Action of alkyl cations and the natural ATPase inhibitor from mitochondria on soluble mitochondrial ATPase

The effect of the natural ATPase inhibitor and octylguanidine on the ATPase activity of soluble oligomycin-insensitive mitochondrial F₁ were compared. Both compounds induced a maximal inhibition of 60–80% in various preparations of F₁ studied. The inhibition was of the uncompetitive type with respect to MgATP, and the action of the compounds was partially additive. The data suggest that octylguanidine reproduces the action of the natural ATPase inhibitor. Alkylammonium salts also affect the ATPase activity in a similar form. F₁ bound to Sepharose-hexylammonium is largely inactive, whilst free hexylammonium at higher concentrations induces only a partial inhibition of the activity. This suggests that the degree of immobilization of F₁ is related to the magnitude of inhibition of ATPase activity induced by alkyl cations. The binding of F₁ to Sepharose-hexylammonium is prevented by high concentrations of Na⁺ or K⁺.     

Anthraquinones from Hedyotis capitellata

Four new furanoanthraquinones, 2-hydroxymethyl-3,4-[2'-(1-hydroxy-1-methylethyl)-dihydrofurano]-8-hydroxyanthraquinone, 2-hydroxymethyl-3,4-[1'-hydroxy-2'-(1-hydroxy-1-methylethyl)-dihydrofurano]-8-hydroxyanthraquinone, 2-hydroxymethyl-3,4-[2'-1-hydroxy-1-methylethyl)-dihydrofurano]anthraquinone and 2-methyl-3,4-[2'-(1-hydroxy-1-methylethyl)-dihydrofurano] anthraquinone or capitellataquinone A-D and four known anthraquinones, rubiadin, anthragallol 2-methyl ether, alizarin 1-methyl ether and digiferruginol, together with scopoletin were isolated from the stems of Hedyotis capitellata Wall (Rubiaceae). Lucidin-3-O-beta-glucoside was isolated from the roots of the plant. Characterization of the new compounds was carried out by extensive NMR studies using FGCOSY, FGHMQC, FGHMBC and DEPT-135 in addition to other spectroscopic methods.     

Design and synthesis of new antitumor agents with the 1,7-epoxycyclononane framework. Study of their anticancer action mechanism by a model compound

This article describes the design, synthesis and biological evaluation of a new family of antitumor agents having the 1,7-epoxycyclononane framework. We have developed a versatile synthetic methodology that allows the preparation of a chemical library with structural diversity and in good yield. The synthetic methodology has been scaled up to the multigram level and can be developed in an enantioselective fashion. The study in vitro of a model compound, in front of the cancer cell lines HL-60 and MCF-7, showed a growth inhibitory effect better than that of cisplatin. The observation of cancer cells by fluorescence microscopy showed the presence of apoptotic bodies and a degradation of microtubules. The study of cell cycle and mechanism of death of cancer cells by flow cytometry indicates that the cell cycle arrested at the G₀/G₁ phase and that the cells died by apoptosis preferably over necrosis. A high percentage of apoptotic cells at the subG₀/G₁ level was observed. This indicates that our model compound does not behave as an antimitotic agent like nocodazole, used as a reference, which arrests the cell cycle at G₂/M phase. The interaction of anticancer agents with DNA molecules was evaluated by atomic force microscopy, circular dichroism and electrophoresis on agarose gel. The results indicate that the model compound has not DNA as a target molecule. The in silico study of the model compound showed a potential good oral bioavailability.     

Structural and mode of action studies on bio-active molecules

The technique of nuclear Overhauser effect difference spectroscopy allows the determination, from¹H nuclear magnetic resonance spectra, of those protons in a structure which are near in space to a selected, irradiated proton. The experiment is extremely powerful in the determination of structure in solution, and is sufficiently precise often to give stereochemical detail. The method was used in determination of the structures of the antibiotics of the teicoplanin complex (members of the vancomycin group), and the principles are briefly illustrated. Additionally, nuclear magnetic resonance pulse sequences can be used to edit¹³C spectra (separate the spectrum into four spectra, containing C, CH, CH₂, and CH₃ carbons), and this technique also aided the structure elucidation of the teicoplanin complex. Finally, it is emphasised that nuclear Overhauser effect difference spectroscopy can be used to determine the molecular details of drug binding sites, and an example is given.     

