10T024A, a new phenazine derivative, as a radical scavenger and a prostaglandin, leukotriene release suppressor

We identified a new radical scavenger, 10T024A (C(15)H(12)N(2)O(4)), from a culture of the Streptomyces sp. Spectroscopic elucidation indicated that this compound is a new phenazine derivative. 10T024A showed radical-scavenging activity with an ED(50) of 125 μM. Moreover, it showed prostaglandin D(2) (PGD(2)) and leukotriene B(4) (LTB(4)) release suppressive activity in rat basophilic leukemia (RBL-2H3) cells, at IC(50): 8 μM and 10 μM respectively.     

Arachidonic acid metabolism by canine tracheal epithelial cells. Product formation and relationship to chloride secretion

Canine tracheal epithelial cells freshly isolated from mongrel dog trachea were used to study relationships between arachidonic acid metabolism and chloride ion movement. High performance liquid chromatography (HPLC) analysis of the cell incubation media after the addition of A23187 showed the presence of prostaglandin H synthase and lipoxygenase-derived metabolites. The major prostaglandin H synthase metabolite identified by HPLC, gas chromatography, and mass spectrometry was prostaglandin (PG) D2. The major lipoxygenase metabolites were leukotriene (LT) C4 and LTB4. LTB4 was identified by HPLC, UV spectroscopy, and gas chromatography. Straight phase HPLC of the methyl esters indicated only a minor formation of LTB4 isomers. LTC4 was identified by HPLC, UV spectroscopy, and conversion to LTD4 by gamma-glutamyl transpeptidase. Analysis by radioimmunoassays indicated approximately 1-2 ng of LTB4 and peptide LT formed by 10(6) cells after A23187 stimulation. The addition of ionophore A23187 caused a rapid release of arachidonic acid metabolites which was completed within 5 min of stimulation. Cl- secretion was measured in parallel studies of excised tracheas in Ussing chambers. Cl- secretion occurred at 2-3 min after the addition of ionophore, and the most rapid change occurred with the highest PGD2 concentrations. Indomethacin produced a concentration-dependent inhibition of PGD2 formation and Cl- movement. The addition of PGE2, PGD2, and PGH2 effectively stimulated Cl- secretion. LTC4 also stimulated Cl- secretion, but the stimulation was inhibited by indomethacin. These results indicate that canine tracheal epithelial cells metabolize arachidonic acid via both prostaglandin H synthase and lipoxygenase enzymes. It appears that endogenous PGD2 formation is the important variable controlling the Cl- ion movement in canine trachea.     

Biotransformations of 6',7'-dihydroxybergamottin and 6',7'-epoxybergamottin by the citrus-pathogenic fungi diminish cytochrome P450 3A4 inhibitory activity

Penicillium digitatum, as well as five other citrus pathogenic species, (Penicillium ulaiense Link, Geotrichum citri Link, Botrytis cinerea P. Micheli ex Pers., Lasiodiplodia theobromae (Pat.) Griffon & Maubl., and Phomopsis citri (teleomorph Diaporthe citri)) were observed to convert 6',7'-epoxybergamottin (1) into 6',7'-dihydroxybergamottin (2), bergaptol (3), and an opened lactone ring metabolite 6,7-furano-5-(6',7'-dihydroxy geranyloxy)-2-hydroxy-hydrocoumaric acid (4). Metabolism of 2 by these fungi also proceeded to 4. The structure of 4 was established by high resolution mass spectrometry and (1)H and (13)C NMR techniques. The inhibitory activity of 4 towards human intestinal cytochrome P450 3A4 (CYP3A4) was greatly decreased (IC(50) >172.0 μM) compared to 2 (IC(50)=0.81 μM).     

