraclonil was identified as highly effective in controlling the S and MHR E. indica populations.

Structural optimization of natural product nordihydroguaretic acid to discover novel analogues as AcrB inhibitors

Drug efflux pumps confer multidrug resistance to dangerous bacterial pathogens which makes these proteins promising drug targets. Herein, we present initial chemical optimization and structure-activity relationship (SAR) data around a previously described efflux pump inhibitor, nordihydroguaretic acid (NDGA). Four series of novel NDGA analogues that target Escherichia coli AcrB were designed, synthesized and evaluated for their ability to potentiate the activity of antibiotics, to inhibit AcrB-mediated substrate efflux and reduce off-target activity. Nine novel structures were identified that increased the efficacy of a panel of antibiotics, inhibited drug efflux and reduced permeabilization of the bacterial outer and inner membranes. Among them, WA7, WB11 and WD6 possessing broad-spectrum antimicrobial sensitization activity were identified as NDGA analogues with favorable properties as potential AcrB inhibitors, demonstrating moderate improvement in potency as compared to NDGA. In particular, WD6 was the most broadly active analogue improving the activity of all four classes of antibacterials tested.

Molecular basis of resistance to ACCase-inhibiting herbicide cyhalofop-butyl in Chinese sprangletop (Leptochloa chinensis (L.) Nees) from China

Chinese sprangletop (Leptochloa chinensis (L.) Nees) is one of the most troublesome grass weeds in rice in China. Seven suspected cyhalofop-butyl-resistant L. chinensis populations were collected from different rice fields with a history of cyhalofop-butyl use. The level of resistance and resistance mechanisms in seven populations were studied. Dose-response tests indicated that five populations (JS3, JS4, JS6, JS7 and JS8) had evolved high-level resistance (26.9 to 123.0-fold) to cyhalofop-butyl compared with the susceptible (S) population, and other two populations (JS2 and JS5) were still sensitive to the herbicide. Two acetyl-coenzyme A carboxylase (ACCase) genes were cloned from each population, and three different ACCase mutations (Ile-1781-Leu, Trp-1999-Cys, and Trp-2027-Cys) in ACCase2 gene were determined in different resistant (R) populations. In addition, no resistance-conferring mutations was detected in the R population (JS7), and ACCase gene expression was similar between the S and R populations. Thus, non-target-site resistance mechanisms may be involved in the JS7 population. Moreover, the patterns of cross-resistance of JS6 (Ile-1781-Leu), JS4 (Trp-1999-Cys), JS8 (Trp-2027-Cys), and JS7 (unknown resistance mechanisms) populations to other ACCase-inhibiting herbicides were determined. The JS6 and JS8 populations showed resistance to fenoxaprop-P-ethyl, metamifop, clethodim and pinoxaden, the JS4 population was resistant to fenoxaprop-P-ethyl, metamifop and pinoxaden, and the JS7 population had resistance only to fenoxaprop-P-ethyl and metamifop. These results indicated the diversity of the target-site mutations in ACCase gene of L. chinensis, and provide a better understanding of cross-resistance in L. chinensis, which would be helpful for the management of cyhalofop-butyl-resistant L. chinensis.

Choline Uptake and Metabolism Modulate Macrophage IL-1β and IL-18 Production

Choline is a vitamin-like nutrient that is taken up via specific transporters and metabolized by choline kinase, which converts it to phosphocholine needed for de novo synthesis of phosphatidylcholine (PC), the main phospholipid of cellular membranes. We found that Toll-like receptor (TLR) activation enhances choline uptake by macrophages and microglia through induction of the choline transporter CTL1. Inhibition of CTL1 expression or choline phosphorylation attenuated NLRP3 inflammasome activation and IL-1β and IL-18 production in stimulated macrophages. Mechanistically, reduced choline uptake altered mitochondrial lipid profile, attenuated mitochondrial ATP synthesis, and activated the energy sensor AMP-activated protein kinase (AMPK). By potentiating mitochondrial recruitment of DRP1, AMPK stimulates mitophagy, which contributes to termination of NLRP3 inflammasome activation. Correspondingly, choline kinase inhibitors ameliorated acute and chronic models of IL-1β-dependent inflammation.

Choline Kinase Alpha (CHKα) as a Therapeutic Target in Pancreatic Ductal Adenocarcinoma: Expression, Predictive Value, and Sensitivity to Inhibitors

Choline kinase α (CHKα) plays a crucial role in the regulation of membrane phospholipid synthesis and has oncogenic properties in vitro. We have analyzed the expression of CHKα in cell lines derived from pancreatic ductal adenocarcinoma (PDAC) and have found increased CHKα expression, associated with differentiation. CHKα protein expression was directly correlated with sensitivity to MN58b, a CHKα inhibitor that reduced cell growth through the induction of apoptosis. Accordingly, CHKα knockdown led to reduced drug sensitivity. In addition, we found that gemcitabine-resistant PDAC cells displayed enhanced sensitivity to CHKα inhibition and, in vitro, MN58b had additive or synergistic effects with gemcitabine, 5-fluorouracil, and oxaliplatin, three active drugs in the treatment of PDAC. Using tissue microarrays, CHKα was found to be overexpressed in 90% of pancreatic tumors. While cytoplasmic CHKα did not relate to survival, nuclear CHKα distribution was observed in 43% of samples and was associated with longer survival, especially among patients with well/moderately differentiated tumors. To identify the mechanisms involved in resistance to CHKα inhibitors, we cultured IMIM-PC-2 cells with increasingly higher concentrations of MN58b and isolated a subline with a 30-fold higher IC50. RNA-Seq analysis identified upregulation of ABCB1 and ABCB4 multidrug resistance transporters, and functional studies confirmed that their upregulation is the main mechanism involved in resistance. Overall, our findings support the notion that CHKα inhibition merits further attention as a therapeutic option in patients with PDAC and that expression levels may predict response.

Phenolic constituents of the Bangladeshi medicinal plant Pothos scandens and their anti-estrogenic, hyaluronidase inhibition, and histamine release inhibitory activities

Extracts from the stem and roots of the Bangladeshi medicinal plant Pothos scandens L. (Araceae) were isolated, and three hemiterpene glucoside aromatic esters, pothobanosides A (1), B (2), and C (3), and a phenylisobutanoid, pothobanol (4), along with 14 known compounds, were characterized. The isolates were tested for their estrogenic/anti-estrogenic activity using the estrogen-responsive human breast cancer cell lines MCF-7 and T47D, and syringoyl derivatives (2, 3, and canthoside B) showed strong inhibitory activity against both cell lines. Their less oxygenated analogs (1, and markhamioside F) were almost inactive. The isolates were also evaluated for hyaluronidase and histamine release inhibitory activities, and pothobanoside A (1) showed significant hyaluronidase inhibitory activity among the isolated compounds, which was similar to that of the positive control rosmarinic acid. Because hyaluronidase produces an angiogenic response that has been implicated in tumor invasiveness and metastasis, 1 could be valuable as an anti-tumor compound with a different mechanism of action from related compounds (2, 3). Pothobanoside C (3) and pothobanol (4) were also found to inhibit histamine release to a similar degree to the positive control epigallocatechin 3-O-(3"-O-methyl)-gallate. The histamine release inhibitory potency of these isolates may support the traditional uses of this plant in folk medicine.

