Synthesis and antiamoebic activity of new cyclooctadiene ruthenium(II) complexes with 2-acetylpyridine and benzimidazole derivatives

Reaction of [Ru(eta4-C8H12) (CH3CN)2 Cl2] with 2-(2-pyridyl) benzimidazole or Schiff bases derived from 2-acetylpyridine and S-methyldithiocarbazate, S-benzyldithiocarbazate and thiosemicarbazide leads to form new complexes of the type [Ru(eta4-C8H12)(L)Cl2] (where L=ligand). In vitro, most of the compounds exhibited potent activity and the Ru derivatives 1a [Ru(eta4-C8H12)(2-Acpy-SMDT)Cl2], 2a [Ru(eta4-C8H12)(2-Acpy-SBDT)Cl2] and 3a [Ru(eta4-CsH12)(2-Acpy-TSC)Cl2] were found more active than metronidazole against (HK-9) strain of Entamoeba histolytica.     

Synthesis, characterisation and antiamoebic activity of new thiophene-2-carboxaldehyde thiosemicarbazone derivatives and their cyclooctadiene Ru(II) complexes

Reaction of new thiosemicarbazones (1-4) derived from thiophene-2-carboxaldehyde and cycloalkylaminothiocarbonylhydrazine with [Ru(eta(4)-C8H12)(CH3CN)2Cl2] leads to form complexes (1a-4a) of the type [Ru(eta(4)-C8H12)(TSC)Cl2] (where TSC=thiosemicarbazone). All the compounds have been characterised by elemental analysis, IR, 1H NMR, electronic spectra and thermogravimetric analysis. It is concluded that the thionic sulphur and the azomethine nitrogen atom of the ligands are bonded to the metal ion. In vitro antiamoebic screening against (HK-9) strain of Entamoeba histolytica indicated that the Ru(II) complexes of thiophene-2-carboxaldehyde thiosemicarbazones were found more active than the thiosemicarbazones.     

Spectrofluorimetric determination of vitamin B1 using horseradish peroxidase as catalyst in the presence of hydrogen peroxide

In this work a new spectrofluorimetric method for the determination of vitamin B₁, based on the catalytic activity of horseradish peroxidase (HRP) in the presence of hydrogen peroxide (H₂O₂), has been developed. Non‐fluorescent vitamin B₁ was easily converted through catalytic oxidation in alkaline medium into a fluorescent compound, even without exposure to light. The linear range for vitamin B₁ observed was 0.026–16.83 µg/mL (RSD = 1.75%). The correlation coefficient for the calibration curve and limit of detection were found to be 0.9964 and 0.015 µg/mL, respectively. The developed method is practical, simple, sensitive and relatively free from interference by coexisting substances and has been successfully applied for the determination of vitamin B₁ in pharmaceutical preparations. Copyright © 2008 John Wiley & Sons, Ltd.     