Synthesis, SAR, and preliminary mechanistic evaluation of novel antiproliferative N⁶,5'-bis-ureido- and 5'-carbamoyl-N⁶-ureidoadenosine derivatives

We have developed efficient methods for the preparation of N(6),5'-bis-ureidoadenosine derivatives and their 5'-carbamoyl-N(6)-ureido congeners. Treatment of 5'-azido-5'-deoxy-N(6)-(N-alkyl or -arylurea)adenosine derivatives (6a-d) with H(2)/Pd-C or Ph(3)P/H(2)O, followed by N-methyl-p-nitrophenylcarbamate gave N(6),5'-bis-ureido products 7a-d in 49-78% yield. Analogous derivatives in the 5'-carbamoyl-N(6)-ureido series were prepared by treatment of 2',3'-bis-O-TBS-adenosine (11) with N-methyl-p-nitrophenylcarbamate followed by acylation with appropriate isocyanates which gave 13a-d in 45-69% yield. A more versatile route for obtaining potentially vast libraries of compounds from both series was achieved by treatment of 5'-N-methylureido- or 5'-N-methylcarbamoyladenosine derivatives with ethylchlorformate to give N(6)-ethoxycarbonyl derivatives (9 and 14) in 55-63% yields, respectively. Simple heating of 9 or 14 in the presence of primary alkyl- or arylamines gave the corresponding N(6),5'-bis-ureido- or 5'-carbamoyl-N(6)-ureidoadenosine derivatives in good yields (33-72% and 39-83%; 10a-e and 15a-e, respectively). Significant antiproliferative activities (IC(50)≈4-10 μg/mL) were observed for a majority of the N(6),5'-bis-ureido derivatives, whereas the 5'-carbamoyl-N(6)-ureido derivatives were generally less active (IC(50) >100 μg/mL). A 2',3'-O-desilylated derivative (5'-amino-5'-deoxy-5'-N-methylureido-N(6)-(N-phenylcarbamoyl)adenosine, 16) was shown to inhibit binding of 16 of 441 protein kinases to immobilized ATP-binding site ligands by 30-40% in a competitive binding assay at 10 μM. Compound 16 was also shown to bind to bone morphogenetic protein receptor 1b (BMPR1b) with a Kd=11.5 ± 0.7 μM.     

Evaluation of inhibitors of eicosanoid synthesis in leukocytes: possible pitfall of using the calcium ionophore A23187 to stimulate 5' lipoxygenase

The effect on arachidonate metabolism of two compounds (BW755C and benoxaprofen) which have been reported to inhibit 5' lipoxygenase in leukocytes has been evaluated in human polymorphonuclear leukocytes (PMN) stimulated with the calcium ionophore A23187 and serum-treated zymosan (STZ). The syntheses of leukotriene B4 (LTB4) and thromboxane B2 (TXB2) from endogenous substrate were determined by specific radioimmunoassays as indicators of 5' lipoxygenase and cyclo-oxygenase activity in the PMN respectively. Benoxaprofen inhibited the synthesis of leukotriene B4 by human PMN stimulated with the calcium ionophore A23187, but it was approximately 5 times less potent than BW755C. However, benoxaprofen (IC50 1.6 X 10(-4)M) was approximately 100 times less potent than BW755C (IC50 1.7 X 10(-6)M) at inhibiting leukotriene B4 synthesis induced by serum-treated zymosan. Both drugs inhibited thromboxane synthesis by leukocytes stimulated with A23187 or serum-treated zymosan at similar concentrations (approximately 5 X 10(-6)M). The data obtained using STZ as stimulus are consistent with previous in vivo studies and indicate that benoxaprofen is a relatively selective inhibitor of cyclo-oxygenase. However, this selectivity was far less apparent when A23187 was used as a stimulus to release the eicosanoids which suggests that this inhibition could be via an indirect mechanism and therefore A23187 should be used with caution as a stimulus of 5' lipoxygenase for evaluating inhibitors of eicosanoid synthesis.     

