The Cyclic Imine Core Common to the Marine Macrocyclic Toxins Is Sufficient to Dictate Nicotinic Acetylcholine Receptor Antagonism

Macrocyclic imine phycotoxins are an emerging class of chemical compounds associated with harmful algal blooms and shellfish toxicity. Earlier binding and electrophysiology experiments on nAChR subtypes and their soluble AChBP surrogates evidenced common trends for substantial antagonism, binding affinities, and receptor-subtype selectivity. Earlier, complementary crystal structures of AChBP complexes showed that common determinants within the binding nest at each subunit interface confer high-affinity toxin binding, while distinctive determinants from the flexible loop C, and either capping the nest or extending toward peripheral subsites, dictate broad versus narrow receptor subtype selectivity. From these data, small spiroimine enantiomers mimicking the functional core motif of phycotoxins were chemically synthesized and characterized. Voltage-clamp analyses involving three nAChR subtypes revealed preserved antagonism for both enantiomers, despite lower subtype specificity and binding affinities associated with faster reversibility compared with their macrocyclic relatives. Binding and structural analyses involving two AChBPs pointed to modest affinities and positional variability of the spiroimines, along with a range of AChBP loop-C conformations denoting a prevalence of antagonistic properties. These data highlight the major contribution of the spiroimine core to binding within the nAChR nest and confirm the need for an extended interaction network as established by the macrocyclic toxins to define high affinities and marked subtype specificity. This study identifies a minimal set of functional pharmacophores and binding determinants as templates for designing new antagonists targeting disease-associated nAChR subtypes.

In-silico molecular modelling studies of some camphor imine based compounds as anti-influenza A (H1N1) pdm09 virus agents

The advent of influenza A (H1N1) drug-resistant strains led to the search quest for more potent inhibitors of the influenza A virus, especially in this devastating COVID-19 pandemic era. Hence, the present research utilized some molecular modelling strategies to unveil new camphor imine-based compounds as anti-influenza A (H1N1) pdm09 agents. The 2D-QSAR results revealed GFA-MLR (R2train = 0.9158, Q2=0.8475) and GFA-ANN (R2train = 0.9264, Q2=0.9238) models for the anti-influenza A (H1N1) pdm09 activity prediction which have passed the QSAR model acceptability thresholds. The results from the 3D-QSAR studies also revealed CoMFA (R2train =0.977, Q2=0.509) and CoMSIA_S (R2train =0.976, Q2=0.527) models for activity predictions. Based on the notable information derived from the 2D-QSAR, 3D-QSAR, and docking analysis, ten (10) new camphor imine-based compounds (22a-22j) were designed using the most active compound 22 as the template. Furthermore, the high predicted activity and binding scores of compound 22j were further justified by the high reactive sites shown in the electrostatic potential maps and other quantum chemical calculations. The MD simulation of 22j in the active site of the influenza hemagglutinin (HA) receptor confirmed the dynamic stability of the complex. Moreover, the appraisals of drug-likeness and ADMET properties of the proposed compounds showed zero violation of Lipinski's criteria with good pharmacokinetic profiles. Hence, the outcomes in this work recommend further in-depth in vivo and in-vitro investigations to validate these theoretical findings.Communicated by Ramaswamy H. Sarma.

Novel orexin receptor agonists based on arene- or pyridine-fused 1,3-dihydro-2H-imidazole-2-imines

A structurally novel class of benzo- or pyrido-fused 1,3-dihydro-2H-imidazole-2-imines was designed and evaluated in an inositol phosphate accumulation assay for Gq signaling to measure agonistic activation of the orexin receptor type 2 (OX2R). These compounds were synthesized in 4-9 steps overall from readily available starting materials. Analogs that contain a stereogenic methyl or cyclopropyl substituent at the benzylic center, and a correctly configured alkyl ether, alkoxyalkyl ether, cyanoalkyl ether, or α-hydroxyacetamido substituted homobenzylic sidechain were identified as the most potent activators of OX2R coupled Gq signaling. Our results also indicate that agonistic activity was stereospecific at both the benzylic and homobenzylic stereogenic centra. We identified methoxyethoxy-substituted pyrido-fused dihydroimidazolimine analog 63c containing a stereogenic benzylic methyl group was the most potent agonist, registering a respectable EC50 of 339 nM and a maximal response (Emax) of 96 % in this assay. In vivo pharmacokinetic analysis indicated good brain exposure for several analogs. Our combined results provide important information towards a structurally novel class of orexin receptor agonists distinct from current chemotypes.

Synthesis of portimines reveals the basis of their anti-cancer activity

Marine-derived cyclic imine toxins, portimine A and portimine B, have attracted attention because of their chemical structure and notable anti-cancer therapeutic potential1-4. However, access to large quantities of these toxins is currently not feasible, and the molecular mechanism underlying their potent activity remains unknown until now. To address this, a scalable and concise synthesis of portimines is presented, which benefits from the logic used in the two-phase terpenoid synthesis5,6 along with other tactics such as exploiting ring-chain tautomerization and skeletal reorganization to minimize protecting group chemistry through self-protection. Notably, this total synthesis enabled a structural reassignment of portimine B and an in-depth functional evaluation of portimine A, revealing that it induces apoptosis selectively in human cancer cell lines with high potency and is efficacious in vivo in tumour-clearance models. Finally, practical access to the portimines and their analogues simplified the development of photoaffinity analogues, which were used in chemical proteomic experiments to identify a primary target of portimine A as the 60S ribosomal export protein NMD3.

Emerging phycotoxins in the Chilean coast: First localized detection of the neurotoxic cyclic imine Pinnatoxin-G in shellfish banks

Pinnatoxins (PnTXs) produced by the cosmopolitan dinoflagellate Vulcanodinium rugosum are highly potent cyclic imines that represent a risk for seafood consumers, artisanal fisheries, and the local aquaculture industry. Among the eight known PnTXs, pinnatoxin-G (PnTX-G) is the most frequent toxin analog detected in shellfish. Despite PnTX-G is still not internationally regulated, the French Agency for Food, Environmental and Occupational Health and Safety established that a risk for human consumers may exist when the accumulation of PnTX-G in shellfish exceeds 23 μg kg^-1. This study reports the first detection of these fast-acting lipophilic toxins in localized shellfish banks (Mytilus chilensis) from the Chilean coast. Among 32 sentinel sampling stations monthly monitored for phytotoxins detection and quantification between 2021 and 2022 along the southern Chilean coast (from 36°25' S to 54°57'S), PnTx-G was only detected in shellfish from the southernmost region of Magallanes in concentrations that ranged between 15 and 100 μg kg^-1, highlighting the binational (Chile/Argentina) Beagle Channel as a 'hotspot'. As Chile is one of the major mussel producers worldwide, this result raises concern about the potential adverse effect of PnTXs for human health and point to the need of governmental actions for an enhanced monitoring of these emerging toxins. To date, the production of PnTXs has not yet been associated with any microalgae species in Chilean waters.

Analgesic Action of Acetaminophen via Kv7 Channels

The mechanism of acetaminophen (APAP) analgesia is at least partially unknown. Previously, we showed that the APAP metabolite N-acetyl-p-benzoquinone imine (NAPQI) activated Kv7 channels in neurons in vitro, and this activation of Kv7 channels dampened neuronal firing. Here, the effect of the Kv7 channel blocker XE991 on APAP-induced analgesia was investigated in vivo. APAP had no effect on naive animals. Induction of inflammation with λ-carrageenan lowered mechanical and thermal thresholds. Systemic treatment with APAP reduced mechanical hyperalgesia, and co-application of XE991 reduced APAP's analgesic effect on mechanical pain. In a second experiment, the analgesic effect of systemic APAP was not antagonized by intrathecal XE991 application. Analysis of liver samples revealed APAP and glutathione-coupled APAP indicative of metabolization. However, there were no relevant levels of these metabolites in cerebrospinal fluid, suggesting no relevant APAP metabolite formation in the CNS. In summary, the results support an analgesic action of APAP by activating Kv7 channels at a peripheral site through formation of the metabolite NAPQI.

