In vitro antimicrobial activity of a dehydroacetic acid and p-chlor-m-xylenol combination.
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Acetates↗
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The effect of sodium N-lauroyl sarcosinate and of sodium dehydroacetate on the enzymes of the gastrointestinal tract.
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Acetates↗
A novel approach to biodegradable block copolymers of epsilon-caprolactone and delta-valerolactone catalyzed by new aluminum metal complexes.
The chemical preparation of structurally well-defined biodegradable amphiphilic block copolymers is now of great interest for biomedical applications and the fundamental mimetic study of biomacromolecule self-assembly. For this purpose, in this study, (R,R)-N,N'-bis(3-tert-butylsalicylidene)-1,2-cyclohexanediamine 2 as a ligand was first synthesized from 1,2-cyclohexanediamine (DACH) and was allowed to further react with AlMe3, leading to a precursor compound 3. Then, the novel five-coordinated aluminum metal complexes 4-6 and 7-8 were prepared with good yields of 80-90%, bearing various molar mass monofunctional methoxy-poly(ethylene glycol) MPEG and difunctional poly(ethylene glycol) PEG as the alkoxy moieties, respectively. By means of nuclear magnetic resonance spectrometry (NMR), mass spectrometry (MALDI-FTMS) and Fourier Transform infrared spectrometry (FT-IR), new metal aluminum complexes 4-8 were characterized as having distinct chemical structures. Utilizing the synthesized metal complexes 4-8 as novel coordination polymerization catalytic templates, biodegradable amphiphilic MPEG-b-PCL, MPEG-b-PVL, PCL-b-PEG-b-PCL and PVL-b-PEG-b-PVL were synthesized with good control of the molecular weight distribution via the ring opening polymerization of epsilon-caprolactone and delta-valerolactone monomers at 100 degrees C in toluene. In addition, the chemical and crystalline structures and the thermal properties of these block biodegradable copolymers were analyzed by means of NMR, gel permeation chromatography (GPC), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). It was found that the melting points and crystallinities of the block copolymers synthesized strongly depended on the molecular structures of the polyether and polyester building blocks. Only one glass transition stage was detected, indicating good chain/segmental miscibility between the hydrophilic MPEG/PEG and hydrophobic PCL/PVL blocks in the non-crystalline regions. Moreover, TGA analysis exhibited typical two-step decomposition profiles with the weight-loss percentages in good agreement with block compositions from NMR calculations.
Aluminum↗
New biodegradable amphiphilic block copolymers of epsilon-caprolactone and delta-valerolactone catalyzed by novel aluminum metal complexes. II. Micellization and solution to gel transition.
In our previous study [J. Yang, L. Jia, L. Yin, J. Yu, Z. Shi, Q. Fang, A. Cao, Macromol. Biosci. 2004, 4, 1092.], new biodegradable copolymers of diblock methoxy poly(ethylene glycol)-block-poly(epsilon-caprolactone) and methoxy poly(ethylene glycol)-block-poly(delta-valerolactone), and triblock poly(epsilon-caprolactone)-block-poly(ethylene glycol)-block-poly(epsilon-caprolactone) and poly(delta-valerolactone)-block-poly(ethylene glycol)-block-poly(delta-valero-lactone) bearing narrow molecular weight distributions and well-defined block architectures were reported to be prepared with our original aluminum metal complex templates. This work will continue to report new investigations on their water solubility, and reversible thermal responsive micellization and solution to gel transition in distilled water. Among the new synthesized copolymers (P1-P23), seven diblock or triblock samples (P3, P6, P7, P11, P12, P19, and P21) with higher hydrophilic building block populations were revealed to be water soluble under ambient temperature. By means of UV spectrophotometer attached with a thermostat, important parameters as critical micellization mass concentrations (CMCs) and critical micellization temperatures (CMTs) were characterized for these new amphiphile dilute aqueous solution with the aid of an lipophilic organic dye probe of 1,6-diphenyl-1,3,5-hexatriene (DPH). Furthermore, the critical gelation temperatures (CGTs) were simultaneously investigated for these water-soluble block copolymers via a tube tilting method. It was found that the CMC, CMT, and CGT were strongly affected by the population and nature of the hydrophobic building blocks, and a higher hydrophobicity of the new amphiphilic block copolymer finally led to lower CMC and CMT, and higher CGT. In addition, the salts of KBr and NaCl were found to play as a salt-out effect on the solution to gel transition for the diblock P6 and triblock P11, exhibiting an interesting tunable gelation temperature close to 35-42 degrees C. These results will pave new possibility for the synthesized block structural amphiphiles as potential biomaterials to be applied in vivo.
Alum Compounds↗
GABA receptor agonists: pharmacological spectrum and therapeutic actions.