Natural forms of vitamin E and 13'-carboxychromanol, a long-chain vitamin E metabolite, inhibit leukotriene generation from stimulated neutrophils by blocking calcium influx and suppressing 5-lipoxygenase activity, respectively

Leukotrienes generated by 5-lipoxygenase (5-LOX)-catalyzed reaction are key regulators of inflammation. In ionophore-stimulated (A23187; 1-2.5 μM) human blood neutrophils or differentiated HL-60 cells, vitamin E forms differentially inhibited leukotriene B(4) (LTB(4)) with an IC(50) of 5-20 μM for γ-tocopherol, δ-tocopherol (δT), and γ-tocotrienol, but a much higher IC(50) for α-tocopherol. 13'-Carboxychromanol, a long-chain metabolite of δT, suppressed neutrophil- and HL-60 cell-generated LTB(4) with an IC(50) of 4-7 μM and potently inhibited human recombinant 5-LOX activity with an IC(50) of 0.5-1 μM. In contrast, vitamin E forms had no effect on human 5-LOX activity but impaired ionophore-induced intracellular calcium increase and calcium influx as well as the subsequent signaling including ERK1/2 phosphorylation and 5-LOX translocation from cytosol to the nucleus, a key event for 5-LOX activation. Further investigation showed that δT suppressed cytosolic Ca(2+) increase and/or LTB(4) formation triggered by ionophores, sphingosine 1-phosphate, and lysophosphatidic acid but not by fMLP or thapsigargin, whereas 13'-carboxychromanol decreased cellular production of LTB(4) regardless of different stimuli, consistent with its strong inhibition of the 5-LOX activity. These observations suggest that δT does not likely affect fMLP receptor-mediated signaling or store depletion-induced calcium entry. Instead, we found that δT prevented ionophore-caused cytoplasmic membrane disruption, which may account for its blocking of calcium influx. These activities by vitamin E forms and long-chain carboxychromanol provide potential molecular bases for the differential anti-inflammatory effects of vitamin E forms in vivo.     

Characterization and biologic properties of 5,12-dihydroxy derivatives of eicosapentaenoic acid, including leukotriene B5 and the double lipoxygenase product

Leukotriene B5 (LTB5) and three stereoisomers were prepared biosynthetically from eicosapentaenoic acid and compared with the analogous derivatives of arachidonic acid for their chemotactic and aggregating effects on human neutrophilic polymorphonuclear leukocytes. Leukotriene B4 (LTB4), LTB5, and the 6-trans-diastereoisomers of each were generated by activating polymorphonuclear leukocytes with the calcium ionophore A23187 in the presence of 14C-labeled and unlabeled arachidonic acid or 14C-labeled and unlabeled eicosapentaenoic acid, respectively. The double lipoxygenase products, (5S,12S)-6-trans-8-cis-LTB4 and (5S,12S)-6-trans-8-cis-LTB5, were generated from 5S-hydroxyeicosatetraenoic acid and racemic 5-hydroxyeicosapentaenoic acid intermediates by incubation with platelet sonicates. The products of each reaction were isolated by reverse-phase-high performance liquid chromatography and identified by their retention times relative to the appropriate totally synthetic standards, ultraviolet absorption spectra, immunoreactivity in a radioimmunoassay for LTB4, and, for all but the double lipoxygenase products, by incorporation of radiolabel from the specific polyunsaturated fatty acid source. When the concentration of LTB5 eliciting maximum chemotactic response of human polymorphonuclear leukocytes, 50 ng/ml (1.5 X 10(-7) M), and that eliciting a maximum aggregation response, 20 ng/ml (5.9 X 10(-8) M), were compared with the interpolated values of LTB4 eliciting comparable effects, the potency of LTB5 relative to LTB4 was approximately 1:8 as a chemotactic agent and about 1:20 as an aggregating agent. The double lipoxygenase products and the resolved 6-trans-diastereoisomers of the pentaene and tetraene series were about 2 logs less active as chemotactic factors than LTB4 and only (5S,12S)-6-trans-8-cis-LTB4 had even minimal aggregating activity.     

Mast cell mediators prostaglandin-D2 and histamine activate human eosinophils.