The Effects of Quinone Imine, a New Potent Nitrification Inhibitor, Dicyandiamide, and Nitrapyrin on Target and Off-Target Soil Microbiota

Dicyandiamide (DCD) and nitrapyrin (NP) are nitrification inhibitors (NIs) used in agriculture for over 40 years. Recently, ethoxyquin (EQ) was proposed as a novel potential NI, acting through its derivative quinone imine (QI). Still, the specific activity of these NIs on the different groups of ammonia-oxidizing microorganisms (AOM), and mostly their effects on other soil microbiota remain unknown. We determined the impact of QI, and comparatively of DCD and NP, applied at two doses (regular versus high), on the function, diversity, and dynamics of target (AOM), functionally associated (nitrite-oxidizing bacteria-NOB), and off-target prokaryotic and fungal communities in two soils mainly differing in pH (5.4 versus 7.9). QI was equally effective to DCD but more effective than NP in inhibiting nitrification in the acidic soil, while in the alkaline soil QI was less efficient than DCD and NP. This was attributed to the higher activity of QI toward AOA prevailing in the acidic soil. All NIs induced significant effects on the composition of the AOB community in both soils, unlike AOA, which were less responsive. Beyond on-target effects, we noted an inhibitory effect of all NIs on the abundance of NOB in the alkaline soil, with Nitrobacter being more sensitive than Nitrospira. QI, unlike the other NIs, induced significant changes in the composition of the bacterial and fungal communities in both soils. Our findings have serious implications for the efficiency and future use of NIs on agriculture and provide unprecedented evidence for the potential off-target effects of NIs on soil microbiota. IMPORTANCE NIs could improve N use efficiency and decelerate N cycling. Still, we know little about their activity on the distinct AOM groups and about their effects on off-target soil microorganisms. Here, we studied the behavior of a new potent NI, QI, compared to established NIs. We show that (i) the variable efficacy of NIs across soils with different pH reflects differences in the inherent specific activity of the NIs to AOA and AOB; (ii) beyond AOM, NIs exhibit negative effects on other nitrifiers, like NOB; (iii) QI was the sole NI that significantly affected prokaryotic and fungal diversity. Our findings (i) highlight the need for novel NI strategies that consider the variable sensitivity of AOM groups to the different NIs (ii) identify QI as a potent AOA inhibitor, and (iii) stress the need for monitoring NIs' impact on off-target soil microorganisms to ensure sustainable N fertilizers use and soil ecosystem functioning.

Fabrication, DFT Calculation, and Molecular Docking of Two Fe(III) Imine Chelates as Anti-COVID-19 and Pharmaceutical Drug Candidate

Two tetradentate dibasic chelating Schiff base iron (III) chelates were prepared from the reaction of 2,2′-((1E,1′E)-(1,2-phenylenebis(azanylylidene))bis(methanylylidene))bis(4-bromophenol) (PDBS) and 2,2′-((1E,1′E)-((4-chloro-1,2-phenylene)bis(azanylylidene))-bis(methanylylidene))bis(4-bromophenol) (CPBS) with Fe³⁺ ions. The prepared complexes were fully characterized with spectral and physicochemical tools such as IR, NMR, CHN analysis, TGA, UV-visible spectra, and magnetic moment measurements. Moreover, geometry optimizations for the synthesized ligands and complexes were conducted using the Gaussian09 program through the DFT approach, to find the best structures and key parameters. The prepared compounds were tested as antimicrobial agents against selected strains of bacteria and fungi. The results suggests that the CPBSFe complex has the highest activity, which is close to the reference. An MTT assay was used to screen the newly synthesized compounds against a variety of cell lines, including colon cancer cells, hepatic cellular carcinoma cells, and breast carcinoma cells. The results are expressed by IC50 value, in which the 48 µg/mL value of the CPBSFe complex indicates its success as a potential anticancer agent. The antioxidant behavior of the two imine chelates was studied by DPPH assay. All the tested imine complexes show potent antioxidant activity compared to the standard Vitamin C. Furthermore, the in vitro assay and the mechanism of binding and interaction efficiency of the tested samples with the receptor of COVID-19 core protease viral protein (PDB ID: 6lu7) and the receptor of Gram-negative bacteria (Escherichia coli, PDB ID: 1fj4) were investigated using molecular docking experiments.

Artificial intelligence-based identification of octenidine as a Bcl-xL inhibitor

Apoptosis plays an essential role in maintaining cellular homeostasis and preventing cancer progression. Bcl-xL, an anti-apoptotic protein, is an important modulator of the mitochondrial apoptosis pathway and is a promising target for anticancer therapy. In this study, we identified octenidine as a novel Bcl-xL inhibitor through structural feature-based deep learning and molecular docking from a library of approved drugs. The NMR experiments demonstrated that octenidine binds to the Bcl-2 homology 3 (BH3) domain-binding hydrophobic region that consists of the BH1, BH2, and BH3 domains in Bcl-xL. A structural model of the Bcl-xL/octenidine complex revealed that octenidine binds to Bcl-xL in a similar manner to that of the well-known Bcl-2 family protein antagonist ABT-737. Using the NanoBiT protein-protein interaction system, we confirmed that the interaction between Bcl-xL and Bak-BH3 domains within cells was inhibited by octenidine. Furthermore, octenidine inhibited the proliferation of MCF-7 breast and H1299 lung cancer cells by promoting apoptosis. Taken together, our results shed light on a novel mechanism in which octenidine directly targets anti-apoptotic Bcl-xL to trigger mitochondrial apoptosis in cancer cells.

Investigation of the Effects and Mechanisms of Anticancer Action of a Ru(II)-Arene Iminophosphorane Compound in Triple Negative Breast Cancer Cells

Triple negative breast cancer (TNBC) is one of the breast cancers with poorer prognosis and survival rates. TNBC has a disproportionally high incidence and mortality in women of African descent. We report on the evaluation of Ru-IM (1), a water-soluble organometallic ruthenium compound, in TNBC cell lines derived from patients of European (MDA-MB-231) and African (HCC-1806) ancestry (including IC50 values, cellular and organelle uptake, cell death pathways, cell cycle, effects on migration, invasion, and angiogenesis, a preliminary proteomic analysis, and an NCI 60 cell-line panel screen). 1 was previously found highly efficacious in MDA-MB-231 cells and xenografts, with little systemic toxicity and preferential accumulation in the tumor. We observe a similar profile for this compound in the two cell lines studied, which includes high cytotoxicity, apoptotic behavior and potential antimetastatic and antiangiogenic properties. Cytokine M-CSF, involved in the PI3/AKT pathway, shows protein expression inhibition with exposure to 1. We also demonstrate a p53 independent mechanism of action.

Synthesis, In Vitro, and In Silico Analysis of the Antioxidative Activity of Dapsone Imine Derivatives

Dapsone (DDS) is an antibacterial drug with well-known antioxidant properties. However, the antioxidant behavior of its derivatives has not been well explored. In the present work, the antioxidant activity of 10 dapsone derivatives 4-substituted was determined by an evaluation in two in vitro models (DPPH radical scavenging assay and ferric reducing antioxidant power). These imine derivatives 1-10 were obtained through condensation between DDS and the corresponding aromatic aldehydes 4-substuited. Three derivatives presented better results than DDS in the determination of DPPH (2, 9, and 10). Likewise, we have three compounds with better reducing activity than dapsone (4, 9, and 10). In order to be more insight, the redox process, a conceptual DFT analysis was carried out. Molecular descriptors such as electronic distribution, the total charge accepting/donating capacity (I/A), and the partial charge accepting/donating capacity (ω⁺/ω^-) were calculated to analyze the relative donor-acceptor capacity through employing a donor acceptor map (DAM). The DFT calculation allowed us to establish a relationship between GAP_HOMO-LUMO and DAM with the observed antioxidant effects. According to the results, we concluded that compounds 2 and 3 have the lowest R_a values, representing a good antioxidant behavior observed experimentally in DPPH radical capturing. On the other hand, derivatives 4, 9, and 10 display the best reducing capacity activity with the highest ω^- and R_d values. Consequently, we propose these compounds as the best antireductants in our DDS imine derivative series.

Cyclic Imine Pinnatoxin G is Cytotoxic to Cancer Cell Lines via Nicotinic Acetylcholine Receptor-Driven Classical Apoptosis

Pinnatoxin G is a cyclic imine neurotoxin produced by dinoflagellates that has been reported in shellfish. Like other members of the pinnatoxin family, it has been shown to have its effects via antagonism of the nicotinic acetylcholine receptors, with preferential binding to the α7 subunit often upregulated in cancer. Because increased activity of α7 nicotinic acetylcholine receptors contributes to increased growth and resistance to apoptosis, the effect of pinnatoxin G on cancer cell viability was tested. In a panel of six cancer cell lines, all cell types lost viability, but HT29 colon cancer and LN18 and U373 glioma cell lines were more sensitive than MDA-MB-231 breast cancer cells, PC3 prostate cancer cells, and U87 glioma cells, correlating with expression levels of α7, α4, and α9 nicotinic acetylcholine receptors. Some loss of cell viability could be attributed to cell cycle arrest, but significant levels of classical apoptosis were found, characterized by caspase activity, phosphatidylserine exposure, mitochondrial membrane permeability, and fragmented DNA. Intracellular Ca²⁺ levels also dropped immediately upon pinnatoxin G treatment, which may relate to antagonism of nicotinic acetylcholine receptor-mediated Ca²⁺ inflow. In conclusion, pinnatoxin G can decrease cancer cell viability, with both cytostatic and cytotoxic effects.