New Method for Counting Bacteria Associated with Coral Mucus

The ability to count bacteria associated with reef-building corals in a rapid, reliable, and cost-effective manner has been hindered by the viscous and highly autofluorescent nature of the coral mucus layer (CML) in which they live. We present a new method that disperses bacterial cells by trypsinization prior to 4′,6-diamidino-2-phenylindole (DAPI) staining and quantification by epifluorescence microscopy. We sampled seawater and coral mucus from Porites lobata from 6 reef sites influenced by wastewater intrusion and 2 reef sites unaffected by wastewater in Hawaii. Bacterial and zooxanthella abundances and cell sizes were quantified for each sample. Bacteria were more abundant in coral mucus (ranging from 5.3 × 10⁵ ± 1.0 × 10⁵ cells ml⁻¹ to 1.8 × 10⁶ ± 0.2 × 10⁶ cells ml⁻¹) than in the surrounding seawater (1.9 × 10⁵ ± 0.1 × 10⁵ cells ml⁻¹ to 4.2 × 10⁵ ± 0.2 × 10⁵ cells ml⁻¹), and the mucus-associated cells were significantly smaller than their seawater counterparts at all sites (P < 0.0001). The difference in cell size between mucus- and seawater-associated bacteria decreased at wastewater-influenced sites, where simultaneously mucus bacteria were larger and seawater bacteria were smaller than those at uninfluenced sites. The abundance of zooxanthellae in mucus ranged from 1.1 × 10⁵ ± 0.1 × 10⁵ cells ml⁻¹ to 3.4 × 10⁵ ± 0.3 × 10⁵ cells ml⁻¹. The frequency of dividing cells (FDC) was higher in the surrounding seawater than in mucus, despite finding that a 1,000-fold-higher zooxanthella biovolume than bacterial biovolume existed in the CML. Establishment of a standardized protocol for enumeration will provide the field of coral microbial ecology with the urgently needed ability to compare observations across studies and regions.The extremely viscous and highly autofluorescent nature of coral mucus has been a major challenge in developing enumeration techniques and has limited our ability to study the ecological interactions among coral mucus layer (CML)-associated microbial communities. Only a few studies have used direct counts to quantify bacteria in the CML, and the methods and subsequent results vary widely. The techniques have included scanning electron microscopy (SEM) (34), phase-contrast microscopy (27), and epifluorescent microscopy using a variety of stains (acridine orange staining [8], SYBR gold [20], and 4′,6-diamidino-2-phenylindole [DAPI] [3]). Bacterial abundances reported from these studies spanned more than 5 orders of magnitude (from 1.6 × 10² cells [cm²]⁻¹ using acridine orange [8] to 6.2 × 10⁷ cells [cm²]⁻¹ using SYBR gold [20]), and some of the studies are difficult to compare to each other because different units were used, such as cells ml⁻¹ of mucus and cells (cm²)⁻¹ of coral. Some variation in abundance is likely due to differences in mucus sampling methods and differences among coral species. However, the enormous quantity of autofluorescence emitted in green and red wavelengths found in most coral species creates a substantial challenge for reliably counting fluorescently stained cells in that portion of the spectrum, because many of the particles are bacterium sized. Many of these same particles could be visible with phase-contrast microscopy as well. Thus far, researchers quantifying CML-associated bacteria using epifluorescence microscopy have prepared their samples by following well-established protocols that were developed for seawater. We suggest that the viscous and autofluorescent nature of coral mucus may require some modifications from standard seawater protocols for epifluorescence microscopy to be most effective.SEM is an alternative to fluorescence-dependent techniques. It has the advantage of acquiring images with sufficient detail to distinguish among particles and cells, but this method is time-consuming, visualizes only the surface of the sample, and is not widely available or affordable enough for it to be a standard field protocol. An additional limitation is that most studies that have employed SEM for CML observation have found bacteria to be too dispersed to count in a reasonable number of micrographs (8, 19).Here we present a new method that disperses bacterial cells by enzymatically digesting the mucus with trypsin (an adaptation of routine cellular biology cell line culture procedures) and subsequently staining the cells with DAPI for rapid quantification using epifluorescence microscopy. DAPI fluoresces in the blue end of the spectrum, and its emission does not overlap with the autofluorescence of the mucus samples. This method is rapid, uses reagents and equipment readily available in microbial ecology laboratories, and can provide necessary information for studies of the ecology of microbial cells associated with mucus. It may also be helpful for studies of other aquatic gel-associated microbial communities.This visualization capability revealed that bacteria living with the reef-building coral Porites lobata were significantly smaller than their water-associated counterparts and that this difference is reduced in reefs heavily influenced by anthropogenic impacts. There is only one other report that we are aware of that observed small bacterial cell size in mucus from corals (of the genus Fungia), but that study did not quantify cell size (34). Given that mucus is a carbon-rich environment (6, 11, 12, 18, 24, 25, 31), this discovery is counterintuitive. It highlights questions regarding the ecological interactions that must occur in situ to select for small cell size in such a rich environment (3, 4, 7, 8, 11, 25, 34).     

Structure-activity relationship study between Ornithyl-Proline and Lysyl-Proline based tripeptidomimics as angiotensin-converting enzyme inhibitors

A designed library of tripeptidomimics of Ornithyl-Proline (Orn-Pro) and Lysyl-Proline (Lys-Pro) conjugated with various unnatural amino acids and carboxylic acid derived heterocyclics was synthesized and screened for possible inhibitors of angiotensin-converting enzyme (ACE). Among the tripeptidomimics 10[MTP-Orn-Pro], 11[HTP-Orn-Pro], 14[TA-Orn-Pro] and 20[BPA-Orn-Pro] showed prominent inhibition with IC50 values in micromolar concentrations. Structure-activity relationship study indicated that C3 side chain of Orn as compared to C4 side chain of Lys at P1' position was better suited to inhibit ACE, with propionic acid (C3) derived heterocyclics and unnatural amino acids.     