Airway damage secondary to eosinophil activation is thought to contribute to the development of asthma. Using the fluorescent dye FURA-2 to measure the concentration of cytosolic calcium, we found that supernatants from anti-IgE-stimulated human lung mast cells increased cytosolic calcium in human eosinophils. We then examined the major mast cell mediators (histamine, PGD2, platelet-activating factor (PAF), eosinophil chemotactic factor of anaphylaxis (ECF-A), leukotriene (LT)C4 and LTB4) for their ability to increase cytosolic calcium in eosinophils. We found that both PAF (5 x 10(-9) to 5 x 10(-6) M) and PGD2 (two of five donors responsive at 1 x 10(-9) M) were potent stimuli for calcium mobilization. LTB4 (10(-8), 10(-7) M) and histamine were also active, although higher concentrations of histamine were required to see a response (3 x 10(-7) to 10(-5) M). LTC4, val-ECF-A, and ala-ECF-A were inactive. The effects of PGD2 and histamine were specific for eosinophils, although LTB4 and PAF increased calcium in both neutrophils and eosinophils. The histamine-induced increase in intracellular calcium was not blocked by the H1 or H2 antagonists pyrilamine or cimetidine (10(-4) M), respectively; however, the response to 10(-6) M histamine was completely blocked by the specific H3 antagonist thioperamide (10(-6) M). To evaluate the relative contribution of these stimulatory mast cell mediators on the calcium mobilizing activity in supernatants from anti-IgE-stimulated human lung mast cell (HLMC), we examined the effect of supernatants from HLMC pretreated with indomethacin and/or the 5-lipoxygenase pathway inhibitor MK886. These supernatants were added to FURA-2-loaded eosinophils that had been preincubated with thioperamide and/or the PAF antagonist WEB-2086. We found that the increase in eosinophil calcium in response to supernatants from anti-IgE-stimulated-HLMC was totally inhibited only when the mast cells were challenged in the presence of indomethacin and MK886, and the eosinophils were preincubated with thioperamide. WEB-2086 had little effect. When we examined the effect of these mediators on eosinophil secretory function, we found that PGD2 (not histamine) primed eosinophils for enhanced release of LTC4 in response to the calcium ionophore A23187. We conclude that the activation of eosinophils by PGD2 and other mast cell products may contribute to airways inflammation that is characteristic of asthma.     

Novel lipoxygenase inhibitors, tetrapetalone B, C, and D from Streptomyces sp

Three novel lipoxygenase inhibitors, tetrapetalone B (2, C(28)H(35)NO(9)), C (3, C(26)H(34)NO(8)), and D (4, C(28)H(36)NO(10)), were isolated from a culture broth of Streptomyces sp. USF-4727 that produced a lipoxygenase inhibitor tetrapetalone A (1) simultaneously. Each chemical structure was revealed by spectroscopic evidence, this suggests that these three compounds are structurally related to 1. They had a tetracyclic skeleton and a beta-D-rhodinosyl moiety. Tetrapetalone B, C, and D inhibited soybean lipoxygenase with IC(50): 320, 360, and 340 microM respectively.     

Hydrocortisone inhibits rat basophilic leukemia cell mediator release induced by neutrophil-derived histamine releasing activity as well as by anti-IgE.