Synthesis of 1,4-dihydropyrazolo[4,3-b]indoles via intramolecular C(sp2)-N bond formation involving nitrene insertion, DFT study and their anticancer assessment

We herein report a new synthetic route for a series of unreported 1,4-dihydropyrazolo[4,3-b]indoles (6-8) via deoxygenation of o-nitrophenyl-substituted N-aryl pyrazoles and subsequent intramolecular (sp²)-N bond formation under microwave irradiation expedite modified Cadogan condition. This method allows access to NH-free as well as N-substituted fused indoles. DFT study and controlled experiments highlighted the role of nitrene insertion as one of the plausible reaction mechanisms. Furthermore, the target compounds exhibited cytotoxicity at low micromolar concentration against lung (A549), colon (HCT-116), and breast (MDA-MB-231, and MCF-7) cancer cell lines, induced the ROS generation and altered the mitochondrial membrane potential of highly aggressive MDA-MB-231 cells. Further investigations revealed that these compounds were selective Topo I (6h) or Topo II (7a, 7b) inhibitors.

Synthesis, Structure and Cytotoxicity Testing of Novel 7-(4,5-dihydro-1H-imidazol-2-yl)-2-aryl-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-Imine Derivatives

The appropriate 1-arylhydrazinecarbonitriles 1a-c are subjected to the reaction with 2-chloro-4,5-dihydro-1H-imidazole (2), yielding 7-(4,5-dihydro-1H-imidazol-2-yl)-2-aryl-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-imines 3a-c, which are subsequently converted into the corresponding amides 4a-e, 8a-c, sulfonamides 5a-n, 9, ureas 6a-I, and thioureas 7a-d. The structures of the newly prepared derivatives 3a-c, 4a-e, 5a-n, 6a-i, 7a-d, 8a-c, and 9 are confirmed by IR, NMR spectroscopic data, as well as single-crystal X-ray analyses of 5e and 8c. The in vitro cytotoxic potency of these compounds is determined on a panel of human cancer cell lines, and the relationships between structure and antitumor activity are discussed. The most active 4-chloro-N-(2-(4-chlorophenyl)-7-(4,5-dihydro-1H-imidazol-2-yl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)benzamide (4e) and N-(7-(4,5-dihydro-1H-imidazol-2-yl)-2-(p-tolyl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)-[1,1'-biphenyl]-4-sulfonamide (5l) inhibits the growth of the cervical cancer SISO and bladder cancer RT-112 cell lines with IC50 values in the range of 2.38-3.77 μM. Moreover, N-(7-(4,5-dihydro-1H-imidazol-2-yl)-2-phenyl-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)-4-phenoxybenzenesulfonamide (5m) has the best selectivity towards the SISO cell line and induces apoptosis in this cell line.

Gymnodimine A and 13-desMethyl Spirolide C Alter Intracellular Calcium Levels via Acetylcholine Receptors

Gymnodimines and spirolides are cyclic imine phycotoxins and known antagonists of nicotinic acetylcholine receptors (nAChRs). We investigated the effect of gymnodimine A (GYM A) and 13-desmethyl spirolide C (SPX 1) from Alexandrium ostenfeldii on rat pheochromocytoma (PC12) cells by monitoring intracellular calcium levels ([Ca]_i). Using whole cells, the presence of 0.5 µM of GYM A or SPX 1 induced an increase in [Ca]_i mediated by acetylcholine receptors (AChRs) and inhibited further activation of AChRs by acetylcholine (ACh). To differentiate the effects of GYM A or SPX 1, the toxins were applied to cells with pharmacologically isolated nAChRs and muscarinic AChRs (mAChRs) as mediated by the addition of atropine and tubocurarine, respectively. GYM A and SPX 1 activated nAChRs and inhibited the further activation of nAChRs by ACh, indicating that both toxins mimicked the activity of ACh. Regarding mAChRs, a differential response was observed between the two toxins. Only GYM A activated mAChRs, resulting in elevated [Ca]_i, but both toxins prevented a subsequent activation by ACh. The absence of the triketal ring system in GYM A may provide the basis for a selective activation of mAChRs. GYM A and SPX 1 induced no changes in [Ca]_i when nAChRs and mAChRs were inhibited simultaneously, indicating that both toxins target AChRs.

Novel enantiopure isoxazolidine and C-alkyl imine oxide derivatives as potential hypoglycemic agents: Design, synthesis, dual inhibitors of α-amylase and α-glucosidase, ADMET and molecular docking study

In an effort to explore a new class of antidiabetic inhibitors, a new series of isoxazolidine and C-alkyl imine oxide derivatives scaffolds were designed, synthesized and fully characterized. The newly synthesized analogues were evaluated for their human pancreatic α-amylase (HPA) and human lysosomal acid-α-glucosidase (HLAG) inhibitory activities and have shown a higher potency than acarbose. The compounds 7b (23.1 ± 1.1 μM) and 7a (36.3 ± 1.6 μM) were identified as the potent HPA and HLAG inhibitors with inhibitory effect up to 9 and 21-fold higher than acarbose, respectively. Antihyperglycemic activity results were supported by molecular docking approach of the most potent compounds 7b and 7a showing stronger interactions with the active site of HPA and HLAG as well as by in silico absorption, distribution, metabolism, excretion and toxicity (ADMET) profile suggesting their satisfactory oral druglikeness without toxic effect. Therefore, it can be concluded that both 7b and 7a can be used as effective lead molecules for the development of HPA and HLAG inhibitors for the management of T2DM.

Peroxidasin is essential for endothelial cell survival and growth signaling by sulfilimine crosslink-dependent matrix assembly

Peroxidasin (PXDN) has been reported to crosslink the C-terminal non-collagenous domains of collagen IV (Col IV) by forming covalent sulfilimine bond. Here, we explored the physiological role of PXDN and its mechanism of action in endothelial cell survival and growth. Silencing of PXDN using siRNAs decreased cell proliferation without increase of the number of detached cells and decreased cell viability under serum-starved condition with increased fragmented nuclei and caspase 3/7 activity. Conditioned medium (CM) containing wild-type PXDN restored the proliferation of PXDN-depleted cells, but CM containing mutant PXDN with deletion of either N-terminal extracellular matrix (ECM) motifs or peroxidase domain failed to restore PXDN function. Accordingly, anti-PXDN antibody [raised against IgC2 (3-4) subdomain within ECM motifs] and peroxidase inhibitor phloroglucinol prevented the rescue of the PXDN-depleted cells by PXDN-containing CM. PXDN depletion resulted in loss of sulfilimine crosslinks, and decreased dense fibrillar network assembly of not only Col IV, but also fibronectin and laminin like in Col IV knockdown. Exogenous PXDN-containing CM restored ECM assembly as well as proliferation of PXDN-depleted cells. Accordingly, purified recombinant PXDN protein restored the proliferation and ECM assembly, and prevented cell death of the PXDN-depleted cells. PXDN depletion also showed reduced growth factors-induced phosphorylation of FAK and ERK1/2. In addition, siPXDN-transfected cell-derived matrix failed to provide full ECM-mediated activation of FAK and ERK1/2. These results indicate that both the ECM motifs and peroxidase activity are essential for the cellular function of PXDN and that PXDN is crucial for ECM assembly for survival and growth signaling.

β-Diketonate versus β-Ketoiminate: The Importance of a Ferrocenyl Moiety in Improving the Anticancer Potency

Herein we present a library of fully characterized β-diketonate and β-ketoiminate compounds that are functionalized with a ferrocenyl moiety. Their cytotoxic potential has been determined by screening against human breast adenocarcinomas (MCF-7 and MDA-MB-231), human colorectal carcinoma p53 wild type (HCT116 p53+/+ ) and normal human prostate (PNT2) cell lines. The ferrocenyl β-diketonate compounds are more than 18 times more cytotoxic than the ferrocenyl β-ketoiminate analogues. Against MCF-7, compounds functionalized at the meta position are up to nine times more cytotoxic than when functionalized at the para position. The ferrocenyl β-diketonate compounds have increased selectivity towards MCF-7 and MDA-MB-231, with several complexes having selectivity index (SI) values that are more than nine times (MCF-7) and more than six times (MDA-MB-231) that of carboplatin. The stability of these compounds in dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) has been assessed by NMR spectroscopy and mass spectrometry studies, and the compounds show no oxidation of the iron center from FeII to FeIII . Cytotoxicity screening was performed in both DMSO and DMF, with no significant differences observedin their potency.