Structure–activity relationships of mononuclear metal–thiosemicarbazone complexes endowed with potent antiplasmodial and antiamoebic activities

A useful concept for the rational design of antiparasitic drug candidates is the complexation of bioactive ligands with transition metals. In view of this, an investigation was conducted into a new set of metal complexes as potential antiplasmodium and antiamoebic agents, in order to examine the importance of metallic atoms, as well as the kind of sphere of co-ordination, in these biological properties. Four functionalized furyl-thiosemicarbazones (NT1–4) treated with divalent metals (Cu, Co, Pt, and Pd) to form the mononuclear metallic complexes of formula [M(L)₂Cl₂] or [M(L)Cl₂] were examined. The pharmacological characterization, including assays against Plasmodium falciparum and Entamoeba histolytica, cytotoxicity to mammalian cells, and interaction with pBR 322 plasmid DNA was performed. Structure–activity relationship data revealed that the metallic complexation plays an essential role in antiprotozoal activity, rather than the simple presence of the ligand or metal alone. Important steps towards identification of novel antiplasmodium (NT1Cu, IC₅₀ of 4.6 μM) and antiamoebic (NT2Pd, IC₅₀ of 0.6 μM) drug prototypes were achieved. Of particular relevance to this work, these prototypes were able to reduce the proliferation of these parasites at concentrations that are not cytotoxic to mammalian cells.     

Oxidative Stress Parameters,Trace Elements,and Lipid Profile in Iranian Patients with Gaucher Disease

Biological Trace Element Research - Gaucher disease (GD) is most frequent disorder of glycolipid storage. The glucosylceramide accumulation might lead to oxidative stress and changes in lipid...     

Association of a variant in the tumor necrosis factor alpha gene with risk of cervical cancer

Molecular Biology Reports - Tumor necrosis factor alpha (TNF-α) is a pro-inflammatory cytokine involved in the regulation of the immune system and potentially the progression of cervical...     

Exercise Improved the Anti-Epileptic Effect of Carbamazepine through GABA Enhancement in Epileptic Rats

Neurochemical Research - Carbamazepine (CBZ) is an anticonvulsant drug that usually is used for the treatment of seizures. The anti-epileptic and the anti-epileptogenic effect of exercise has been...     

Anticholinesterase activity of some major intermediates in carbacylamidophosphate synthesis: Preparation,spectral characterization and inhibitory potency determination

Carbacylamidophosphates with the general formula RC(O)NHP(O)R₁R₂ constitute organophosphorus compounds that are used as insecticides, pesticides and ureas inhibitors. In this work, we studied the inhibition potency of CCl₃C(O)NHP(O)Cl₂1, CHCl₂C(O)NHP(O)Cl₂2, CH₂ClC(O)NHP(O)Cl₂3 and CF₃C(O)NHP(O)Cl₂4, which are the major intermediates for carbacylamidophosphates synthesis towards human erythrocyte acetylcholinesterase (hAChe) activity using Ellman's modified kinetic method. Unexpectedly, it was observed that they were not only hydrolytically unstable but also inhibited hAChE in a similar manner to that produced by organophosphorus insecticides. Enzymatic data, bimolecular inhibition rate constants (k_i) and IC₅₀ values for inhibition of hAChE demonstrated that they are irreversible inhibitors and the inhibition potency of compound 2 (IC₅₀ = 88 μM) was the greatest in comparison with compounds 1, 3 and 4. Also the electropositivity of the phosphorus atom and the hydrophobicity of the compounds demonstrated that these two factors play an additional effect and different role in the inhibitory activity of these compounds. Hydrolytic stability of the compounds was determined by ³¹P NMR monitoring of the loss of the parent molecules with D₂O as a function of time. This study considers antiacetylcholinesterase activity according to the structural and the electronic aspects of compounds 1–4, according to IR, ¹H, ¹³C and ³¹P NMR spectral data.