Systemic Proteasome Inhibition Induces Sustained Post-stroke Neurological Recovery and Neuroprotection via Mechanisms Involving Reversal of Peripheral Immunosuppression and Preservation of Blood-Brain-Barrier Integrity

In view of its profound effect on cell survival and function, the modulation of the ubiquitin-proteasome-system has recently been shown to promote neurological recovery and brain remodeling after focal cerebral ischemia. Hitherto, local intracerebral delivery strategies were used, which can hardly be translated to human patients. We herein analyzed effects of systemic intraperitoneal delivery of the proteasome inhibitor BSc2118 on neurological recovery, brain injury, peripheral and cerebral immune responses, neurovascular integrity, as well as cerebral neurogenesis and angiogenesis in a mouse model of transient intraluminal middle cerebral artery occlusion. Systemic delivery of BSc2118 induced acute neuroprotection reflected by reduced infarct volume when delivered up to 9 h post-stroke. The latter was associated with reduced brain edema and stabilization of blood-brain-barrier integrity, albeit cerebral proteasome activity was only mildly reduced. Neuronal survival persisted in the post-acute stroke phase up to 28 days post-stroke and was associated with improved neurological recovery when the proteasome inhibitor was continuously delivered over 7 days. Systemic proteasome inhibition prevented stroke-induced acute leukocytosis in peripheral blood and reversed the subsequent immunosuppression, namely, the reduction of blood lymphocyte and granulocyte counts. On the contrary, post-ischemic brain inflammation, cerebral HIF-1α abundance, cell proliferation, neurogenesis, and angiogenesis were not influenced by the proteasome inhibitor. The modulation of peripheral immune responses might thus represent an attractive target for the clinical translation of proteasome inhibitors.

Multiple-herbicide resistance in Echinochloa crus-galli var. formosensis, an allohexaploid weed species, in dry-seeded rice

Biotypes of Echinochloa crus-galli var. formosensis with resistance to cyhalofop-butyl, an acetyl-CoA carboxylase (ACCase) inhibitor, have been found in dry-seeded rice fields in Okayama, Japan. We collected two lines with suspected resistance (Ecf27 and Ecf108) from dry-seeded rice fields and investigated their sensitivity to cyhalofop-butyl and other herbicides. Both lines exhibited approximately 7-fold higher resistance to cyhalofop-butyl than a susceptible line. Ecf108 was susceptible to penoxsulam, an acetolactate synthase (ALS) inhibitor. On the other hand, Ecf27 showed resistance to penoxsulam and two other ALS inhibitors: propyrisulfuron and pyriminobac-methyl. The alternative herbicides butachlor, thiobencarb, and bispyribac-sodium effectively controlled both lines. To examine the molecular mechanisms of resistance, we amplified and sequenced the target-site encoding genes in Ecf27, Ecf108, and susceptible lines. Partial sequences of six ACCase genes and full-length sequences of three ALS genes were examined. One of the ACCase gene sequences encodes a truncated aberrant protein due to a frameshift mutation in both lines. Comparisons of the genes among Ecf27, Ecf108, and the susceptible lines revealed that none of the ACCases and ALSs in Ecf27 and Ecf108 have amino acid substitutions that are known to confer herbicide resistance, although a single amino acid substitution was found in each of three ACCases in Ecf108. Our study reveals the existence of a multiple-herbicide resistant biotype of E. crus-galli var. formosensis at Okayama, Japan that shows resistance to cyhalofop-butyl and several ALS inhibitors. We also found a biotype that is resistant only to cyhalofop-butyl among the tested herbicides. The resistance mechanisms are likely to be non-target-site based, at least in the multiple-herbicide resistant biotype.

Magnetic resonance spectroscopy for detection of choline kinase inhibition in the treatment of brain tumors

Abnormal choline metabolism is a hallmark of cancer and is associated with oncogenesis and tumor progression. Increased choline is consistently observed in both preclinical tumor models and in human brain tumors by proton magnetic resonance spectroscopy (MRS). Thus, inhibition of choline metabolism using specific choline kinase inhibitors such as MN58b may be a promising new strategy for treatment of brain tumors. We demonstrate the efficacy of MN58b in suppressing phosphocholine production in three brain tumor cell lines. In vivo MRS studies of rats with intracranial F98-derived brain tumors showed a significant decrease in tumor total choline concentration after treatment with MN58b. High-resolution MRS of tissue extracts confirmed that this decrease was due to a significant reduction in phosphocholine. Concomitantly, a significant increase in poly-unsaturated lipid resonances was also observed in treated tumors, indicating apoptotic cell death. MRI-based volume measurements demonstrated a significant growth arrest in the MN58b-treated tumors in comparison with saline-treated controls. Histologically, MN58b-treated tumors showed decreased cell density, as well as increased apoptotic cells. These results suggest that inhibition of choline kinase can be used as an adjuvant to chemotherapy in the treatment of brain tumors and that decreases in total choline observed by MRS can be used as an effective pharmacodynamic biomarker of treatment response.

Harzianolide, a novel plant growth regulator and systemic resistance elicitor from Trichoderma harzianum

A detailed understanding of the effect of natural products on plant growth and protection will underpin new product development for plant production. The isolation and characterization of a known secondary metabolite named harzianolide from Trichoderma harzianum strain SQR-T037 were described, and the bioactivity of the purified compound as well as the crude metabolite extract in plant growth promotion and systemic resistance induction was investigated in this study. The results showed that harzianolide significantly promoted tomato seedling growth by up to 2.5-fold (dry weight) at a concentration of 0.1 ppm compared with the control. The result of root scan suggested that Trichoderma secondary metabolites may influence the early stages of plant growth through better root development for the enhancement of root length and tips. Both of the purified harzianolide and crude metabolite extract increased the activity of some defense-related enzymes to response to oxidative stress. Examination of six defense-related gene expression by real-time reverse transcription-PCR analysis revealed that harzianolide induces the expression of genes involved in the salicylic acid (PR1 and GLU) and jasmonate/ethylene (JERF3) signaling pathways while crude metabolite extract inhibited some gene expression (CHI-II and PGIP) related to basal defense in tomato plants. Further experiment showed that a subsequent challenge of harzianolide-pretreated plants with the pathogen Sclerotinia sclerotiorum resulted in higher systemic resistance by the reduction of lesion size. These results indicate that secondary metabolites of Trichoderma spp., like harzianolide, may play a novel role in both plant growth regulation and plant defense responses.

Combined 5-FU and ChoKα inhibitors as a new alternative therapy of colorectal cancer: evidence in human tumor-derived cell lines and mouse xenografts

Background

Colorectal cancer (CRC) is the third major cause of cancer related deaths in the world. 5-fluorouracil (5-FU) is widely used for the treatment of colorectal cancer but as a single-agent renders low response rates. Choline kinase alpha (ChoKα), an enzyme that plays a role in cell proliferation and transformation, has been reported overexpressed in many different tumors, including colorectal tumors. ChoKα inhibitors have recently entered clinical trials as a novel antitumor strategy.

Methodology/Principal Findings

ChoKα specific inhibitors, MN58b and TCD-717, have demonstrated a potent antitumoral activity both in vitro and in vivo against several tumor-derived cell line xenografts including CRC-derived cell lines. The effect of ChoKα inhibitors in combination with 5-FU as a new alternative for the treatment of colon tumors has been investigated both in vitro in CRC-tumour derived cell lines, and in vivo in mouse xenografts models. The effects on thymidilate synthase (TS) and thymidine kinase (TK1) levels, two enzymes known to play an essential role in the mechanism of action of 5-FU, were analyzed by western blotting and quantitative PCR analysis. The combination of 5-FU with ChoKα inhibitors resulted in a synergistic effect in vitro in three different human colon cancer cell lines, and in vivo against human colon xenografts in nude mice. ChoKα inhibitors modulate the expression levels of TS and TK1 through inhibition of E2F production, providing a rational for its mechanism of action.

Conclusion/Significance

Our data suggest that both drugs in combination display a synergistic antitumoral effect due to ChoKα inhibitors-driven modulation of the metabolization of 5-FU. The clinical relevance of these findings is strongly supported since TCD-717 has recently entered Phase I clinical trials against solid tumors.