We determined the ability of hydrocortisone to inhibit rat basophilic leukemia cell mediator release induced by anti-IgE and by neutrophil-derived histamine-releasing activity (HRA-N). Serotonin release induced by HRA-N and anti-IgE was inhibited by 78 +/- 5 and 70 +/- 4%, respectively (IC50 7.5 x 10(-7)M) by hydrocortisone (10(-5)M). HRA-N does not cause arachidonic acid metabolism, however, anti-IgE induced the generation of PGD2 and leukotriene (LT)C4, and the generation of both mediators was inhibited by 10(-5)M hydrocortisone (IC50 = 4.8 x 10(-7)M, and 3.6 x 10(-9)M, respectively). Inhibition required at least 5 to 6 h of hydrocortisone exposure and was maximal after 22 h. The observed effects of hydrocortisone could be reproduced by human recombinant lipocortin-I (5 x 10(-7)M). Hydrocortisone, 10(-5)M, was a less potent inhibitor of calcium ionophore A23187-mediated serotonin release and PGD2 and LTC4 generation (inhibition of 20 +/- 2, 17 +/- 10, and 37 +/- 10%, respectively). Inasmuch as A23187-induced stimulation is not dependent on receptor coupling, the enhanced ability of hydrocortisone to inhibit IgE- and HRA-N-mediated events as compared with A23187 suggests that one possible site of action of hydrocortisone may be interruption of receptor-effector signals. In the presence of arachidonic acid, hydrocortisone-treated cells released as much LTB4 and PGD2 as control cells, however, serotonin release and LTC4 generation were inhibited 50 and 55%, respectively. Thus, these data suggest that hydrocortisone has three possible sites of action: 1) inhibition of phospholipase A2 activity, 2) inhibition of glutathione-s-transferase, and 3) inhibition of serotonin release by a third mechanism, possibly by interrupting the coupling of receptor and effector systems.     

Characterization of leukotriene B4 synthesis in canine polymorphonuclear leukocytes.

The synthesis and release of leukotriene B4 (LTB4) from canine polymorphonuclear leukocytes (PMNs) was characterized in terms of incubation time, temperature and effects of calcium ionophore A23187 concentrations. Maximal LTB4 concentrations were determined when canine PMNs were incubated with 10 microM A23187. Increasing LTB4 concentrations were determined through 10 min incubation. The maximal LTB4 concentrations (310 +/- 30 pg LTB4/2.5 x 10(5) cells) determined at 10 min did not change through a 55 min incubation period. Greater LTB4 concentrations were synthesized by canine PMNs at 37 degrees C (268 +/- 12 pg LTB4/2.5 x 10(5) cells) than at 25 degrees C (206 +/- 11 pg LTB4/2.5 x 10(5) cells) or 5 degrees C (59 +/- 3 pg LTB4/2.5 x 10(5) cells). The synthesis of LTB4 in canine PMNs was inhibited by incubation of the cells with either of two known lipoxygenase inhibitors, BWA4C or BW755C. BWA4C inhibited LTB4 synthesis with an approximate IC50 = 0.1 microM, whereas BW755C inhibited LTB4 synthesis with an approximate IC50 = 10 microM. These results indicate canine PMNs have the capability to synthesize large quantities of LTB4 when stimulated with calcium ionophore A23187. Furthermore, the 5-lipoxygenase inhibitors BWA4C, an acetohydroxyamic acid, and BW755C, a phenyl pyrazoline, can readily inhibit LTB4 synthesis in canine PMNs.     

多根乌头中二萜生物碱成分

为研究多根乌头(AconitumkarakolicumRapaics)中二萜生物碱成分,本研究采用正反相硅胶柱和高效液相等色谱分离方法,从中分离得到15个二萜生物碱;通过多种波谱手段以及文献对比的方法鉴定其结构分别为aconitine(1),3-deoxyaconitine(2),16-epipyroaconine(3),neoline(4),indaconitine(5),14-benzoyl-8-O-methylaconitine(6),spicatineA(7),15-α-hydroxyneoline(8),taurenine(9),14-benzoylaconine(10),14-benzoylaconine-8-oleate(11),lappaconitine(12),beiwudine(13),13-hydroxyfranchetine(14)和8-O-linoleoyl-14-benzoylaconine(15),化合物3~15为首次从该植物中分离得到。采用MTT法和叶碟法分别考察了部分化合物的抗肿瘤和拒食活性,化合物14-benzoylaconine-8-oleate(11)对人乳腺癌MCF-7细胞、人肺癌H460细胞、肝癌HepG2细胞的IC50值分别为11.9、27.6和31.8μM。乌头碱型的二萜生物碱aconitine(1)、3-deoxyaconitine(2)、indaconitine(5)和beiwudine(13)表现出一定的拒食活性的活性(EC50<2mg/cm^2)。     