A screening of the MMV Pathogen Box® reveals new potential antifungal drugs against the etiologic agents of chromoblastomycosis

Chromoblastomycosis (CBM) is a chronic subcutaneous mycosis caused by traumatic implantation of many species of black fungi. Due to the refractoriness of some cases and common recurrence of CBM, a more effective and less time-consuming treatment is mandatory. The aim of this study was to identify compounds with in vitro antifungal activity in the Pathogen Box® compound collection against different CBM agents. Synergism of these compounds with drugs currently used to treat CBM was also assessed. An initial screening of the drugs present in this collection at 1 μM was performed with a Fonsecaea pedrosoi clinical strain according to the EUCAST protocol. The compounds with activity against this fungus were also tested against other seven etiologic agents of CBM (Cladophialophora carrionii, Phialophora verrucosa, Exophiala jeanselmei, Exophiala dermatitidis, Fonsecaea monophora, Fonsecaea nubica, and Rhinocladiella similis) at concentrations ranging from 0.039 to 10 μM. The analysis of potential synergism of these compounds with itraconazole and terbinafine was performed by the checkerboard method. Eight compounds inhibited more than 60% of the F. pedrosoi growth: difenoconazole, bitertanol, iodoquinol, azoxystrobin, MMV688179, MMV021013, trifloxystrobin, and auranofin. Iodoquinol produced the lowest MIC values (1.25-2.5 μM) and MMV688179 showed MICs that were higher than all compounds tested (5 - >10 μM). When auranofin and itraconazole were tested in combination, a synergistic interaction (FICI = 0.37) was observed against the C. carrionii isolate. Toxicity analysis revealed that MMV021013 showed high selectivity indices (SI ≥ 10) against the fungi tested. In summary, auranofin, iodoquinol, and MMV021013 were identified as promising compounds to be tested in CBM models of infection.

Effect of Pharmacological Inhibition of the Catalytic Activity of Phosphatases of Regenerating Liver in Early T Cell Receptor Signaling Dynamics and IL-2 Production

We have previously shown the delivery of phosphatase of regenerating liver-1 (PRL-1) to the immunological synapse (IS) and proposed a regulatory role of the catalytic activity of PRLs (PRL-1, PRL-2 and PRL-3) in antigen-induced IL-2 production. Nonetheless, the expression in T cells and delivery to the IS of the highly homologous PRL-3, as well as the role of the catalytic activity of PRLs in antigen-induced early signaling, has not been investigated. Here, the expression of PRL-3 protein was detected in primary CD4 T cells and in the CD4 T cell line Jurkat (JK), in which an overexpressed GFP-PRL-3 fluorescent fusion protein trafficked through the endosomal recycling compartment and co-localized with PLCγ1 signaling sites at the IS. Pharmacological inhibition was used to compare the role of the catalytic activity of PRLs in antigen-induced early signaling and late IL-2 production. Although the phosphatase activity of PRLs was not critical for early signaling triggered by antigen, it seemed to regulate signaling dynamics and was necessary for proper IL-2 production. We propose that enzymatic activity of PRLs has a higher significance for cytokine production than for early signaling at the IS. However, further research will be necessary to deeply understand the regulatory role of PRLs during lymphocyte activation and effector function.

Poly(2-oxazoline)s with a 2,2'-Iminodiacetate End Group Inhibit and Stabilize Laccase

Poly(2-oxazoline)s (POxs) with 2,2'-iminodiacetate (IDA) end groups were investigated as inhibitors for laccase. The polymers with the IDA end groups are reversible, competitive inhibitors for this enzyme. The IC50 values were found to be in a range of 1-3 mm. Compared with IDA alone, the activity was increased by a factor of more than 30; thus indicating that attaching a polymer chain to an inhibitor can already improve the activity of the former. The enzyme activity drops to practically zero upon increasing the concentration of the most active telechelic inhibitor, IDA-PEtOx30 -IDA (PEtOx: poly(2-ethyl-2-oxazoline)), from 5 to 8 mm. This unusual behavior was investigated by means of dynamic light scattering, which showed specific aggregation above 5 mm. Furthermore, the laccase could be stabilized in the presence of POx-IDA, upon addition at a concentration of 20 mm and higher. Whereas laccase becomes completely inactive at room temperature after one week, the stabilized laccase is fully active for at least a month in aqueous solution.

The effects of TPL-PEI-CyD on suppressing performance of MCF-7 stem cells

Triptolide, an ingredient of Tripterygium wilfordii, has been demonstrated to possess many biological activities such as immunomodulatory, antitumor activity in experiment. The purpose of this study was to survey the toxicity of TPL-PEI-CyD on renal cells and its effects on breast carcinoma stem cells. The cytotoxicity of TPL-PEI-CyD and TPL on HK-2 was comparatively assessed by CCK-8. After incubation and culturing with TGF-β1, the MCF-7 cells were assessed by flow cytometry for the proportion of CD₄₄^+> CD₂₄- cells; then the CD₄₄>^+> CD₂₄- cells were sorted by immunomagnetic beads as MCF-7 stem cells. To assess the effect of TPL-PEI-CyD on MCF-7 stem cells, Western Blot was used to detect the expression of Oct-4 and ALDHl in MCF-7 stem cells after being dosed with TPL- PEI-CyD. Results showed that, compared with TPL, the toxicity of TPL-PEI-CyD on HK-2 cells was significantly reduced (P<0.05). Breast carcinoma stem cells can be enriched by TGF-β1 and isolated from MCF-7 cells by immunomagnetic sorting. TPL- PEI-CyD can even more significantly suppress the expression of Oct-4 and ALDHA1 in MCF-7 stem cells than TPL (P<0.05). In conclusion, after coupling TPL and PEI-CyD, TPL-PEI-CyD showed characteristics of effective suppression to breast carcinoma stem cell and decrease of cytotoxicity. It presented the unique effect of traditional Chinese medicine as an efficient and low toxic drug carrier complex for breast carcinoma treatment.

Design, synthesis and antifungal activity of (E)-3-acyl-5-(methoxyimino)-1,5-dihydrobenzo[e][1,2]oxazepin-4(3H)-one analogues

Nitrogen- or oxygen-containing organic compounds which have significant antifungal activity, twenty one novel nitrogen or oxygen-containing (E)-3-acyl-5-(methoxyimino)-1,5-dihydrobenzo[e][1,2]oxazepin-4(3H)-one analogues were designed and synthesized, and their structures were confirmed by ¹H NMR, ¹³C NMR and HRMS. Preliminary bioassay showed that most of them exhibited certain-to-good antifungal activity. Compounds 5k-2, 5n, 5p and 5r exhibited over 80% inhibitory rate against Sclerotinia sclerotiorum at 50 μg/mL, and 5r exhibited good antifungal activity against S. sclerotiorum with EC₅₀ of 7.21 μg/mL. Compounds 5a and 5r also showed over 90% inhibition against Botrytis cinerea. In particular, 5r showed significant higher activity with the lowest EC₅₀ of 7.92 μg/mL than the positive control trifloxystrobin (21.96 μg/mL) and azoxystrobin (9.43 μg/mL). Providing a practical method for the synthesis of new scaffolds 1,2-Benzoxazepinone and systematically investigate their antifungal activity.

Next-Generation Cell-Active Inhibitors of the Undrugged Oncogenic PTP4A3 Phosphatase

Oncogenic protein tyrosine phosphatases (PTPs) are overexpressed in numerous human cancers but they have been challenging pharmacological targets. The emblematic oncogenic PTP4A tyrosine phosphatase family regulates many fundamental malignant processes. 7-Imino-2-phenylthieno[3,2-c]pyridine-4,6(5H,7H)-dione (JMS-053) is a novel, potent, and selective PTP4A inhibitor but its mechanism of action has not been fully elucidated, nor has the chemotype been fully investigated. Because tyrosine phosphatases are notoriously susceptible to oxidation, we interrogated JMS-053 and three newly synthesized analogs with specific attention on the role of oxidation. JMS-053 and its three analogs were potent in vitro PTP4A3 inhibitors, but 7-imino-5-methyl-2-phenylthieno[3,2-c]pyridine-4,6(5H,7H)-dione (NRT-870-59) appeared unique among the thienopyridinediones with respect to its inhibitory specificity for PTP4A3 versus both a PTP4A3 A111S mutant and an oncogenic dual specificity tyrosine phosphatase, CDC25B. Like JMS-053, NRT-870-59 was a reversible PTP4A3 inhibitor. All of the thienopyridinediones retained cytotoxicity against human ovarian and breast cancer cells grown as pathologically relevant three-dimensional spheroids. Inhibition of cancer cell colony formation by NRT-870-59, like JMS-053, required PTP4A3 expression. JMS-053 failed to generate significant detectable reactive oxygen species in vitro or in cancer cells. Mass spectrometry results indicated no disulfide bond formation or oxidation of the catalytic Cys104 after in vitro incubation of PTP4A3 with JMS-053 or NRT-870-59. Gene expression profiling of cancer cells exposed to JMS-053 phenocopied many of the changes seen with the loss of PTP4A3 and did not indicate oxidative stress. These data demonstrate that PTP4A phosphatases can be selectively targeted with small molecules that lack prominent reactive oxygen species generation and encourage further studies of this chemotype. SIGNIFICANCE STATEMENT: Protein tyrosine phosphatases are emerging as important contributors to human cancers. We report on a new class of reversible protein phosphatase small molecule inhibitors that are cytotoxic to human ovarian and breast cancer cells, do not generate significant reactive oxygen species in vitro and in cells, and could be valuable lead molecules for future studies of PTP4A phosphatases.