A comparison of reactivating efficacy of newly developed oximes (K074, K075) and currently available oximes (obidoxime, HI-6) in cyclosarin-and tabun-poisoned rats

The potency of newly developed oximes (K074, K075) and commonly used oximes (obidoxime, HI-6) to reactivate nerve agent-inhibited acetylcholinesterase was evaluated in rats poisoned with tabun or cyclosarin at a lethal dose corresponding to the LD50 value. In vivo determined percentage of reactivation of tabun-inhibited blood and brain acetylcholinesterase showed that obidoxime is the most efficacious reactivator of tabun-inhibited acetylcholinesterase among studied oximes in the peripheral compartment (blood) although the differences between obidoxime and newly developed oximes were not significant. On the other hand, one of the newly developed oximes (K074) seems to be a significantly more efficacious reactivator of tabun-inhibited acetylcholinesterase in the central compartment (brain) than the other studied oximes. In addition, the oxime HI-6 is unable to sufficiently reactivate tabun-inhibited acetylcholinesterase in rats. In vivo determined percentage of reactivation of cyclosarin-inhibited blood and brain acetylcholinesterase in poisoned rats showed that HI-6 is the most efficacious reactivator of cyclosarin-inhibited acetylcholinesterase among the studied oximes in the peripheral (blood) as well as central (brain) compartment although the differences between the oxime HI-6 and other tested oximes in the brain were not significant. Due to their reactivating effects, both newly developed K-oximes can be considered to be promising oximes for the antidotal treatment of acute tabun poisoning while the oximes HI-6 is still the most promising oxime for the treatment of acute cyclosarin poisonings due to its high potency in reactivating cyclosarin-inhibited acetylcholinesterase in the peripheral as well as central compartment.

Novel series of bispyridinium compounds bearing a (Z)-but-2-ene linker—Synthesis and evaluation of their reactivation activity against tabun and paraoxon-inhibited acetylcholinesterase

Six novel AChE reactivators with a (Z)-but-2-ene linker were synthesized using the known synthetic pathways. Their ability to reactivate AChE, which had been previously inhibited by nerve agent tabun or pesticide paraoxon, was tested in vitro and compared to pralidoxime, HI-6, obidoxime, and K075. The novel synthesized compounds were found to be ineffective against GA-inhibited AChE but the ability of (Z)-1,4-bis(4-hydroxyiminomethylpyridinium)-but-2-ene dibromide to reactivate paraoxon-inhibited AChE was comparable with that of oxime K075. Notably, the oxime group in position four substantially increased the ability of the novel compounds to reactivate paraoxon-inhibited AChE.

In vitro reactivation potency of acetylcholinesterase reactivators--K074 and K075--to reactivate tabun-inhibited human brain cholinesterases

In this work, two oximes for the treatment of tabun-inhibited acetylcholinesterase (AChE; EC 3.1.1.7), K074 (1,4-bis(4-hydroxyiminomethylpyridinium)butane dibromide) and K075 ((E)-1,4-bis(4-hydroxyiminomethylpyridinium)but-2-en dibromide), were tested in vitro as reactivators of AChE. Comparison was made with currently used AChE reactivators (pralidoxime, HI-6, methoxime and obidoxime). Human brain homogenate was taken as an appropriate source of the cholinesterases. As resulted, oxime K074 appears to be the most potent reactivator of tabun-inhibited AChE, with reactivation potency comparable to that of obidoxime. A second AChE reactivator, K075, does not attain as great a reactivation potency as K074, although its maximal reactivation (17%) was achieved at relevant concentrations for humans.

A comparison of the potency of newly developed oximes (K074, K075) and currently available oximes (obidoxime, HI-6) to counteract soman-induced neurotoxicity in rats

The neuroprotective effects of newly developed oximes (K074, K075) and currently available oximes (obidoxime, HI-6) in combination with atropine in rats poisoned with soman were studied. The soman-induced neurotoxicity was monitored using a functional observational battery at 24 h and 7 days after soman challenge. The results indicate that the oxime HI-6 combined with atropine seems to be an effective antidote for a decrease in soman-induced neurotoxicity, whereas the ability of both newly developed oximes (K074, K075) as well as obidoxime to counteract soman-induced acute neurotoxicity is negligible. Due to the absence of their neuroprotective potency, both newly developed oximes are not suitable oximes for antidotal treatment after exposure to soman. The oxime HI-6 is still the best acetylcholinesterase reactivator for the antidotal treatment of acute poisonings with soman.

A new class of nitric oxide-releasing derivatives of cetirizine; pharmacological profile in vascular and airway smooth muscle preparations

BACKGROUND AND PURPOSE

The pharmacological properties of compounds NCX 1512 and NCX 1514, synthesized by linking the histamine H1-receptor antagonist cetirizine to NO-releasing spacer groups, are reported. The aim was to establish if the compounds retained the antihistamine action of the parent compound, to assess their efficacy as NO donors and to test if they had broader antiallergic activity than cetirizine in the lung.

EXPERIMENTAL APPROACH

Antihistamine activity of NCX 1512 and NCX 1514 was investigated in vitro in the guinea pig ileum, in tracheal rings (GPTR) and lung parenchymal strips (GPLP) of the guinea-pig. The NO-releasing capacity was investigated in vascular preparations; the isolated rabbit and guinea-pig aorta and guinea-pig pulmonary artery. Kinetics of NO release were assessed in a rat whole blood assay.

KEY RESULTS

Both NCX 1512 and NCX 1514 retained activity as H1-receptor antagonists in the guinea pig ileum and airway preparations. The NO-releasing NCX compounds relaxed the rabbit aorta, an action prevented by the guanylyl cyclase inhibitor ODQ (10 microM). NCX 1512 and NCX 1514 did not relax the antigen (ovalbumin) pre-contracted GPTR, whereas the NO donors NCX 2057 and DEA-NONOate relaxed guinea-pig pre-contracted vascular and tracheal preparations. Cetirizine (1-100 microM) and NCX 1512 (1-100 microM) reduced the cumulative (0.01-100 microg ml(-1)) ovalbumin-induced constriction in GPTR, but had no significant effect in GPLP.

CONCLUSIONS AND IMPLICATIONS

NCX 1512 and NCX 1514 act as antihistamines and NO donors. However, there was no improved effect compared to cetirizine on antigen-induced constriction of the central and peripheral lung.

Heme oxygenase inhibition by 2-oxy-substituted 1-(1H-imidazol-1-yl)-4-phenylbutanes: effect of halogen substitution in the phenyl ring

A series of 2-oxy-substituted 1-(1H-imidazol-1-yl)-4-phenylbutanes comprising imidazole-ketones, imidazole-dioxolanes, and imidazole-alcohols substituted with halogens in the phenyl ring were synthesized and evaluated as novel inhibitors of heme oxygenase which are structurally distinct from metalloporphyrins. The entire library of compounds was found to be highly active, with the bromine- and iodine-substituted derivatives being the most potent. The imidazole-dioxolanes were all selective for the HO-1 isozyme (inducible) and exhibited substantially lower activity toward the HO-2 isozyme (constitutive). The corresponding imidazole-ketones and imidazole-alcohols showed selectivity toward HO-1 to a lesser degree than the similarly substituted imidazole-dioxolanes.

The evaluation of neuroprotective efficacy of newly developed oximes (K074, K075) and currently available oximes (obidoxime, HI-6) in cyclosarin-poisoned rats

The neuroprotective effects of newly developed oximes (K074, K075) and currently available oximes (obidoxime, HI-6) in combination with atropine in rats poisoned with cyclosarin were studied. The cyclosarin-induced neurotoxicity was monitored using a functional observational battery at 24 h and 7 days following cyclosarin challenge. The results indicate that the oxime HI-6 combined with atropine seems to be the most effective antidote for a decrease in cyclosarin-induced neurotoxicity. Both newly developed oximes (K074, K075) as well as obidoxime are also able to counteract cyclosarin-induced acute neurotoxicity, but their neuroprotective potency is significantly lower compared with the oxime HI-6. Therefore, the oxime HI-6 is still the most suitable oxime for the antidotal treatment of acute poisonings with cyclosarin due to its neuroprotective as well as reactivating efficacy.