Enhanced 5-lipoxygenase activity in lung macrophages compared to monocytes from normal subjects

We compared lipoxygenase activities of lung macrophages obtained from bronchoalveolar lavage to activities of blood monocytes purified by using discontinuous plasma/Percoll density gradients and adherence to tissue culture plastic in five normal subjects. Cells were incubated with ionophore A23187 (10(-9) to 10(-5) M) or arachidonic acid (0.12 to 80 microM) for 1 to 60 min at 37 degrees C to construct dose-response and time-dependence curves of lipoxygenase product generation. Products were identified and were quantified by using high-pressure liquid chromatography and ultraviolet spectroscopy. Under all conditions of product generation, both macrophages and monocytes generated predominantly (5S,12R)-dihydroxy-(6Z, 8E, 10E, 14Z)-eicosatetraenoic acid (leukotriene B4 (LTB4] and (5S)-hydroxy-(6E, 8Z, 11Z, 14Z) - eicosatetraenoic acid (5 - HETE), but, in each subject, macrophages invariably released greater amounts of LTB4 and 5-HETE than monocytes. In response to A23187, macrophages released a maximum of 183 +/- 96 pmol of LTB4 and 168 +/- 108 pmol of 5-HETE per 10(6) cells (mean +/- SEM), whereas monocytes released only 16 +/- 1 and 18 +/- 8 pmol per 10(6) cells of LTB4 and 5-HETE, respectively. After adding arachidonic acid, macrophages released a maximum of 52 +/- 21 pmol of LTB4 and 223 +/- 66 pmol of 5-HETE, whereas monocytes released no detectable products. The results suggest that mononuclear phagocyte maturation in the lung may be accompanied by an enhanced ability to generate 5-lipoxygenase products.     

Synthesis, structural elucidation, DNA-PK inhibition, homology modelling and anti-platelet activity of morpholino-substituted-1,3-naphth-oxazines

A number of new angular 2-morpholino-(substituted)-naphth-1,3-oxazines (compound 10b), linear 2-morpholino-(substituted)-naphth-1,3-oxazines (compounds 13b-c), linear 6, 7 and 9-O-substituted-2-morpholino-(substituted)-naphth-1,3-oxazines (compounds 17-22, 24, and 25) and angular compounds 14-16 and 23 were synthesised. The O-substituent was pyridin-2yl-methyl (15, 18, and 21) pyridin-3yl-methyl (16, 19, and 22) and 4-methylpipreazin-1-yl-ethoxy (23-25). Twelve compounds were tested for their inhibitory effect on collagen induced platelet aggregation and it was found that the most active compounds were compounds 19 and 22 with IC(50)=55±4 and 85±4 μM, respectively. Furthermore, the compounds were also assayed for their ability to inhibit DNA-dependent protein kinase (DNA-PK) activity. The most active compounds were 18 IC(50)=0.091 μM, 24 IC(50)=0.191 μM, and 22 IC(50)=0.331 μM. Homology modelling was used to build a 3D model of DNA-PK based on the X-ray structure of phosphatidylinositol 3-kinases (PI3Ks). Docking of synthesised compounds within the binding pocket and structure-activity relationships (SAR) analyses of the poses were performed and results agreed well with observed activity.     