Discovery and evaluation of Atopaxar hydrobromide, a novel JAK1 and JAK2 inhibitor, selectively induces apoptosis of cancer cells with constitutively activated STAT3

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway plays a vital role in immunity, cell division, cell death and tumor formation. Disrupted JAK-STAT signaling may lead to various diseases, especially cancer and immune disorders. Because of its importance, this signaling pathway has received significant attention from the pharmaceutical and biotechnology industries as a therapeutic target for drug design. However, few JAK or STATs inhibitors have been developed for cancer treatment. We used an in vitro STAT3 luciferase reporter assay to find novel inhibitors that could effectively block the JAK-STAT pathway. In our study, we screened 16,081 drug-like chemicals and found that atopaxar hydrobromide (AHB) is a specific inhibitor of JAK-STAT3 signaling. Our results suggest that AHB not only blocks constitutively activated and cytokine-induced STAT3 phosphorylation but also inhibits JAK1 and JAK2 phosphorylation. Moreover, AHB induces G1 phase cell cycle arrest, which stops cancer cell growth and induces apoptosis. AHB also inhibited tumor cell growth in vivo. In conclusion, AHB is a potential inhibitor that could be developed as a JAK-STAT pathway drug.

The Spirocyclic Imine from a Marine Benthic Dinoflagellate, Portimine, Is a Potent Anti-Human Immunodeficiency Virus Type 1 Therapeutic Lead Compound

In this study, we aimed to find chemicals from lower sea animals with defensive effects against human immunodeficiency virus type 1 (HIV-1). A library of marine natural products consisting of 80 compounds was screened for activity against HIV-1 infection using a luciferase-encoding HIV-1 vector. We identified five compounds that decreased luciferase activity in the vector-inoculated cells. In particular, portimine, isolated from the benthic dinoflagellate Vulcanodinium rugosum, exhibited significant anti-HIV-1 activity. Portimine inhibited viral infection with an 50% inhibitory concentration (IC₅₀) value of 4.1 nM and had no cytotoxic effect on the host cells at concentrations less than 200 nM. Portimine also inhibited vesicular stomatitis virus glycoprotein (VSV-G)-pseudotyped HIV-1 vector infection. This result suggested that portimine mainly targeted HIV-1 Gag or Pol protein. To analyse which replication steps portimine affects, luciferase sequences were amplified by semi-quantitative PCR in total DNA. This analysis revealed that portimine inhibits HIV-1 vector infection before or at the reverse transcription step. Portimine has also been shown to have a direct effect on reverse transcriptase using an in vitro reverse transcriptase assay. Portimine efficiently inhibited HIV-1 replication and is a potent lead compound for developing novel therapeutic drugs against HIV-1-induced diseases.

Kabirimine, a New Cyclic Imine from an Okinawan Dinoflagellate

On our quest for new bioactive molecules from marine sources, two cyclic imines (1, 2) were isolated from a dinoflagellate extract, inhibiting the growth of the respiratory syncytial virus (RSV). Compound 1 was identified as a known molecule portimine, while 2 was elucidated to be a new cyclic imine, named kabirimine. The absolute stereochemistry of 1 was determined by crystallographic work and chiral derivatization, whereas the structure of 2 was elucidated by means of spectroscopic analysis and computational study on all the possible isomers. Compound 1 showed potent cytotoxicity (CC50 < 0.097 µM) against HEp2 cells, while 2 exhibited moderate antiviral activity against RSV with IC50 = 4.20 µM (95% CI 3.31-5.33).

Imine Bond- and Coordinate Bond-Linked pH-Sensitive Cisplatin Complex Nanoparticles for Active Targeting to Tumor Cells

Aldehyde hyaluronic acid-cisplatin (A-HA-CDDP) complex nanoparticles were readily prepared, and CDDP was stably loaded into the core of the NPs through imine bond and coordinate bond linkages. The results show that the NPs were prepared successfully by a chemical complexation reaction rather than by physical mixing. Compared to many CDDP and HA complex nanoparticles evaluated in other studies, A-HA-CDDP NPs with imine and coordinate bonds between the A-HA and CDDP displayed better sustained release behavior and pH sensitivity. Therefore, the acidic tumor environment could accelerate the release of CDDP from the NPs. MTT and AO/EB staining assays showed that A-HA-CDDP NPs had comparable cell inhibition with CDDP in HeLa cells as well as little toxicity to NIH3T3 cells. This result indicates that the chemical reaction between A-HA and CDDP had little effect on the antitumor activity of CDDP and that the NPs actively targeted CD44-rich tumor cells. Both a hemolysis test and a protein adsorption assay demonstrated that A-HA-CDDP NPs had good biocompatibility and blood circulation in vivo. Therefore, the NPs have the potential to be used for targeted CDDP delivery in vivo. A subsequent publication will describe the circulation, targeting and tumor inhibition experiments of these NPs in vivo.

The paracetamol metabolite N-acetylp-benzoquinone imine reduces excitability in first- and second-order neurons of the pain pathway through actions on KV7 channels

Paracetamol (acetaminophen, APAP) is one of the most frequently used analgesic agents worldwide. It is generally preferred over nonsteroidal anti-inflammatory drugs because it does not cause typical adverse effects resulting from the inhibition of cyclooxygenases, such as gastric ulcers. Nevertheless, inhibitory impact on these enzymes is claimed to contribute to paracetamols mechanisms of action which, therefore, remained controversial. Recently, the APAP metabolites N-arachidonoylaminophenol (AM404) and N-acetyl-p-benzoquinone imine (NAPQI) have been detected in the central nervous system after systemic APAP administration and were reported to mediate paracetamol effects. In contrast to nonsteroidal anti-inflammatory drugs that rather support seizure activity, paracetamol provides anticonvulsant actions, and this dampening of neuronal activity may also form the basis for analgesic effects. Here, we reveal that the APAP metabolite NAPQI, but neither the parent compound nor the metabolite AM404, reduces membrane excitability in rat dorsal root ganglion (DRG) and spinal dorsal horn (SDH) neurons. The observed reduction of spike frequencies is accompanied by hyperpolarization in both sets of neurons. In parallel, NAPQI, but neither APAP nor AM404, increases currents through KV7 channels in DRG and SDH neurons, and the impact on neuronal excitability is absent if KV7 channels are blocked. Furthermore, NAPQI can revert the inhibitory action of the inflammatory mediator bradykinin on KV7 channels but does not affect synaptic transmission between DRG and SDH neurons. These results show that the paracetamol metabolite NAPQI dampens excitability of first- and second-order neurons of the pain pathway through an action on KV7 channels.

Electrically Responsive, Nanopatterned Surfaces for Triggered Delivery of Biologically Active Molecules into Cells

Polyelectrolyte multilayers (PEMs) assembled layer-by-layer have emerged as functional polymer films that are both stable and capable of containing drug molecules for controlled release applications. Most of these applications concentrate on sustained release, where the concentration of the released molecules remains rather constant with time. However, high-efficiency delivery requires obtaining high local concentrations at the vicinity of the cells, which is achieved by triggered release. Here, we show that a nanopatterned PEM platform demonstrates superior properties with respect to drug retention and triggered delivery. A chemically modified block copolymer film was used as a template for the selective deposition of poly(ethylene imine) and a charged derivative of the electroactive poly(3,4-ethylenedioxythiophene) together with a drug molecule. This nanopatterned PEM shows the following advantages: (1) high drug loading; (2) enhanced retention of the bioactive molecule; (3) release triggered by an electrochemical stimulus; (4) high efficacy of drug delivery to cells adsorbed on the surface compared to the delivery efficacy of a similar concentration of drug to cells suspended in a solution.