A comparison of the potency of newly developed oximes (K074, K075) and commonly used oximes (obidoxime, HI-6) to counteract tabun-induced neurotoxicity in rats

The neuroprotective effects of newly developed oximes (K074, K075) and currently available oximes (obidoxime, HI-6) in combination with atropine in rats poisoned with tabun at a sublethal dose (180 micro g/kg i.m.; 80% LD(50)) were studied. The tabun-induced neurotoxicity was monitored using a functional observational battery and an automatic measurement of motor activity. The neurotoxicity of tabun was monitored at 24h and 7 days following tabun challenge. The results indicate that all oximes studied in combination with atropine allow all tabun-poisoned rats to survive within 7 days following tabun challenge while two non-treated tabun-poisoned rats died within 2h. Both newly developed oximes combined with atropine seem to be effective antidotes for a decrease in tabun-induced neurotoxicity in the case of sublethal poisoning although they are not able to eliminate tabun-induced neurotoxicity completely. The oxime K075 showed a higher neuroprotective efficacy against tabun than K074 according to the number of eliminated tabun-induced neurotoxic signs at 24h as well as 7 days after tabun challenge. The neuroprotective efficacy of obidoxime in combination with atropine is similar to the potency of newly developed oxime K075 but the ability of the oxime HI-6 to counteract tabun-induced acute neurotoxicity is significantly lower at 24h as well as 7 days after tabun poisoning. Due to their neuroprotective effects, both newly developed oximes (especially K075) appear to be more suitable oximes for the antidotal treatment of acute tabun poisonings than the oxime HI-6.

Combined effect of proteasome and calpain inhibition on cisplatin-resistant human melanoma cells

Resistance of tumor cells to cisplatin is a common feature frequently encountered during chemotherapy against melanoma caused by various known and unknown mechanisms. To overcome drug resistance toward cisplatin, a targeted treatment using alternative agents, such as proteasome inhibitors, has been investigated. This combination could offer a new therapeutic approach. Here, we report the biological effects of proteasome inhibitors on the parental cisplatin-sensitive MeWo human melanoma cell line and its cisplatin-resistant MeWo(cis1) variant. Our experiments show that proteasome inhibitor treatment of both cell lines impairs cell viability at concentrations that are not toxic to primary human fibroblasts in vitro. However, compared with the parental MeWo cell line, significantly higher concentrations of proteasome inhibitor are required to reduce cell viability of MeWo(cis1) cells. Moreover, whereas proteasome activity was inhibited to the same extent in both cell lines, IkappaBalpha degradation and nuclear factor-kappaB (NF-kappaB) activation in MeWo(cis1) cells was proteasome inhibitor independent but essentially calpain inhibitor sensitive. In support, a calpain-specific inhibitor impaired NF-kappaB activation in MeWo(cis1) cells. Here, we show that cisplatin resistance in MeWo(cis1) is accompanied by a change in the NF-kappaB activation pathway in favor of calpain-mediated IkappaBalpha degradation. Furthermore, combined exposure to proteasome and calpain inhibitor resulted in additive effects and a strongly reduced cell viability of MeWo(cis1) cells. Thus, combined strategies targeting distinct proteolytic pathways may help to overcome mechanisms of drug resistance in tumor cells.

Effects of the somatostatin receptor subtype 4 selective agonist J-2156 on sensory neuropeptide release and inflammatory reactions in rodents

BACKGROUND AND PURPOSE

Substance P (SP) and calcitonin gene-related peptide (CGRP) released from capsaicin-sensitive sensory nerves induce local neurogenic inflammation; somatostatin exerts systemic anti-inflammatory actions presumably via sst4/sst1 receptors. This study investigates the effects of a high affinity, sst4-selective, synthetic agonist, J-2156, on sensory neuropeptide release in vitro and inflammatory processes in vivo.

EXPERIMENTAL APPROACH

Electrically-induced SP, CGRP and somatostatin release from isolated rat tracheae was measured with radioimmunoassay. Mustard oil-induced neurogenic inflammation in rat hindpaw skin was determined by Evans blue leakage and in the mouse ear with micrometry. Dextran-, carrageenan- or bradykinin-induced non-neurogenic inflammation was examined with plethysmometry or Evans blue, respectively. Adjuvant-induced chronic arthritis was assessed by plethysmometry and histological scoring. Granulocyte accumulation was determined with myeloperoxidase assay and IL-1beta with ELISA.

KEY RESULTS

J-2156 (10-2000 nM) diminished electrically-evoked neuropeptide release in a concentration-dependent manner. EC50 for the inhibition of substance P, CGRP and somatostatin release were 11.6 nM, 14.3 nM and 110.7 nM, respectively. J-2156 (1-100 microg kg(-1) i.p.) significantly, but not dose-dependently, inhibited neurogenic and non-neurogenic acute inflammatory processes and adjuvant-induced chronic oedema and arthritic changes. Endotoxin-evoked myeloperoxidase activity and IL-1beta production in the lung, but not IL-1beta- or zymosan-induced leukocyte accumulation in the skin were significantly diminished by J-2156.

CONCLUSIONS AND IMPLICATIONS

J-2156 acting on sst4 receptors inhibits neuropeptide release, vascular components of acute inflammatory processes, endotoxin-induced granulocyte accumulation and IL-1beta synthesis in the lung and synovial and inflammatory cells in chronic arthritis. Therefore it might be a promising lead for the development of novel anti-inflammatory drugs.

Analgesic effects of the somatostatin sst4 receptor selective agonist J-2156 in acute and chronic pain models

Somatostatin released from capsaicin-sensitive afferents exerts systemic anti-nociceptive actions, presumably via somatostatin receptor subtype 4 (sst4). In the present study, the antinociceptive effects of a novel somatostatin sst4 receptor selective peptidomimetic compound, J-2156 (1-100 microg/kg i.p.), were examined. J-2156 inhibited nocifensive behaviour of mice in the second phase of the formalin test. Adjuvant-evoked chronic inflammatory mechanical allodynia was decreased in rats treated with J-2156 for 21 days. Sciatic nerve ligation-induced neuropathic mechanical hyperalgesia was inhibited by J-2156 on the seventh postoperative day. Results obtained using this highly selective agonist suggest that somatostatin sst4 receptors represent a promising target for new perspectives in analgesic therapy.

Modulation of iNOS expression by a nitric oxide-releasing derivative of the natural antioxidant ferulic acid in activated RAW 264.7 macrophages

We have previously reported that NCX 2057, a new chemical entity bearing a nitric oxide (NO)-releasing moiety linked to the natural antioxidant ferulic acid, shows marked anti-inflammatory properties in a model of chronic brain inflammation. We have now studied the effects of NCX 2057 and its metabolic products, ferulic acid and NCX 2059, on inducible nitric oxide synthase (iNOS) expression and function in lipopolysaccharide/interferon-gamma (LPS/IFNgamma)-stimulated RAW 264.7 macrophages. NCX 2057 inhibited iNOS mRNA and protein expression (IC(50)=6.2+/-1.0 microM) without altering iNOS protein degradation rate. NCX 2057 also decreased the levels of LPS/IFNgamma-induced nitrite accumulation (IC(50)=4.3+/-0.7 microM) in RAW 264.7 cells. Conversely, NCX 2059, which does not possess NO-donating properties, was only weakly effective (IC(50) >100 microM) and ferulic acid was inactive. To understand further the mechanisms underlying anti-inflammatory properties we studied the effects of NCX 2057 on selected transcription factors. Unlike ferulic acid, NCX 2057 inhibited LPS-induced translocation/activation of the nuclear factor, NF-kappaB, while other transcription factors, such as, Sp1, NF-IL2A and STAT-1 were not affected. The present data support the concept that NO adds important anti-inflammatory properties to ferulic acid. Thus, NCX 2057 represents a new prototype drug for the treatment of disorders associated with chronic inflammation and oxidative stress.

