Involvement of thromboxane A2 and tyrosine kinase in the synergistic interaction of platelet activating factor and calcium ionophore A23187 in human platelet aggregation

The present study was carried out to examine the mechanisms of the synergistic interaction of PAF and A23187 mediated platelet aggregation. We found that platelet aggregation mediated by subthreshold concentrations of PAF (5 nM) and A23187 (1 mM) was inhibited by PAF receptor blocker (WEB 2086, IC50 = 0.65 mM) and calcium channel blockers, diltiazem (IC50 = 13 mM) and verapamil (IC50 = 18 mM). Pretreatment of platelets with PAF and A23187 induced rise in intracellular calcium and this effect was also blocked by verapamil. While examining the role of the down stream signaling pathways, we found that platelet aggregation induced by the co-addition of PAF and A23187 was also inhibited by low concentrations of phospholipase C (PLC) inhibitor (U73122; IC50 = 10 mM), a cyclooxygenase inhibitor (indomethacin; IC50 = 0.2 mM) and inhibitor of TLCK, herbimycin A with IC50 value of 5 mM. The effect was also inhibited by a specific TXA2 receptor antagonist, SQ 29548 with very low IC50 value of 0.05 mM. However, the inhibitors of MAP kinase, PD98059 and protein kinase C, chelerythrine had no effect on PAF and A23187-induced platelet aggregation. These data suggest that the synergism between PAF and A23187 in platelet aggregation involves activation of thromboxane and tyrosine kinase pathways.     

Spectrophotometric Determination of Ondansetron Hydrochloride in Pharmaceutical Bulk and Dosage Forms

A rapid, simple and accurate spectrophotometric method is developed for the determination of ondansetron hydrochloride in pure and tablet formulations. The method depends on the charge‐transfer complexation between ondansetron base as n‐electron donor with chloranil as π‐acceptor to give a colored complex, which absorbs maximally at 470 nm. Beer's law is obeyed in the concentration ranges 70–980 μg mL^?1 with molar absorptivity of 4.47 × 10² L mole^?1 cm^?1. The proposed method is precise, accurate and specific for the quantitative determination of drug in bulk and tablet formulations.     

Preparation of novel,moisture-stable,Lewis-acidic ionic liquids containing quaternary ammonium salts with functional side chains

A range of novel, moisture-stable, Lewis-acidic ionic liquids has been prepared by mixing appropriate molar ratios of MCl2 (M = Zn and/or Sn) and quaternary ammonium salts of formula [Me3NC2H4Y]Cl (Y = OH, Cl, OC(O)Me, OC(O)Ph); the influence of substituent Y and metal M on the physical properties of the melts has been investigated.     

Synthesis of fluorinated 2,3-dihydropyran-4-ones by cyclocondensation of 1,3-dicarbonyl dianions with aldehydes

The reaction of the dianion of 1,1,1-trifluoro-pentane-2,4-dione with aldehydes and subsequent addition of hydrochloric acid afforded 2,3-dihydro-6-trifluoromethyl-pyran-4-ones. The reaction of the dianion of acetylacetone with fluorinated benzaldehydes gave the corresponding fluorinated 2-aryl-2,3-dihydro-6-methyl-pyran-4-ones. All reactions proceeded in very good yield and with very good regioselectivity.     

Synthesis,Self-assembly and Electrode Application of Mussel-inspired Alternating Copolymers

We reported the first mussel-inspired alternating copolymer with a high amount of catechol groups(50% molar ratio) through a facile epoxy-amino click reaction between 9,9-bis(4-(2-glycidyloxyethyl)phenyl fluorene(BGEPF) and dopamine(DA).The obtained copolymers were used to prepare carbon/nitrogen-doped α-Fe_2O_3 nanoparticles through self-assembly,coordination and calcination,which displayed excellent electrochemical performance as anode materials for Li-ion batteries.     

Development of 2,4-dinitrophenylhydrazine-modified carbon paste electrode for highly sensitive electrochemical sensing of amino acids

Monatshefte für Chemie - Chemical Monthly - Herein, a carbon paste electrode was modified with 2,4-dinitrophenylhydrazine (2,4-DNPHMCPE), for the first time, to sense the three amino acids...     

Site-selective Suzuki-Miyaura cross-coupling reactions of 2,3,4,5-tetrabromofuran

Suzuki-Miyaura reactions of 2,3,4,5-tetrabromofuran allow a convenient and site-selective synthesis of mono-, di- and tetraarylfurans which are not readily available by other methods.     

Canarene: a triterpenoid with a unique carbon skeleton from Canarium schweinfurthii

Canarene (1), a triterpene with an unprecedented carbon backbone, was isolated from Canarium schweinfurthii . It is the first member of a new class of triterpenoids, for which the name "canarane' is proposed. 1 showed weak α-glucosidase inhibitory activity, and its structure was unambiguously deduced by single-crystal X-ray diffraction.     

Effects of CuCl2��6H2O and ZnCl2��6H2O on the viscosity of aqueous ethanol mixtures

The effects of CuCl₂ and ZnCl₂ on the viscosity in aqueous ethanol mixtures (10%–50% v/v) were studied in the concentration range 1.0×10⁻²–8.0×10⁻² mol·dm⁻³ at different temperatures. It was found that the viscosities increased with an increase in the concentration of the salts and percent composition of ethanol content, whereas it decreased with an increase in temperature. Ion-ion and ion-solvent interactions are determined with the help of A- and B-coefficients of Jones-Dole equation. The values of A- and B-coefficients are irregular and increase with a rise in temperature and also with an increase in ethanol contents for both salts. Negative values of B-coefficients show that ion solvent interactions is comparatively small and suggest that CuCl₂ and ZnCl₂ behave as structure breakers in aqueous ethanol mixtures. Thermodynamic parameters like the energy of activation (E _η ) and change in entropy of activation (ΔS*) were also evaluated which confirm the structure breaker behavior of salts in aqueous ethanol mixtures.     

Potent anti-platelet constituents from Centaurea iberica

New naturally occurring nitrogenous compounds 1 and 2, along with a new dimeric lignan glucoside 3, have been isolated from the ethyl acetate soluble fraction of Centaurea iberica. Their structures have been elucidated through spectroscopic techniques. All the isolated compounds showed significant platelet aggregation inhibition.