Effective chemical protection against the maize late wilt causal agent, Harpophora maydis, in the field

Late wilt, a disease severely affecting maize fields throughout Israel, is characterized by relatively rapid wilting of maize plants before tasseling and until shortly before maturity. The disease's causal agent is the fungus Harpophora maydis, a soil-borne and seed-borne pathogen, which is currently controlled using reduced sensitivity maize cultivars. In a former study, we showed that Azoxystrobin (AS) injected into a drip irrigation line assigned for each row can suppress H. maydis in the field and that AS seed coating can provide an additional layer of protection. In the present study, we examine a more cost-effective protective treatment using this fungicide with Difenoconazole mixture (AS+DC), or Fluazinam, or Fluopyram and Trifloxystrobin mixture, or Prothioconazole and Tebuconazole mixture in combined treatment of seed coating and a drip irrigation line for two coupling rows. A recently developed Real-Time PCR method revealed that protecting the plants using AS+DC seed coating alone managed to delay pathogen DNA spread in the maize tissues, in the early stages of the growth season (up to the age of 50 days from sowing), but was less effective in protecting the crops later. AS+DC seed coating combined with drip irrigation using AS+DC was the most successful treatment, and in the double-row cultivation, it reduced fungal DNA in the host tissues to near zero levels. This treatment minimized the development of wilt symptoms by 41% and recovered cob yield by a factor of 1.6 (to the level common in healthy fields). Moreover, the yield classified as A class (cob weight of more than 250 g) increased from 58% to 75% in this treatment. This successful treatment against H. maydis in Israel can now be applied in vast areas to protect sensitive maize cultivars against maize late wilt disease.

Manganese toxicity is targeting an early step in the dopamine signal transduction pathway that controls lateral cilia activity in the bivalve mollusc Crassostrea virginica

Manganese is a neurotoxin causing manganism, a Parkinson-like clinical disorder. Manganese has been shown to interfere with dopaminergic neurotransmission, but the neurotoxic mechanism involved is not fully resolved. In the bivalve mollusc Crassostrea virginica also known as the eastern oyster, beating rates of lateral cilia of the gill are controlled by dopaminergic-serotonergic innervation originating from their cerebral and visceral ganglia. Terminal release of dopamine activates D2-like receptors on these gill cells inhibiting adenylyl cyclase and slowing cilia beating rates. In C. virginica, manganese treatment disrupts this dopaminergic innervation of the gill, preventing the normal cilio-inhibitory response of lateral cells to dopamine. In this study an adenylyl cyclase activator (forskolin) and two different inhibitors (MDL-12,330A and SQ 22,536) were used to determine if manganese had any effects on the adenylyl cyclase step of the dopamine D2 receptor signal transduction pathway. The results showed that neither the adenylyl cyclase activator nor the inhibitors were affected by manganese in the control of lateral ciliary activity. This suggests that in C. virginica the mechanism of manganese toxicity on the dopaminergic control of lateral ciliary activity is targeting an early step in the D2R signal transduction pathway, which may involve interference with D2 receptor activation or alternatively some other downstream signaling activity that does not affect adenylyl cyclase.

Phloretin cytoprotection and toxicity

Phloretin (Phl) is a dihydrochalcone flavonoid with significant cytoprotective properties; e.g., free radical trapping, electrophile scavenging. Based on this, it has been suggested that Phl might be useful in the treatment of pathogenic processes and prevention of drug toxicities. Therefore, we determined the ability of Phl to provide route- and dose-dependent hepatoprotection in a mouse model of acetaminophen (APAP) overdose. Intraperitoneal (i.p.) administration of Phl produced a bimodal effect; i.e., the highest dose (2.40 mmol/kg) did not prevent APAP-induced lethality, whereas lower doses (0.2-0.4 mmol/kg) afforded modest hepatoprotection. When given alone, the highest i.p. Phl dose was lethal within 24 h, whereas the lower doses were not toxic. Oral Phl (0.40-2.40 mmol/kg) did not prevent APAP-induced hepatotoxicity. The highest oral dose given alone (2.4 mmol/kg) produced 64% lethality, whereas lower doses were not lethal. This toxicity profile was reflected in a study using APAP-exposed isolated mouse hepatocytes, which showed that the Phl pharmacophores, 1,3,5-trihydroxyacetophenone (PG) and 2',4',6'-trihydroxyacetophenone (THA) where protective. Corroborative cell free studies showed that polyphenol protectants prevented glutathione loss mediated by the APAP metabolite, N-acetyl-p-benzoquinone imine (NAPQI). Thus, in spite of possessing cytoprotective attributes, Phl was generally toxic in our APAP models. These and earlier findings suggest that Phl is not a candidate for drug design. In contrast, we have found that the enol-forming pharmacophores, THA and PG, are potential platforms for pharmacotherapeutic development.

Antifouling activity of portimine, select semisynthetic analogues, and other microalga-derived spirocyclic imines

A range of natural products from marine invertebrates, bacteria and fungi have been assessed as leads for nature-inspired antifouling (AF) biocides, but little attention has been paid to microalgal-derived compounds. This study assessed the AF activity of the spirocyclic imine portimine (1), which is produced by the benthic mat-forming dinoflagellate Vulcanodinium rugosum. Portimine displayed potent AF activity in a panel of four macrofouling bioassays (EC₅₀ 0.06-62.5 ng ml^-1), and this activity was distinct from that of the related compounds gymnodimine-A (2), 13-desmethyl spirolide C (3), and pinnatoxin-F (4). The proposed mechanism of action for portimine is induction of apoptosis, based on the observation that portimine inhibited macrofouling organisms at developmental stages known to involve apoptotic processes. Semisynthetic modification of select portions of the portimine molecule was subsequently undertaken. Observed changes in bioactivity of the resulting semisynthetic analogues of portimine were consistent with portimine's unprecedented 5-membered imine ring structure playing a central role in its AF activity.

Branched Poly(ethylene imine)s as Anti-algal and Anti-cyanobacterial Agents with Selective Flocculation Behavior to Cyanobacteria over Algae

Poly(ethylene imine)s (PEIs) have been widely studied for biomedical applications, including antimicrobial agents against potential human pathogens. The interactions of branched PEIs (B-PEIs) with environmentally relevant microorganisms whose uncontrolled growth in natural or engineered environments causes health, economic, and technical issues in many sectors of water management are studied. B-PEIs are shown to be potent antimicrobials effective in controlling the growth of environmentally relevant algae and cyanobacteria with dual-functionality and selectivity. Not only did they effectively inhibit growth of both algae and cyanobacteria, mostly without causing cell death (static activity), but they also selectively flocculated cyanobacteria over algae. Thus, unmodified B-PEIs provide a cost-effective and chemically facile framework for the further development of effective and selective antimicrobial agents useful for control of growth and separation of algae and cyanobacteria in natural or engineered environments.

Characterization of Protease-Activated Receptor (PAR) ligands: Parmodulins are reversible allosteric inhibitors of PAR1-driven calcium mobilization in endothelial cells

Several classes of ligands for Protease-Activated Receptors (PARs) have shown impressive anti-inflammatory and cytoprotective activities, including PAR2 antagonists and the PAR1-targeting parmodulins. In order to support medicinal chemistry studies with hundreds of compounds and to perform detailed mode-of-action studies, it became important to develop a reliable PAR assay that is operational with endothelial cells, which mediate the cytoprotective effects of interest. We report a detailed protocol for an intracellular calcium mobilization assay with adherent endothelial cells in multiwell plates that was used to study a number of known and new PAR1 and PAR2 ligands, including an alkynylated version of the PAR1 antagonist RWJ-58259 that is suitable for the preparation of tagged or conjugate compounds. Using the cell line EA.hy926, it was necessary to perform media exchanges with automated liquid handling equipment in order to obtain optimal and reproducible antagonist concentration-response curves. The assay is also suitable for study of PAR2 ligands; a peptide antagonist reported by Fairlie was synthesized and found to inhibit PAR2 in a manner consistent with reports using epithelial cells. The assay was used to confirm that vorapaxar acts as an irreversible antagonist of PAR1 in endothelium, and parmodulin 2 (ML161) and the related parmodulin RR-90 were found to inhibit PAR1 reversibly, in a manner consistent with negative allosteric modulation.