Noninvasive Magnetic Resonance Spectroscopic Pharmacodynamic Markers of the Choline Kinase Inhibitor MN58b in Human Carcinoma Models

MN58b is a novel anticancer drug that inhibits choline kinase, resulting in inhibition of phosphocholine synthesis. The aim of this work was to develop a noninvasive and robust pharmacodynamic biomarker for target inhibition and, potentially, tumor response following MN58b treatment. Human HT29 (colon) and MDA-MB-231 (breast) carcinoma cells were examined by proton (1H) and phosphorus (31P) magnetic resonance spectroscopy (MRS) before and after treatment with MN58b both in culture and in xenografts. An in vitro time course study of MN58b treatment was also carried out in MDA-MB-231 cells. In addition, enzymatic assays of choline kinase activity in cells were done. A decrease in phosphocholine and total choline levels (P < 0.05) was observed in vitro in both cell lines after MN58b treatment, whereas the inactive analogue ACG20b had no effect. In MDA-MB-231 cells, phosphocholine fell significantly as early as 4 hours following MN58b treatment, whereas a drop in cell number was observed at 48 hours. Significant correlation was also found between phosphocholine levels (measured by MRS) and choline kinase activities (r2 = 0.95, P = 0.0008) following MN58b treatment. Phosphomonoesters also decreased significantly (P < 0.05) in both HT29 and MDA-MB-231 xenografts with no significant changes in controls. 31P-MRS and 1H-MRS of tumor extracts showed a significant decrease in phosphocholine (P < or = 0.05). Inhibition of choline kinase by MN58b resulted in altered phospholipid metabolism both in cultured tumor cells and in vivo. Phosphocholine levels were found to correlate with choline kinase activities. The decrease in phosphocholine, total choline, and phosphomonoesters may have potential as noninvasive pharmacodynamic biomarkers for determining tumor response following treatment with choline kinase inhibitors.

Basis of selectivity of cyhalofop-butyl in Oryza sativa L

Cyhalofop-butyl (CB), 2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid, butyl ester (R), is an aryloxyphenoxypropionate (AOPP) herbicide for postemergence use in rice to control grasses, mainly Echinochloa spp. Similar to other AOPP and cyclohexanedione herbicides, the site of action of CB is acetyl-coenzyme A carboxylase (ACCase), an enzyme in fatty acid biosynthesis. The mechanisms involved in the selectivity of CB in rice (Oryza sativa L.)-absorption, translocation, metabolism, and ACCase susceptibility-were studied. Studies of in vitro inhibition of ACCase in E. oryzoides and O. sativa L. species discounted any differential active site sensitivity as the basis of tolerance to CB. The O. sativa L. cuticle was uniformly covered by waxes, with predominantly unshaped large waxes randomly distributed, obtaining absorption values of under 30%, 24 h after application (HAA). The E. oryzoides cuticle formed a non-uniform covered reticule, with less wax density and areas lacking in waxes reaching maximum values of absorption rising to 73%, 24 HAA. Translocation studies revealed no significant differences, either between species, or between times, remaining in the treated leaf. There was a good correlation between the rate of metabolism and plant tolerance. Plant metabolism studies demonstrated that tolerant rice inactivated the esterases producing a lack of functionality thus reducing the conversion of CB to cyhalofop acid, which is the active form of the herbicide. Moreover, it increased the metabolism of the herbicide forming non toxic metabolites much faster than E. oryzoides. It was concluded that the basis of rice tolerance to CB was a lack of esterase functionality, a reduced absorption through the cuticle and an increase in cyhalofop acid metabolism.

Hemodynamic effects of di-sec-butyl phenol, an anesthetic substituted phenol

Dose- and age-related hemodynamic effects were determined for an anesthetic substituted phenol, 2,6-di-sec-butyl phenol (DSB). DSB, 7.5 mg/kg, induced hypnosis in young rabbits and increased mean blood pressure to 170 +/- 14% and heart rate to 150 +/- 21% of control values. In elderly rabbits, 7.5 mg/kg DSB induced hypnosis, had no effect on blood pressure, but increased the heart rate to 130 +/- 2% of control. After ganglionic blockade with hexamethonium, 7.5 mg/kg DSB caused a decline in mean blood pressure (71 +/- 5% of control) without change in heart rate. DSB increased norepinephrine release from SH-SY5Y cells, a human neuroblastoma cell line (5.4 +/- 1.7% vs. 3.5 +/- 0.3%). DSB produced age-dependent elevation of mean blood pressure in rabbits, probably by causing release of catecholamines from the sympathetic nervous system.

Differential efficacies of somatostatin receptor agonists for G-protein activation and desensitization of somatostatin receptor subtype 4-mediated responses

Although desensitization represents an important physiological feedback mechanism that protects against overstimulation, it can significantly limit the therapeutic usefulness of drugs. In the current investigation, we have employed Cytosensor microphysiometry for the purpose of determining the propensity of somatostatin receptor agonists to induce desensitization of the human somatostatin receptor subtype 4 (h sst4)-mediated extracellular acidification rate (EAR) response in intact Chinese hamster ovary (CHO) cells. We have compared this propensity with the efficacies of the agonists as measured in a [35S]guanosine-5'-O-(3-thio)triphosphate binding assay with membranes of the same CHO-h sst4 cell line. We observed that (1'S,2S)-4-amino-N-(1'-carbamoyl-2'-phenylethyl)-2-(4''-methyl-1''-naphthalenesulfonylamino)butanamide (J-2156), a superagonist at the h sst4 with higher efficacy than somatostatin-14 itself (Engström et al., 2005), was considerably less prone to cause desensitization of the EAR response than somatostatin-14, somatostatin-28, and cortistatin-17. In contrast, compound A (methyl (2S)-5-{[amino(imino)methyl]amino}-2-{[4-[5-7-difluoro-2-phenyl-1H-indol-3-yl)butanoyl]amino}-pentanoate), which we also found to be an h sst(4) superagonist, albeit to a lesser degree than J-2156, demonstrated a high propensity to cause desensitization. Our results indicate that there is no relationship between the efficacy of the agonists to cause G-protein activation and their ability to induce desensitization of the h sst4-mediated EAR responses. The finding that on the h sst4, J-2156 is not only a superagonist but also shows a low propensity to cause desensitization, might offer therapeutic advantages. At a minimum, the compound will be a powerful tool to study the mechanisms connected to efficacy and desensitization of h sst4-mediated responses.

Antimicrobial activity of 1,2-bis-[2-(5-R)-1H-benzimidazolyl]-1,2-ethanediols, 1,4-bis-[2-(5-R)-1H-benzimidazolyl]-1,2,3,4-butanetetraols and their FeIII, CuII, and AgI complexes

1,2-Bis-[2-(5-H/Me/Cl/NO2)-1H-benzimidazolyl]-1,2-ethanediols (L1-L4), 1,4-Bis-[2-(5-H/Me/Cl)-1H-benzimidazolyl]-1,2,3,4-butanetetraols (L5-L7) and their complexes with FeCl3, CuCl2, and AgNO3 were synthesized; antibacterial activity of the compounds was determined toward Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri, Proteus mirabilis, and antifungal activity against Candida albicans. The AgI complexes have considerable activity toward the microorganisms. Some AgI complexes show higher activity toward S. epidermidis than AgNO3 and cefuroxime. Cu(L3)Cl2 and Fe(L3)Cl3 show an antifungal effect on C. albicans but L3 itself has no activity.