Single- and Multi-component Adsorption Equilibria in Bubble Separation of Organic Material

Investigations were conducted on the adsorption equilibrium between the air bubbles and some organic materials in waste water. Langmuir’s adsorption isotherm held for the adsorption of soluble or insoluble material in single-component solution or suspension, while the extended adsorption isotherm held in the multi-component system. Among organic materials tested, isoelectric protein coagula were most efficiently bubble-separated, although the efficiency of separation was greatly affected by the coexistence of soluble hydrophobic molecules due to competitive adsorption between coagulated protein and small hydrophobic molecules. Pretreatment was suggested of protein-rich waste water without the usual coagulants.     

Polyphenolic compounds in the fruits of Egyptian medicinal plants (Terminalia bellerica, Terminalia chebula and Terminalia horrida): Characterization, quantitation and determination of antioxidant capacities

Thirty-four polyphenolic substances in methanol extracts of the fruits of Terminalia bellerica, Terminalia chebula and Terminalia horrida, three plants used in Egyptian folk medicine, were initially identified by HPLC-ESI-MS and quantitated by analytical HPLC after column chromatography on Sephadex LH-20. After purification by semi-preparative HPLC the compounds were identified by their mass and fragmentation patterns using ESI-MS-MS. For several compounds detailed ¹H/¹³C NMR analysis at 600 MHz was performed. Two polyphenolics, namely 4-O-(4″-O-galloyl-α-l-rhamnopyranosyl)ellagic acid and 4-O-(3″,4″-di-O-galloyl-α-l-rhamnopyranosyl)ellagic acid were identified by NMR. Antioxidant capacities of the raw fruit extracts and the major isolated substances were determined using the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), oxygen radical absorbance capacity (ORAC) and ferric reducing ability of plasma (FRAP) in vitro assays and indicated that chebulic ellagitannins have high activity which may correlate with high potential as cancer chemopreventive agents. Therefore, further studies (metabolism, bioavailability and toxicity) of the polyphenolics in Terminalia species using preclinical models and in vivo human intervention trials are warranted.     

鉴定天然产物结构的利器——DEPT和各种2D NMR谱

本文概括性地介绍了DEPT技术和新近各种常用的二维核磁共振谱在天然产物结构鉴定中的应用以及相应的一些注意点     

Enzymatic synthesis of novel branched sugar alcohols mediated by the transglycosylation reaction of pullulan-hydrolyzing amylase II (TVA II) cloned from Thermoactinomyces vulgaris R-47

Transglycosylation reactions are useful for preserving a specific sugar structure during the synthesis of branched oligosaccharides. We have previously reported a panosyl unit transglycosylation reaction by pullulan-hydrolyzing amylase II (TVA II) cloned from Thermoactinomyces vulgaris R-47 (Tonozuka et al., Carbohydr. Res., 1994, 261, 157–162). The acceptor specificity of the TVA II transglycosylation reaction was investigated using pullulan as the donor and sugar alcohols as the acceptor. TVA II transferred the α-panosyl unit to the C-1 hydroxyl group of meso-erythritol, C-1 and C-2 of xylitol, and C-1 and C-6 of d-sorbitol. TVA II differentiated between the sugar alcohols’ hydroxyl groups to produce five novel non-reducing branched oligosaccharides, 1-O-α-panosylerythritol, 1-O-α-panosylxylitol, 2-O-α-panosylxylitol, 1-O-α-panosylsorbitol, and 6-O-α-panosylsorbitol. The Trp³⁵⁶→Ala mutant showed similar transglycosylation reactions; however, panose production by the mutant was 4.0–4.5-fold higher than that of the wild type. This suggests that Trp³⁵⁶ is important for recognizing both water and the acceptor molecules in the transglycosylation and the hydrolysis reaction.     

Novel O-antigen of Hafnia alvei PCM 1195 lipopolysaccharide with a teichoic acid-like structure

The lipopolysaccharide (LPS) of Hafnia alvei strain PCM 1195 was obtained by the hot phenol/water method. The O-specific polysaccharide was released by mild acidic hydrolysis and isolated by gel filtration. The structure of the O-specific polysaccharide was investigated by ¹H, ¹³C, and ³¹P NMR spectroscopy, MALDI-TOF MS, and GC-MS, accompanied by monosaccharide and methylation analysis. It was concluded that the O-specific polysaccharide is composed of a hexasaccharide repeating units interlinked with a phosphate group: {→4-α-d-Glcp-(1→3)-α-l-FucpNAc-(1→3)-[α-d-Glcp-(1→4)]-α-d-GlcpNAc-(1→3)-α-l-FucpNAc-(1→4)-α-d-Glcp-(1→P}_n.