Design and application of cationic amphiphilic β-cyclodextrin derivatives as gene delivery vectors

The nano self-assembly profiles of amphiphilic gene delivery vectors could improve the density of local cationic head groups to promote their DNA condensation capability and enhance the interaction between cell membrane and hydrophobic tails, thus increasing cellular uptake and gene transfection. In this paper, two series of cationic amphiphilic β-cyclodextrin (β-CD) derivatives were designed and synthesized by using 6-mono-OTs-β-CD (1) as the precursor to construct amphiphilic gene vectors with different building blocks in a selective and controlled manner. The effect of different type and degree of cationic head groups on transfection and the endocytic mechanism of β-CD derivatives/DNA nanocomplexes were also investigated. The results demonstrated that the designed β-cyclodextrin derivatives were able to compact DNA to form stable nanocomplexes and exhibited low cytotoxicity. Among them, PEI-1 with PEI head group showed enhanced transfection activity, significantly higher than commercially available agent PEI25000 especially in the presence of serum, showing potential application prospects in clinical trials. Moreover, the endocytic uptake mechanism involved in the gene transfection of PEI-1 was mainly through caveolae-mediated endocytosis, which could avoid the lysosomal degradation of loaded gene, and had great importance for improving gene transfection activity.

Orexin receptor agonist Yan 7874 is a weak agonist of orexin/hypocretin receptors and shows orexin receptor-independent cytotoxicity

Two promising lead structures of small molecular orexin receptor agonist have been reported, but without detailed analyses of the pharmacological properties. One of them, 1-(3,4-dichlorophenyl)-2-[2-imino-3-(4-methylbenzyl)-2,3-dihydro-1H-benzo[d]imidazol-1-yl]ethan-1-ol (Yan 7874), is commercially available, and we set out to analyze its properties. As test system we utilized human OX1 and OX2 orexin receptor-expressing Chinese hamster ovary (CHO) K1 cells as well as control CHO-K1 and neuro-2a neuroblastoma cells. Gq-coupling was assessed by measurement of intracellular Ca2+ and phospholipase C activity, and the coupling to Gi and Gs by adenylyl cyclase inhibition and stimulation, respectively. At concentrations above 1 μM, strong Ca2+ and low phospholipase C responses to Yan 7874 were observed in both OX1- and OX2-expressing cells. However, a major fraction of the response was not mediated by orexin receptors, as determined utilizing the non-selective orexin receptor antagonist N-biphenyl-2-yl-1-{[(1-methyl-1H-benzimidazol-2-yl)sulfanyl]acetyl}-L-prolinamide (TCS 1102) as well as control CHO-K1 cells. Yan 7874 did not produce any specific adenylyl cyclase response. Some experiments suggested an effect on cell viability by Yan 7874, and we thus analyzed this. Within a few hours of exposure, Yan 7874 markedly changed cell morphology (shrunken, rich in vacuoles), reduced growth, promoted cell detachment, and induced necrotic cell death. The effect was equal in cells expressing orexin receptors or not. Thus, Yan 7874 is a weak partial agonist of orexin receptors. It also displays strong off-target effects in the same concentration range, culminating in necrotic cell demise. This makes Yan 7874 unsuitable as orexin receptor agonist.

Synthesis and molecular docking study of some 5,6-dichloro-2-cyclopropyl-1H-benzimidazole derivatives bearing triazole, oxadiazole, and imine functionalities as potent inhibitors of urease

A new series of benzimidazole compounds including hydrazinecarbothioamide, 1,2,4-triazole, 1,3,4-oxadiazole and imine function were synthesized starting from 5,6-dichloro-2-cyclopropyl-1H-benzimidazole. All of the benzimidazole derivatives exhibited good urease inhibitor activity. Compound 6a proved to be the most potent showing an enzyme inhibitory activity with an IC₅₀=0.06µM. Molecular docking studies were also conducted on enzyme extracted from Jack bean urease to identify the binding mode of the newly synthesized compounds.

Synthesis and Biological Evaluation of Imines Structurally Related to Resveratrol as Dual Inhibitors of VEGF Protein Secretion and hTERT Gene Expression

A group of 28 N-benzylidene aniline derivatives structurally related to the natural stilbene resveratrol has been prepared through condensation of anilines with the corresponding aldehydes. The ability of these imines to inhibit proliferation of two tumor cell lines (HT-29 and MCF-7) and one non-tumor cell line (HEK- 293) was first determined. Subsequently, we determined the ability of some of the most cytotoxic compounds to inhibit the secretion of the VEGF-A factor in HT-29 cells and to downregulate the expression of the VEGF and hTERT genes, the latter one being involved in the activation of telomerase.

Improved tolerance to transplanting injury and chilling stress in rice seedlings treated with orysastrobin

In addition to their fungicidal activity, strobilurin-type fungicides are reported to show enhancing effects on crop growth and yield. Previous studies suggested that the fungicide has a mitigating effect on abiotic stresses. However, there are few reports about growth enhancement through abiotic stress alleviation by strobilurin-type fungicides, but the mechanism of action of the growth enhancement is still not clear. The present study revealed that orysastrobin enhanced rice seedling growth after root cutting injury and chilling stress. We also found that orysastrobin decreased the transpiration rate and increased ascorbate peroxidase and glutathione reductase activities. This stress alleviation was eliminated by the application of naproxen, a putative abscisic acid biosynthesis inhibitor. These results suggested that orysastrobin improved tolerance against transplanting injury and chilling stress in rice seedlings by inducing water-retaining activity through the suppression of transpiration, and also by inducing reactive oxygen scavenging activity thus inhibiting reactive oxygen species accumulation.

New 2-Imino-2H-Chromene-3(N-aryl)carboxamides as Potential Cytotoxic Agents

Synthesis and structure activity relationships of four series of novel 2-imino-2H-chromene-3(N-aryl) carboxamides (V-VIII) have been described by bioisosteric replacement of usually present ketone at 2nd position of coumarin with imine. Various substitutents are introduced on aryl and chromene ring of iminocoumarin to investigate the effect of lipophilicity and electronic properties of substituents on cytotoxic activity against four human cancer cell lines. Novel 2-imino-2H-chromene-3(N-aryl)carboxamides (V-VIII) were synthesized by the reaction of substituted 2- cyanoacetamides with different salicyaldehydes in the presence of sodium acetate in glacial acetic acid. Compound VIa showed potent activity against MCF-7 (IC50 = 8.5 μM), PC-3 (IC50 = 35.0 μM), A-549 (IC50 = 0.9 μM) and Caco-2 (IC50 = 9.9 μM) cell lines. The anticancer results revealed that most of the synthesized compounds showed equipotent activity with the standard 5-fluorouracil and docetaxel on Caco-2 and MCF-7 cell lines, respectively.

Double Null of Selenium-Glutathione Peroxidase-1 and Copper, Zinc-Superoxide Dismutase Enhances Resistance of Mouse Primary Hepatocytes to Acetaminophen Toxicity

This study was conducted to determine the impact of knockout of selenium (Se)–dependent glutathione peroxidase-1 (GPX1 /) or double knockout of GPX1 and copper, zinc (Cu, Zn)–superoxide dismutase (SOD1) on cell death induced by acetaminophen (APAP) and its major toxic metabolite N-acetyl-P-benzoquinoneimine (NAPQI). Primary hepatocytes were isolated from GPX1 /. double knockout of GPX1 and SOD1 (DKO), and their wild-type (WT) mice and were treated with 5 mM APAP or 100 μM NAPQI for 0, 6, and 12 hrs. Compared with the WT cells, the GPX1 / and DKO hepatocytes were more resistant (P < 0.05) to the APAP-induced cell death but less resistant to the NAPQI-induced cell death. The APAP-mediated glutathione (GSH) depletion was greater (P < 0.05) at 6 hrs in the WT cells than in the GPX1 / and DKO cells, whereas there was no genotype effect on the NAPQI-mediated GSH depletion. The DKO cells had lower (P < 0.05) microsomal cytochrome P450 2E1 activities, but higher (P < 0.05) glutathione reductase and thioredoxin reductase activities than the WT cells at 0 hrs, and they responded differently to the APAP and NAPQI treatments. Glutathione-S-transferase activity was not affected by genotypes or treatments. Neither APAP nor NAPQI induced nitric oxide production or protein nitration in cells of any genotype. However, the GPX1 and DKO cells were more resistant to peroxynitrite-mediated protein nitration than were the WT cells. In conclusion, double null of GPX1 and SOD1 enhanced the resistance of mouse primary hepatocytes to APAP toxicity by affecting events prior to or at NAPQI formation. While the double knockout attenuated the peroxynitrite-mediated protein nitration in hepatocytes, no protein nitration was detected in these cells treated with APAP or NAPQI.