Antimicrobial activity of ZnII, CdII, and HgII complexes of 1,2-bis-[2-(5-R)-1H-benzimidazolyl]-1,2-ethanediols and 1,4-bis-[2-(5-R)-1H-benzimidazolyl]-1,2,3,4-butanetetraols

1,2-Bis-[2-(5-H/Me/Cl/NO2)-1H-benzimidazolyl]-1,2-ethanediols (L1-L4), 1,4-bis-[2-(5-H/Me/Cl)-1H-benzimidazolyl]-1,2,3,4-butanetetraols (L5-L7) and their complexes with ZnCl2, CdCl2 and HgCl2 were synthesized and antibacterial activity of the compounds was tested toward Staphylococcus aureus, S. epidermidis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri, Proteus mirabilis and antifungal activity against Candida albicans. HgII complexes have a considerably higher antimicrobial activity against all microorganisms. Some HgII complexes show higher antifungal activity than clotrimazole toward C. albicans. Zn2(L3)Cl4, Zn2(L4)Cl4, and Cd(L3)Cl2 were moderately effective against S. aureus and S. epidermidis; Cd(L4)Cl2 exhibited a weak activity only against S. epidermidis.

Product and product-independent induction of butane oxidation in Pseudomonas butanovora

Pseudomonas butanovora grows on butane by means of an inducible soluble alkane monooxygenase (sBMO). The induction of sBMO was studied using the wild type and a sBMO reporter strain. The reporter strain has the lacZ::kan cassette inserted into bmoX, the gene that encodes the alpha-subunit of the hydroxylase of sBMO. The beta-galactosidase activity in the reporter strain was not induced by butane, but was induced by 1-butanol and butyraldehyde. P. butanovora expressed sBMO product-independent activity at 3.0+/-1 nmol ethylene oxide min(-1) mg protein(-1) in stationary phase. The sBMO product-independent activity likely primes the expression of sBMO by butane.

3-(2-Ethoxy-4-{4-[3-hydroxy-2-methyl-4-(3-methylbutanoyl)phenoxy]butoxy}phenyl)propanoic acid: a brain penetrant allosteric potentiator at the metabotropic glutamate receptor 2 (mGluR2)

We have identified and synthesized a brain penetrant propanoic acid as an allosteric potentiator of the metabotropic glutamate receptor 2. Structure-activity relationship studies directed toward improving the potency, level of potentiation and brain penetration led to the discovery of 8 (EC50=1200 nM, 77% potentiation, 119% brain/plasma in rat, 20 mpk i.p., brain level of 5700 nM).

Synthesis and evaluation of CCR5 antagonists containing modified 4-piperidinyl-2-phenyl-1-(phenylsulfonylamino)-butane

Synthesis of analogs containing more rigid bicyclic piperidine replacements for the 4-benzyloxycarbonyl-(ethyl)amino-piperidine moiety of the CCR5 antagonist structure, 1, is described. Although similar binding affinity to the lead was achieved with some analogs they were overall less potent anti-HIV agents suggesting that other features besides CCR5 binding are required for good anti-viral activity.

Synthesis and antiparasitic properties of new 4-N-benzylamino-4-hetarylbut-1-enes

New derivatives of 4-N-benzylamino-4-hetarylbut-1-ene containing a pyridyl nucleus were synthesized from benzylamines and pyridine aldehydes. N-oxide derivatives were obtained from these homoallylamines. Study of the antiparasitic properties of obtained pyridine derivatives as well as of four related benzazepines previously described, was carried out using cytotoxicity assays against Trichomonas vaginalis and epimastigote form of Trypanosoma cruzi protozoa. Compounds showing activity against epimastigote T. cruzi were tested against the amastigote form; unspecific cytotoxicity against macrophages was also studied.

Enantiomerically pure [1, 2-diamino-1-(4-fluorophenyl)butane]platinum(II) complexes: synthesis and antitumor activity against MCF-7 and MDA-MB 231 breast cancer and LnCaP/FGC prostate cancer cell lines

Enantiomerically pure 1, 2-diamino-1-(4-fluorophenyl)butanes were synthesized by stereoselective procedures. The enantiomeric purity was determined by (1)H NMR spectroscopy after derivatization with (1R)-myrtenal. For the coordination to platinum, the diamines were reacted with K(2)PtI(4). Reaction with Ag(2)SO(4) yielded the respective sulfatoplatinum(II) complexes, which were converted into the dichloroplatinum(II) complexes by treatment with 2 N HCl. The influence of the configuration and the kind of leaving group on the antitumor activity was studied on the MCF-7 and MDA-MB 231 breast cancer cell lines, as well as on the LnCaP/FGC prostate cancer cell line. It was demonstrated that the dichloroplatinum(II) complexes were more active than the respective diiodoplatinum(II) derivatives. Conversion into the sulfatoplatinum(II) complexes further enhanced the antiproliferative effects. The configuration determined the antitumor effects, dependent on the cell line used: MCF-7: (R, R) > (S, S) > (R, S) > (S, R); MDA-MB 231: (S, S) > (R, R) > (R, S) = (S, R); LnCaP/FGC: (S, S) > (R, R) > (R, S) > (S, R).

Effective bisquaternary reactivators of tabun-inhibited AChE

Two cholinesterase reactivators (K074 and K075) were synthesized and their reactivation efficacy against tabun-inhibited acetylcholinesterase of the rat brain was tested in vitro. Comparing this efficacy showed that commonly used oximes (pralidoxim, obidoxime and HI-6) were practically without reactivation potency. On the other hand, oximes K074, K075 and trimedoxime were satisfactorily effective. Moreover, K-oximes reactivated tabun-inhibited AChE at lower concentration (10(-4) and 10(-3) m) in comparison with trimedoxime (10(-3) and 10(-2) m). Thus, K-oximes can be considered as the most effective reactivators of tabun-inhibited AChE at present.

Molecular docking and 3D QSAR studies on 1-amino-2-phenyl-4-(piperidin-1-yl)-butanes based on the structural modeling of human CCR5 receptor

In the present study, we have used an approach combining protein structure modeling, molecular dynamics (MD) simulation, automated docking, and 3D QSAR analyses to investigate the detailed interactions of CCR5 with their antagonists. Homology modeling and MD simulation were used to build the 3D model of CCR5 receptor based on the high-resolution X-ray structure of bovine rhodopsin. A series of 64 CCR5 antagonists, 1-amino-2-phenyl-4-(piperidin-1-yl)-butanes, were docked into the putative binding site of the 3D model of CCR5 using the docking method, and the probable interaction model between CCR5 and the antagonists were obtained. The predicted binding affinities of the antagonists to CCR5 correlate well with the antagonist activities, and the interaction model could be used to explain many mutagenesis results. All these indicate that the 3D model of antagonist-CCR5 interaction is reliable. Based on the binding conformations and their alignment inside the binding pocket of CCR5, three-dimensional structure-activity relationship (3D QSAR) analyses were performed on these antagonists using comparative molecular field analysis (CoMFA) and comparative molecular similarity analysis (CoMSIA) methods. Both CoMFA and CoMSIA provide statistically valid models with good correlation and predictive power. The q(2)(r(cross)(2)) values are 0.568 and 0.587 for CoMFA and CoMSIA, respectively. The predictive ability of these models was validated by six compounds that were not included in the training set. Mapping these models back to the topology of the active site of CCR5 leads to a better understanding of antagonist-CCR5 interaction. These results suggest that the 3D model of CCR5 can be used in structure-based drug design and the 3D QSAR models provide clear guidelines and accurate activity predictions for novel antagonist design.