From the data discussed in this review it appears that GABA receptor agonists exhibit a variety of actions in the central nervous system, some of which are therapeutically useful (Table V). GABA receptor agonists, by changing the firing rate of the corresponding neurons accelerate noradrenaline turnover without changes in postsynaptic receptor density and diminish serotonin liberation with an up-regulation of 5HT2 receptors. These effects differ from those of tricyclic antidepressants which primarily block monoamine re-uptake and cause down-regulation of beta-adrenergic and 5HT2 receptors. The GABA receptor agonist progabide has been shown to exert an antidepressant action which is indistinguishable from that of imipramine in patients with major affective disorders. The fact that: (a) GABA receptor agonists and tricyclic antidepressants affect noradrenergic and serotonergic transmission differently; and (b) tricyclic antidepressants alter GABA-related parameters challenges the classical monoamine hypothesis of depression and suggests that GABA-mediated mechanisms play a role in mood disorders. Decreases in cellular excitability produced by GABAergic stimulation leads to control of seizures in practically all animal models of epilepsy. GABA receptor agonists have a wide spectrum as they antagonize not only seizures which are dependent on decreased GABA synaptic activity but also convulsant states which are apparently independent of alterations in GABA-mediated events. These results in animals are confirmed in a wide range of human epileptic syndromes. GABA receptor agonists decrease dopamine turnover in the basal ganglia and antagonize neuroleptic-induced increase in dopamine release. On repeated treatment, progabide prevents or reverses the neuroleptic-induced up-regulation of dopamine receptors in the rat striatum and antagonizes the concomitant supersensitivity to dopaminomimetics. Behaviorally, GABA receptor agonists diminish the stereotypies induced by apomorphine or L-DOPA suggesting that GABAergic stimulation results also in an antidopaminergic action which is exerted beyond the dopamine synapse. These effects of GABA receptor agonists may represent the basis of the antidyskinetic action of these compounds which, however, remains to be fully confirmed. GABA receptor agonists reduce striatal acetylcholine turnover, an effect which occurs at doses much lower than those which affect dopamine neurons. Since hyperactivity of cholinergic neurons plays a determinant role in the pathogenesis of some parkinsonian symptoms, it is conceivable that GABAergic stimulation is effective in ameliorating Parkinson's disease.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Toxicological evaluation of red mould rice.
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Citrinin↗
1H and 13C NMR identification of unexpected 3,4-dihydroquinoxalines in the syntheses of 1,5-benzodiazepine derivatives.
The reaction between o-phenylenediamines, dehydroacetic acid and aromatic aldehydes is shown to give not only the expected 1,5-benzodiazepine derivative but also a 3,4-dihydroquinoxaline, the structure of which was determined by its 1H and 13C 1D and 2D NMR spectra.
Aldehydes↗
Complete 1H and 13C NMR assignments of aurasperone A and fonsecinone A, two bis-naphthopyrones produced by Aspergillus aculeatus.
Complete assignments of 1H and 13C NMR chemical shifts of the polyketides aurasperone A and fonsecinone A were made by means of nuclear Overhauser enhancement and heteronuclear NMR correlation experiments. These compounds were isolated for the first time from Aspergillus aculeatus, an endophytic fungus obtained from leaves of Melia azedarach(Meliaceae).
Aspergillus↗
Structure elucidation and total synthesis of a unique group of trace impurities in Tipranavir drug product.
Four unknown trace impurities (7-10) were observed in the capsule formulation of the HIV drug Tipranavir after prolonged storage at 30 degrees C/70% RH. Extensive NMR and LC/MS analyses revealed the compounds to be covalent adducts between TRIS, an excipient of the formulation, and diastereomeric Tipranavir alcohols formed via slow air oxidation of the drug substance. The structures were ultimately confirmed by total synthesis with final purification by chiral, preparative supercritical fluid chromatography. A novel Favorskii rearrangement to furnish butyrolactones was also uncovered during the synthesis.
Alcohols↗
Application of centrifugal force to the extraction and separation of parasorboside and gerberin from Gerbera hybrida.
A method for the separation of parasorboside and gerberin from the ornamental plant Gerbera hybrida (Asteraceae) has been developed. The two closely related glucosides were extracted using an Extrachrom instrument, a prototype multi-functional separation tool equipped with an extraction chamber. The rotation planar extraction procedure was compared with that of a medium pressure solid-liquid extraction system. The resulting extracts were pre-purified using rotation planar chromatography and the results compared with those obtained using medium pressure liquid chromatography with silica gel as the stationary phase and a mobile phase of methanol:ethyl acetate:tetrahydrofuran at selectivity point Ps = 111 with 1% formic acid as modifier. The title compounds were isolated from the purified extracts by TLC and their structures confirmed by 1H- and 13C-NMR spectroscopy.
Asteraceae↗
High-performance liquid chromatography-coordination ion spray-mass spectrometry (HPLC-CIS/MS): a new tool for the analysis of non-polar compound classes in plant extracts using the example of Piper methysticum Forst.