Enhanced superoxide anion generation but reduced leukotriene B4 productivity in thioglycollate-elicited peritoneal macrophages

Lipoxygenase metabolism of arachidonic acid was compared between peritoneal macrophages from untreated rats and those from rats on day 7 after intraperitoneal injection of thioglycollate broth (TG). Resident macrophages (M phi) from untreated rats produced mainly LTB4 (303 +/- 25 pmol/5 x 10(6) cells) and 5-HETE (431 +/- 56 pmol/5 x 10(6) cells) when stimulated with 5 micrograms/ml calcium ionophore A23187 for 20 min at 37 degrees C. On the other hand, TG-elicited M phi generated less amounts of lipoxygenase metabolites (157 +/- 10 pmol LTB4 and 319 +/- 19 pmol 5-HETE/5 x 10(6) cells) with the same stimulus. Then, leukotriene productivity was examined by using subcellular fractions of each M phi lysate and an unstable epoxide intermediate, leukotriene A4. LTA4 hydrolase activity was mainly contained in soluble fractions from the both groups of M phi. The cytosol fraction from the resident M phi exhibited the following specific and total activity; 2.2 +/- 0.1 nmol LTB4/mg protein/5 min and 12.2 +/- 0.5 nmol LTB4/5 min per 10(8) cells. On the contrary, the cytosol fraction from the TG-elicited M phi showed 1.9 +/- 0.1 nmol LTB4/mg protein/5 min and 9.6 +/- 0.3 nmol LTB4/5 min per 10(8) cells. The resident M phi, however, generated 0.14 +/- 0.04 nmol O2-/min/4 x 10(5) cells whereas the TG-elicited M phi did 0.49 +/- 0.13 nmol O2-/min/4 x 10(5) cells when stimulated with wheat germ lectin. These results suggest that the TG-elicited macrophages show enhanced superoxide production but generate less lipoxygenase metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metronidazole acid acyl sulfonamide: a novel class of anticancer agents and potential EGFR tyrosine kinase inhibitors

A series of novel metronidazole derivatives were recently reported as potent anticancer agents targeting EGFR and HER-2 by our group [Qian, Y.; Zhang, H. J.; Zhang, H.; Xu, C.; Zhao, J.; Zhu, H. L. Bioorg. Med. Chem.2010, 18, 4991]. Based on the previous results, we designed and synthesized a new series of metronidazole acid acyl sulfonamide derivatives and a new series of phenylacetyl benzenesulfonamide derivatives and their anticancer activities were evaluated as potential EGFR and HER-2 kinase inhibitors. Among all the compounds, compound 12 displayed the most potent inhibitory activity EGFR and HER-2 (IC(50)=0.39 μM for EGFR and IC(50)=1.53 μM for HER-2) and it also showed the most potent growth inhibitory activity against A549 and B16-F10 cancer cell line in vitro, with an IC(50) value of 1.26 μg/mL for A549 and 0.35 μg/mL for B16-F10. Docking simulation was further performed to position compound 12 into the EGFR active site to determine the probable binding model.     

6-Nitrobenzimidazole derivatives: potential phosphodiesterase inhibitors: synthesis and structure-activity relationship

6-Nitrobenzimidazole derivatives (1-30) synthesized and their phosphodiesterase inhibitory activities determined. Out of thirty tested compounds, ten showed a varying degrees of phosphodiesterase inhibition with IC(50) values between 1.5±0.043 and 294.0±16.7 μM. Compounds 30 (IC(50)=1.5±0.043 μM), 1 (IC(50)=2.4±0.049 μM), 11 (IC(50)=5.7±0.113 μM), 13 (IC(50)=6.4±0.148 μM), 14 (IC(50)=10.5±0.51 μM), 9 (IC(50)=11.49±0.08 μM), 3 (IC(50)=63.1±1.48 μM), 10 (IC(50)=120.0±4.47 μM), and 6 (IC(50)=153.2±5.6 μM) showed excellent phosphodiesterase inhibitory activity, much superior to the standard EDTA (IC(50)=274±0.007 μM), and thus are potential molecules for the development of a new class of phosphodiesterase inhibitors. A structure-activity relationship is evaluated. All compounds are characterized by spectroscopic parameters.     