Superagonism at the human somatostatin receptor subtype 4

We have discovered a novel compound, J-2156 [(1'S, 2S)-4-amino-N-(1'-carbamoyl-2'-phenylethyl)-2-(4''-methyl-1''-naphthalenesulfonylamino)butanamide], that belongs to a new class of somatostatin receptor ligands. J-2156 binds with nanomolar affinity to the human somatostatin receptor subtype 4 and is over 400-fold subtype-selective against the other somatostatin receptors. When evaluated in a [(35)S]guanosine-5'-O-(3-thio) triphosphate binding assay, J-2156 elicited a response 2 to 3 times as large as that of somatostatin-28 and somatostatin-14. That somatostatin-14 is clearly not a maximally efficacious agonist could be verified by demonstrating that it displays the typical behavior of a partial agonist when tested against J-2156. Increasing concentrations of somatostatin-14 cause a concentration-dependent rightward shift of the dose-response curves for J-2156, without affecting its maximal response. This lack of reduction of the maximal response and the fact that the superior efficacy of J-2156 is detected in membranes argue against desensitization and internalization as possible explanations for the superior efficacy of J-2156. More likely is that somatostatin-14 and J-2156 stabilize distinct receptor conformations that differ in their ability to interact with G-proteins. In a cyclic AMP assay, J-2156, somatostatin-28, and somatostatin-14 all act as full agonists. However, this outcome is most likely due to the presence of a receptor reserve in the cyclic AMP assay since there is a large gain of apparent potency in the cyclic AMP assay and the gain is larger for J-2156 than for somatostatin. We conclude that the endogenous ligands somatostatin-14 and somatostatin-28 do not define maximal agonism on the human somatostatin receptor subtype 4 and that J-2156 represents a so-called superagonist.

Attenuation of chronic neuroinflammation by a nitric oxide-releasing derivative of the antioxidant ferulic acid

Chronic neuroinflammation and oxidative stress contribute to the neurodegeneration associated with Alzheimer's disease and represent targets for therapy. Ferulic acid is a natural compound that expresses antioxidant and anti-inflammatory activities. Nitric oxide is also a key modulator of inflammatory responses. Grafting a nitric oxide-releasing moiety onto anti-inflammatory drugs results in enhanced anti-inflammatory activity. We compared the effectiveness of ferulic acid with a novel nitric oxide-releasing derivative of ferulic acid in an animal model of chronic neuroinflammation that reproduces many interesting features of Alzheimer's disease. Lipopolysaccharide was infused into the 4th ventricle of young rats for 14 days. Various doses of ferulic acid or its nitric oxide-releasing derivative were administered daily. Both drugs produced a dose-dependent reduction in microglia activation within the temporal lobe. However, the nitric oxide-releasing ferulic acid derivative was significantly more potent. If we delayed the initiation of therapy for 14 days, we found no reduction in microglial activation. In addition, both drugs demonstrated antioxidant and hydroxyl radical scavenging abilities in in vitro studies. Overall, our results predict that a treatment using nitric oxide-releasing ferulic acid may attenuate the processes that drive the pathology associated with Alzheimer's disease if the treatment is initiated before the neuroinflammatory processes can develop.

N-(4-[4-(2,3-dichlorophenyl)piperazin-1-yl]butyl, butenyl and butynyl)arylcarboxamides as novel dopamine D(3) receptor antagonists

The dopamine D(3) receptor subtype has been targeted as a potential neurochemical modulator of the behavioral actions of psychomotor stimulants, such as cocaine. Previous synthetic studies provided structural requirements for high affinity binding to D(3) receptors which included a 2,3-dichloro-phenylpiperazine linked to an arylamido function via a butyl chain. To reduce lipophilicity of these agents and further investigate optimal conformation, a second series of 15 novel ligands was designed that included heteroaromatic substitution and unsaturated alkyl linkers. These compounds were synthesized and evaluated for binding at rat D(3) and D(2) receptors stably expressed in Sf9 cells. D(3) binding affinities ranged from K(i)=0.6-1080 nM, with a broad range of D(3)/D(2) selectivities (2-97). The discovery of potent, selective and bioavailable D(3) receptor ligands will provide essential molecular probes to elucidate the role D(3) receptors play in the psychomotor stimulant and reinforcing effects of cocaine.

Modulation of GABA(A) receptor function by nonhalogenated alkane anesthetics: the effects on agonist enhancement, direct activation, and inhibition

At clinically relevant concentrations, ethers, alcohols, and halogenated alkanes enhance agonist action on the gamma-aminobutyric acid(A) (GABA(A)) receptor, whereas nonhalogenated alkanes do not. Many anesthetics also directly activate and/or inhibit GABA(A) receptors, actions that may produce important behavioral effects; although, the effects of nonhalogenated alkane anesthetics on GABA(A) receptor direct activation and inhibition have not been studied. In this study, we assessed the abilities of two representative nonhalogenated alkanes, cyclopropane and butane, to enhance agonist action, directly activate, and inhibit currents mediated by expressed alpha(1)beta(2)gamma(2L) GABA(A) receptors using electrophysiological techniques. Our studies reveal that cyclopro- pane and butane enhance agonist action on the GABA(A) receptor at concentrations that exceed those required to produce anesthesia. Neither nonhalogenated alkane directly activated nor inhibited GABA(A) receptors, even at concentrations that approach their aqueous saturated solubilities. These results strongly suggest that the behavioral actions of nonhalogenated alkane anesthetics do not result from their abilities to enhance agonist actions, directly activate, or inhibit alpha(1)beta(2)gamma(2L) GABA(A) receptors and are consistent with the hypothesis that electrostatic interactions between anesthetics and their protein binding sites modulate GABA(A) receptor potency.

IMPLICATIONS

When normalized to either their in vivo anesthetic potencies or hydrophobicities, cyclopropane and butane are 1-1.5 orders of magnitude less potent enhancers of agonist action on alpha(1beta2gamma2L) GABA(A) receptors than isoflurane. Additionally, cyclopropane and butane fail to directly activate or inhibit receptors, even at near aqueous saturating concentrations. Thus, it is unlikely that either enhancement or inhibition of the most common GABA(A) receptor subtype in the brain accounts for the behavioral activities of cyclopropane and butane.

CPI-1189. Centaur

The efficacy of the proapoptotic cytokine tumor necrosis factor (TNF) alpha-inhibiting compound CPI-1189 has been demonstrated in various cell culture and animal models of chronic neurodegenerative and inflammatory diseases. CPI-1189 intracellularly inhibits the p38 mitogen-activated protein kinase phosphoactivation, thereby protecting against TNF alpha-induced neurodegeneration. Clinical proof-of-concept phase IIa trials in patients with Parkinson's disease and AIDS dementia complex were successful. These studies demonstrated clinical relevance for treatment with CPI-1189 (50 to 100 mg/day), which attenuated the deterioration in cognitive and/or motor function without any relevant side effects. Since the importance of neuroprotection is emerging, in particular in neurodegenerative diseases with concomitant observed immunological pro-apoptotic alterations in the central nervous system, long-term application of CPI-1189 could represent a promising future therapeutic alternative, in addition to neuroprotective compounds such as selegiline.

Nonhalogenated alkanes cyclopropane and butane affect neurotransmitter-gated ion channel and G-protein-coupled receptors: differential actions on GABAA and glycine receptors

BACKGROUND

Anesthetic mechanisms of nonhalogenated alkanes cyclopropane and butane are not understood. This study was designed to look at which neurotransmitter receptors are possible targets for these anesthetics.

METHODS

Effects of cyclopropane and butane on eight recombinant receptors expressed in Xenopus oocytes were examined electrophysiologically. To address molecular mechanisms of interaction with glycine and gamma-aminobutyric acid type A (GABA(A)) receptors, cyclopropane was further tested on alpha1(S267C) glycine receptor and alpha2(S270X)beta1 GABA(A) receptors that were mutated to amino acids with larger side chains.