An efficient method to characterise complex plant extracts is described using the example of Piper methysticum Forst. (kava; Piperaceae). The method is based on the on-line coupling of high-performance liquid chromatography to a new detection technique: coordination ion spray-mass spectrometry (CIS/MS). CIS/MS is a universal, novel ionisation technique improving selectivity as well as sensitivity. Charged complexes were formed through addition of central complexing ions such as sodium, silver and cobalt. The advantages of CIS/MS detection compared with the electrospray ionisation detection are discussed. The experimental set-up and the application of this simple and robust technique is described to show the its various fields of application in the analysis of plant extracts.
Chromatography, High Pressure Liquid↗
An HPLC-PAD method to analyse flavonoid glycosides and styrylpyrones from Cryptocarya species (Lauraceae).
An HPLC-PAD method has been developed in order to evaluate simultaneously the main secondary metabolites, flavonoid glycosides and styrylpyrones, of leaves of Cryptocarya moschata. The sample preparation, consisting of extraction, liquid-liquid extraction and centrifugation, requires minimum sample manipulation but produces high yields with reproducibility, selectivity and simplicity. HPLC on a C18 column presents each class of metabolites grouped and with good resolution of the main compounds. The experimental conditions can be used to study inter- and intra-specific variability of secondary metabolites in Cryptocarya spp.
Chromatography, High Pressure Liquid↗
Superheated water chromatography-nuclear magnetic resonance spectroscopy of kava lactones.
Three kava lactone constituents of Piper methysticum, namely, kawain, methysticin and desmethoxyyangonin, have been separated and identified by reversed-phase HPLC using superheated deuterium oxide as the mobile phase and on-line 1H-NMR detection. The method avoids the use of organic solvents in the mobile phase and hence interferences in the NMR analysis are minimised.
Chromatography, High Pressure Liquid↗
The structural elucidation of a novel iridoid derivative from Tachiadenus longiflorus (Gentianaceae) using the LSD programme and quantum chemical computations.
Oleanolic acid, scoparone, scopoletin and a novel iridoid derivative, angelone, were isolated from Tachiadenus longiflorus (Gentianaceae). The structure of angelone was determined from NMR data, given as input to the Logic for Structure Determination Programme, and was finally confirmed by comparison of experimental 13C-NMR chemical shifts with those obtained by quantum mechanical calculations.
Gentianaceae↗
Activity against plant pathogenic fungi of phomalactone isolated from Nigrospora sphaerica.
Phomalactone, 5,6-dihydro-5-hydroxy-6-prop-2-enyl-2H-pyran-2-one, produced by the fungus Nigrospora sphaerica, was tested in vitro against nine plant pathogenic fungi, and specifically inhibited the mycelial growth of Phytophthora infestans, with an MIC value of 2.5 mg litre-1. Its inhibitory activities against sporangium and zoospore germination of P infestans were similar to those against Phytophthora capsici. In vivo, at 100 and 500 mg litre-1, it reduced the development of tomato late blight caused by P infestans.
Ascomycota↗
Cytotoxicity and antimicrobial activity of goniothalamin isolated from Bryonopsis laciniosa.
The cytotoxicity and antimicrobial activity of goniothalamin isolated from Bryonopsis laciniosa was investigated. Goniothalamin showed potent cytotoxicity with LC50 values (5.03 microg/mL) comparable with the reference standard agent, gallic acid. It also showed weak antibacterial and significant antifungal activity against a wide range of gram positive and gram negative bacteria and fungi. The antibacterial (minimum inhibitory concentration) effect against Bacillus cereus and Shigella shiga was found to be 64 microg/mL.
Animals↗
Potential immunosuppressive and antiinflammatory activities of Malaysian medicinal plants characterized by reduced cell surface expression of cell adhesion molecules.
In the search for agents effective against immune-mediated disorders and inflammation, we have screened Malaysian medicinal plants for the ability to inhibit the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on the surface of murine endothelial cells (F-2), and mouse myeloid leukaemia cells (M1), respectively. Of 41 kinds (29 species, 24 genera, 16 families) of Malaysian plants tested, 10 and 19 plant samples significantly downregulated the expression of ICAM-1 and VCAM-1, respectively. Bioassay-directed fractionation of an extract prepared from the bark of Goniothalamus andersonii showed that its ingredients, goniothalamin (1) and goniodiol (2) inhibited the cell surface expression of both ICAM-1 and VCAM-1. The present results suggest that Malaysian medicinal plants may be abundant natural resources for immunosuppressive and antiinflammatory substances.
Animals↗
Effects of Gentiana lutea ssp. symphyandra on the central nervous system in mice.
A methanolic extact of Gentiana lutea ssp. symphyandra roots has been investigated for its possible effects on the central nervous system of mice. At doses of 250 and 500 mg/kg (i.p.), the methanol extract of Gentiana roots caused a significant increase in the swimming endurance test and exhibited slight analgesic activity, but no lethality in mice suggesting some activity on the central nervous system. However, there was no indication of sedation or muscular fatigue at the doses employed. HPLC analysis showed that three secoiridoid compounds, gentiopicroside, swertiamarine and sweroside were present and may have been responsible for the CNS effects of the methanol extract of Gentiana lutea ssp. symphyandra roots.
Analgesics↗