Anti-inflammatory phloroglucinol derivatives from Hypericum empetrifolium

Phytochemical investigation of Hypericum empetrifolium Willd. (Clusiaceae), a species native to Greece and Turkey has led to the bioassay-guided identification of two acylphloroglucinol derivatives with potent in vitro anti-inflammatory activity. Using NMR spectroscopy and mass spectrometry, the acylphloroglucinol derivatives were characterized as 3-geranyl-1-(2'-methylpropanoyl)phloroglucinol (1) and 3-geranyl-1-(2'-methylbutanoyl)phloroglucinol (2). Hypotheses are proposed regarding the biosynthetic origin of these and similar acylphloroglucinols from related Hypericum species. Compounds 1 and 2 were evaluated for in vitro inhibitory activity against COX-1, COX-2 and 5-LOX catalyzed LTB(4) formation. Compound 1 displayed good activity (IC(50) values: 6.0, 29.9, and 2.2 μM, respectively) in all three assays. Compound 2 showed good activity (IC(50) value: 5.8 μM) against LTB(4) formation and moderate activity (IC(50) value: 26.2 μM) against COX-1.     

Synthesis, characterization, antiamoebic activity and cytotoxicity of new pyrazolo[3, 4-d]pyrimidine-6-one derivatives

A new series of pyrazolo[3,4-d]pyrimidine-6-one derivatives (2a-2j) were prepared by using the Biginelli multicomponent cyclocondensation of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (1a), different aromatic aldehydes, and urea with a catalytic amount of HCl at reflux temperature. These compounds were characterized by IR, (1)H NMR, (13)C NMR, and Mass spectral data. In vitro antiamoebic activity was performed against HM1:IMSS strain of Entamoeba histolytica. The results showed that the compounds 2b, 2i, and 2j with IC(50) values of 0.37 μM, 0.04 μM, and 0.06 μM, respectively, exhibited better antiamoebic activity than the standard drug metronidazole (IC(50)?=?1.33 μM). The toxicological studies of these compounds on human breast cancer MCF-7 cell line showed that the compounds 2b, 2i, and 2j exhibited >80% viability at the concentration range of 1.56-50 μM.     

Bimetallic PtM (M=Pd, Ir) nanoparticle decorated multi-walled carbon nanotube enzyme-free, mediator-less amperometric sensor for H₂O₂

A new highly catalytic and intensely sensitive amperometric sensor based on PtM (where M=Pd, Ir) bimetallic nanoparticles (NPs) for the rapid and accurate estimation of hydrogen peroxide (H(2)O(2)) by electrooxidation in physiological conditions is reported. PtPd and PtIr NPs-decorated multiwalled carbon nanotube nanocatalysts (PtM/MWCNTs) were prepared by a modified Watanabe method, and were characterized by XRD, TEM, ICP, and XAS. The sensors were constructed by immobilizing PtM/MWCNTs nanocatalysts in a Nafion film on a glassy carbon electrode. Both PtPd/MWCNTs and PtIr/MWCNTs assemblies catalyzed the electrochemical oxidation of H(2)O(2). Cyclic voltammetry characterization measurements revealed that both the PtM (M=Pd, Ir)/MWCNTs/GCE possessed similar electrochemical surface areas (～0.55 cm(2)), and electron transfer rate constants (～1.23 × 10(-3)cms(-1)); however, the PtPd sensor showed a better performance in H(2)O(2) sensing than did the PtIr counterpart. Explanations were sought from XAS measurements to explain the reasons for differences in sensor activity. When applied to the electrochemical detection of H(2)O(2), the PtPd/MWCNTs/GC electrode exhibited a low detection limit of 1.2 μM with a wide linear range of 2.5-125 μM (R(2)=0.9996). A low working potential (0V (SCE)), fast amperometric response (<5s), and high sensitivity (414.8 μA mM(-1)cm(-2)) were achieved at the PtPd/MWCNTs/GC electrode. In addition, the PtPd/MWCNTs nanocatalyst sensor electrode also exhibited excellent reproducibility and stability. Along with these attractive features, the sensor electrode also displayed very high specificity to H(2)O(2) with complete elimination of interference from UA, AA, AAP and glucose.