RESULTS

Cyclopropane (1, 2, and 5 minimum alveolar concentration [MAC]) potentiated glycine responses by 39, 62, and 161%, respectively, and butane (1 MAC) potentiated by 64% with an increase in apparent affinity for glycine, but yielded barely detectable potentiation of GABA(A) receptors. The efficacy of cyclopropane for glycine receptors was less than isoflurane and halothane. The potentiation by cyclopropane was eliminated for the alpha1(S267C) glycine receptor. Mutant GABA(A) receptors in which the corresponding amino acid was substituted with larger amino acids did not produce significant potentiation. Cyclopropane and butane inhibited nicotinic acetylcholine and N-methyl-D-aspartate receptors, potentiated G-protein-coupled inwardly rectifying potassium channels, and did not change 5-hydroxytryptamine(3A) or muscarinic(1) receptor function. Only cyclopropane markedly inhibited alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors.

CONCLUSIONS

Glycine, nicotinic acetylcholine, and N-methyl-D-aspartate receptors are sensitive to nonhalogenated alkanes, and the authors propose that glycine and N-methyl-D-aspartate receptors are good candidates for anesthetic immobility. The authors also suggest that the distinct effects on glycine and GABA(A) receptors are not due to the small volumes of these anesthetics.

Molecular analysis of the soluble butane monooxygenase from 'Pseudomonas butanovora'

'Pseudomonas butanovora' is capable of growth with butane via the oxidation of butane to 1-butanol, which is catalysed by a soluble butane monooxygenase (sBMO). In vitro oxidation of ethylene (an alternative substrate for sBMO) was reconstituted in the soluble portion of cell extracts and was NADH-dependent. Butane monooxygenase was separated into three components which were obligately required for substrate oxidation. The N-terminal sequences of the peptides associated with butane monooxygenase led to the cloning and sequencing of the 5797 nucleotide bmo gene cluster. Comparisons of the deduced amino acid sequences with other multicomponent monooxygenases suggest that sBMO is a multimeric hydroxylase with 61, 45 and 19 kDa subunits encoded by bmoXYZ, a 40 kDa oxidoreductase encoded by bmoC, and a 15 kDa regulatory protein encoded by bmoB. A sixth structural gene (bmoD) encodes a 9.6 kDa protein with similarity exclusively to mmoD (orfY), a putative metal centre assembly protein of the soluble methane monooxygenases. Insertional inactivation of bmoX resulted in a mutant 'P. butanovora' strain incapable of growth with butane. A putative promoter element characteristic of promoters associated with sigma(54)-dependent transcription initiation was located upstream of the bmo genes. Expression of all six genes was detected in butane-induced cells. Butane monooxygenase from 'P. butanovora' aligns most closely with non-haem carboxylate-bridged diiron monooxygenases and, moreover, contains the characteristic iron-binding motif. The structural and mechanistic implications of the high sequence identity (up to 64%) between the peptides of butane monooxygenase and methane monooxygenases are discussed.

Synthesis and characterization of a new RXR agonist based on the 6-tert-butyl-1,1-dimethylindanyl structure

A new ligand for RXR is described, which is based on a 6-tert-butyl-1,1-dimethylindanyl skeleton as bioisostere of the hydrophobic retinoid region. The Stille cross-coupling reaction allowed the attachment of the polyene side chain to the indanyl ring. Docking studies were carried out to explain the RXR binding profile of this analogue.

The role of electrostatic interactions in governing anesthetic action on the torpedo nicotinic acetylcholine receptor

Isoflurane and normal alkanols reduce the apparent agonist dissociation constant (Kd) of the nicotinic acetylcholine receptor (nAChR) at clinically relevant concentrations, whereas cyclopropane and butane do not. This suggests that electrostatic (hydrogen bonding and/or dipolar) interactions modulate anesthetic potency in this model receptor system. To further define the nature of these interactions, we quantified the potencies with which a heterologous group of general anesthetics reduces the nAChR's apparent Kd for acetylcholine. We assessed the importance that an anesthetic's molecular volume, ability to donate a hydrogen bond (hydrogen bond acidity), ability to accept a hydrogen bond (hydrogen bond basicity), and dipole moment play in determining aqueous potency. We found that aqueous anesthetic potency increases with molecular volume and decreases with hydrogen bond basicity but is unaffected by dipole moment and hydrogen bond acidity. These results suggest that anesthetics reduce the apparent agonist Kd of the nAChR by binding to a site that has a dipolarity and ability to accept hydrogen bonds that are similar to those of water, but a hydrogen bond-donating capacity that is less.

IMPLICATIONS

Anesthetics representing a wide range of chemical classes reduce the apparent agonist dissociation constant of the Torpedo nicotinic acetylcholine receptor with aqueous potencies that are governed by their molecular volumes and hydrogen bond basicities. However, neither their hydrogen bond acidities nor dipole moments influence aqueous potency.

Antagonists of the human CCR5 receptor as anti-HIV-1 agents. Part 3: a proposed pharmacophore model for 1-[N-(methyl)-N-(phenylsulfonyl)amino]-2-(phenyl)-4-[4-(substituted)piperidin-1-yl]butanes

Structure-activity relationship studies directed toward the optimization of (2S)-2-(3-chlorophenyl)-1-[N-(methyl)-N-(phenylsulfonyl)amino]-4-[4-(substituted)piperidin-1-yl]butanes as CCR5 antagonists resulted in the synthesis of the spiro-indanone derivative 8c (IC50=5 nM). These and previous results are summarized in a proposed pharmacophore model for this class of CCR5 antagonist.

Antagonists of the human CCR5 receptor as anti-HIV-1 agents. Part 4: synthesis and structure-activity relationships for 1-[N-(methyl)-N-(phenylsulfonyl)amino]-2-(phenyl)-4-(4-(N-(alkyl)-N-(benzyloxycarbonyl)amino)piperidin-1-yl)butanes

(2S)-2-(3-Chlorophenyl)-1-[N-(methyl)-N-(phenylsulfonyl)amino]-4-[spiro(2,3-dihydrobenzthiophene-3,4'-piperidin-1'-yl)]butane S-oxide (1b) has been identified as a potent CCR5 antagonist having an IC50=10 nM. Herein, structure-activity relationship studies of non-spiro piperidines are described, which led to the discovery of 4-(N-(alkyl)-N-(benzyloxycarbonyl)amino)piperidine derivatives (3-5) as potent CCR5 antagonists.

Inflammatory macrophage nuclear factor-kappaB and proteasome activity are inhibited following exposure to inhaled isobutyl nitrite

A history of abuse of nitrite inhalants has been correlated with HIV seropositivity and Kaposi's sarcoma. A series of 14 daily, 45-min exposures of mice to 900-ppm isobutyl nitrite in an inhalation chamber reduced the number of peritoneal exudate macrophages (PEM) by 35% and the number of resident peritoneal macrophages (RPM) by 18%. Although the tumoricidal activity of RPM was not affected by the inhalant, the cytotoxicity of PEM was reduced by 26%. The induction of nitric oxide (NO) and the inducible NO synthase (iNOS) protein in PEM were inhibited by the inhalant to a similar extent. Inhibition of NF-kappaB activation in PEM from mice exposed to the inhalant corresponded to reduced degradation of the NF-kappaB inhibitor, IkappaB alpha. Proteasome-associated, enzymatic activity was compromised in PEM from inhalant-exposed mice, suggesting that inhaled isobutyl nitrite compromised macrophage, tumoricidal activity by inhibiting proteasomal degradation of the NF-kappaB inhibitor, IkappaB alpha.