Selective Inducible Nitric Oxide Synthase Inhibitor Reversed Zinc Chloride-Induced Spatial Memory Impairment via Increasing Cholinergic Marker Expression

Zinc, an essential micronutrient and biochemical element of the human body, plays structural, catalytic, and regulatory roles in numerous physiological functions. In the current study, the effects of a pretraining oral administration of zinc chloride (10, 25, and 50 mg/kg) for 14 consecutive days and post-training bilateral intra-hippocampal infusion of 1400W as a selective inducible nitric oxide synthase (iNOS) inhibitor (10, 50, and 100 μM/side), alone and in combination, on the spatial memory retention in Morris water maze (MWM) were investigated. Animals were trained for 4 days and tested 48 h after completion of training. Also, the molecular effects of these compounds on the expression of choline acetyltransferase (ChAT), as a cholinergic marker in the CA1 region of the hippocampus and medial septal area (MSA), were evaluated. Behavioral and molecular findings of this study showed that a 2-week oral administration of zinc chloride (50 mg/kg) impaired spatial memory retention in MWM and decreased ChAT expression. Immunohistochemical analysis of post-training bilateral intra-hippocampal infusion of 1400W revealed a significant increase in ChAT immunoreactivity. Furthermore, post-training bilateral intra-hippocampal infusion of 1400W into the CA1 region of the hippocampus reversed zinc chloride-induced spatial memory impairment in MWM and significantly increased ChAT expression in comparison with zinc chloride-treated animals. Taken together, these results emphasize the role of selective iNOS inhibitors in reversing zinc chloride-induced spatial memory deficits via modulation of cholinergic marker expression.

EVALUATION OF ANTIOXIDANT ACTIVITY OF SOME IMINES DERIVATIVES OF L-ARGININE

L-Arginine is an a-amino acid which plays important roles in different diseases or processes, such as Alzheimer disease, inflammatory process, healing and tissue regeneration and it also could be useful as an anti-atherosclerotic agent.

AIM

Considering the large amount of studies on the beneficial effects of different antioxidants, this paper is focused on the evaluation of the antioxidant potential of some imine derivatives, synthesized by the authors and described in a previous article.

MATERIAL AND METHODS

The evaluation of the antioxidant power was performed using phosphomolydenum-reducing antioxidant power (PRAP) and ferric reducing antioxidant power (FRAP) assays, tests described in the literature and which are used with some minor modifications.

RESULTS

It was found that most of the imine derivatives are more active than the L-Arginine in the PPAP and FRAP assays. The most active derivative was the compound obtained by condensation of L-arginine with 2,3-dihydroxybenzaldehyde (2k) and 2-nitrobenzaldehyde (2g).

CONCLUSIONS

Following the described protocol, some imine derivatives of L-arginine were evaluated in terms of antioxidant potential using in vitro methods. The most favorable influence was obtained by the aromatic substitution with nitro and hydroxyl, the corresponding derivatives being the most active derivatives compared to L-arginine.

Synthesis, Spectral investigation (¹H, ¹³C) and Anti-microbial Screening of benzophenone imines

New series of benzophenone imines with general formula Ph2-C=NR; R = Benzyl, 4-Fluorobenzyl, Naphthyl, Phenyl, 4-Nitrophenyl were synthesized by condensation of dichlorodiphenylmethane and different aromatic primary amines (1:1) Those imines were characterized by different physiochemical and spectroscopic techniques like melting point, elemental analysis, FT-IR, multinuclear NMR (¹H, ¹³C). After characterization, imines were subjected to anti-microbial activities. All compounds showed promising activity against different bacterial strains like Escherichia coli, Bacillussubtilis, Pasturellam ultocida and Staphylococcus aureus as well as fungal strains like Alternata alternaria, Ganoderma lucidium, Penicillium notatum and Trichoderma harzianum using Amoxicillin and Flucanazole as a standard drugs respectively.

Biophysical insights into the intercalative interaction of surfactant cobalt(III) complexes of certain diimine ligands bound to yeast tRNA: Effects of hydrophobicity

The interaction of two surfactant cobalt(III) complexes, cis-[Co(ip)₂(DA)₂](ClO₄)₃ 1 and cis-[Co(dpq)₂(DA)₂](ClO₄)₃ 2 where ip=imidazo[4,5-f][1,10]phenanthroline and dpq=dipyrido[3,2-d:2'-3'-f]quinoxaline with yeast tRNA have been explored by using electronic absorption, competitive binding, electrochemical studies and viscosity measurements. The results suggest that these complexes can bind to tRNA by intercalation. The presence of hydrophobic diimine ligand and the long aliphatic double chains of these complexes facilitate its intercalative interaction with the hydrophobic interior of the tRNA. The extent of tRNA binding of complex 2 has greater affinity than that of complex containing imidazo[4,5-f][1,10]phenanthroline ligands.

Anticancer, photoluminescence and electrochemical properties of structurally characterized two imine derivatives

Two imine compounds, 4-[(E)-(2-methoxybenzylidene)amino]phenol (L(1)) and 4-[(E)-(3,4-dimethoxybenzylidene)amino]phenol (L(2)) were synthesized and characterized by the analytical and spectroscopic methods. The electrochemical and photoluminescence properties of the imine compounds L(1) and L(2) were investigated in different solvents. The compounds L(1) and L(2) show different redox processes at some potentials. The molecular structures of two Schiff base compounds are broadly similar, differing principally in the position, the number of methoxy (-OCH3) groups and dihedral angles between aromatic rings. While the compound L(1) has only one methoxy group located on the o-position with respect to the imine bond (C=N), the L(2) contains two methoxy groups on the p-m-positions with respect to the imine bond. The imine compounds show two or three emission bands in the 619-832 nm range in organic solvents. In the 1.0×10(-3) M concentration, the compounds have the highest excitation and emission bands. The imine compounds L(1) and L(2) were screened for their in vitro cytotoxicity on HeLa cell lines using the xCELLigence system (Real Time Cell Analyzer).

EFFICACY OF FUNGICIDES AGAINST CALONECTRIA PAUCIRAMOSA IN POT AZALEA

Calonectria (formerly Cylindrocladium) infection of pot azalea (Rhododendron simsii Planch) is an important disease problem in which usually one or two of the four plants per pot show progressing leaf and especially stem lesions, leading to mortality of the respective plant and rendering the pot unmarketable. This may occur in a later stage of the growing season, leading to significant commercial losses. The main objective of this study was to test a range of fungicides for their efficacy against this pathogen. To test the fungicides, a bioassay was first developed in which mycelium and conidiospores of the pathogen were produced on Potato Dextrose Agar, blended in water, and dilutions of the resulting suspension inoculated at the base of 11-week-old cuttings three weeks after they had been trimmed. Disease progression was monitored up to 7 weeks post inoculation and a disease index on a scale of 0 to 3 was established. In the actual efficacy trial, the following fungicides (with corresponding active ingredient(s)) were tested as preventive treatments: Topsin M 70 WG (thiophanate-methyl), Sporgon (prochloraz), Signum (boscalid+pyraclostrobin), Switch (cyprodinyl+fludioxonil), Flint 50WG (trifloxystrobin), Ortiva Top (azoxystrobin+difenoconazole) and Fungaflor (imazalil). Disease expression started after about 2 weeks, increased approximately 1 index level, and leveled off 5 weeks after inoculation. The best control was observed with Sporgon, Ortiva Top and Signum. Switch produced intermediate effects and insufficient control was observed with Topsin, Flint and Fungaflor. These results explain why specific standard fungicide treatments, such as those with Topsin, fail to control the disease, while they can be effective against a different Calonectria species such as C. pseudonaviculata, the cause of boxwood blight.

Different toxicity of the strobilurin fungicides kresoxim-methyl and trifloxistrobin to Venturia inaequalis isolates from Serbia

Sensitivity of monosporial isolates of V. inaequalis, originated from apple orchards previously exposed (commercial and experimental) and those originated from location where fungicides had never been used (wild type), to strobilurin fungicides kresoxim-methyl and trifloxistrobin was investigated in this study. The experiments were carried out in laboratory using in vitro and in vivo methods. Mycelia growth inhibition on PDA medium with kresoxim-methyl and trifloxistrobin was monitored and sensitivity parameters (EC50 values) were determined using probit analysis. The isolates sensitivity in vivo was tested on apple seedlings using inoculation method. The EC50 values were ranging from 0.066-2.033 and 0.011-0.323 µg mL(-1) for kresoxim-methyl and trifloxistrobin, respectively. The wild type of isolates showed a normal susceptibility to kresoxim-methyl and trifloxistrobin, while isolates originated from experimental and commercial orchard where those fungicides had been used extensively, showed significantly lower sensitivity to the both strobilurin fungicides. The isolate that showed the resistance to kresoxim-methyl and trifloxistrobin in vitro test, also showed reduced sensitivity in vivo test and could not been controlled satisfactory by fungicide concentrations that are commercially used, as well as by double higher, after apple seedlings inoculation.