Production of glucose and bioactive aglycone by chemical and enzymatic hydrolysis of purified oleuropein fromOlea Europea

Pure-grade oleuropein, a bitter, hypotensive, phenolic glucoside, was obtained from organic extracts of olive plant leaves by two Chromatographic steps. The purified compound was characterized by spectroscopic NMR and FAB-MS methods. The glucoside underwent chemical and enzymatic hydrolysis. Aglycone was characterized by spectroscopic methods (¹H-NMR and FAB-MS). Glucose was measured by enzymatic methods. The enzymatic hydrolysis of oleuropein was carried out by a soluble β-glucosidase. The reaction was characterized in terms of kinetic parameters, optimal pH value, activation energy, inhibition constant by glucose, and thermal stability. Preliminary experiments were also performed in a continuousflow ultrafiltration membrane reactor. The cut-off of the membrane was lower than the molecular-weight of the enzyme, thus determining β-glucosidase confinement within the reactor. Under these conditions, β-glucosidase had a good long-term stability. This is an encouraging result in view of possible industrial applications.     

Profiling isoflavone conjugates in root extracts of lupine species with LC/ESI/MSn systems

Extracts obtained from roots of three lupine species (Lupinus albus, L. angustifolius, L. luteus) were analysed using LC/UV and LC/ESI/MS(n). The experiments were performed using two mass spectrometric systems, equipped with the triple quadrupole or ion trap analysers. Thirteen to twenty isomeric isoflavone conjugates were identified in roots of the investigated lupine species. These were di- and monoglycosides of genistein and 2'-hydroxygenistein with different patterns of glycosylation, both at oxygen and carbon atoms; some glycosides were acylated with malonic acid. It was not possible to establish the glycosylation sites of the aglycone only on the basis of the registered mass spectra; however, it was possible to differentiate C- and O-glucosides of isoflavones. Only comparison of retention times with those of standard compounds permitted to indicate the correct glycosylation pattern. In the case of diglycosides, the glycosylation pattern (O-diglucoside or O-glucosylglucoside) was distinguishable on the basis of the relative intensities of daughter ions in the mass spectra of protonated molecular ions. It was not possible to elucidate the site of malonylation on the sugar moiety from mass spectra, however, protonated molecules [M + H](+) of isoflavone glucosides with different placement of the malonyl group on the sugar ring were recognized in the extracts. In addition to the isoflavone glycosides, some flavone or flavonol glycosides were identified in the samples on the basis of collision-induced daughter ion spectra of the aglycone ions. A comparison of results obtained with the triple quadrupole and ion trap analysers was done in the course of the investigations.     

Synthesis of prospective disaccharide ligands for Escherichia coli O157 verotoxin

The synthesis of new potential ligands for Escherichia coli 0157 verotoxin is reported, based on disaccharide fragments of the tetrasaccharide glycan portion of Gb₄ glycolipid. Intramolecular aglycone delivery was employed for the high-yielding and stereoselective production of the azidopropyl-tethered α-galactoside building block.     

Study of the phenolic composition of spanish and italian monocultivar extra virgin olive oils: Distribution of lignans, secoiridoidic, simple phenols and flavonoids

The aim of the present study was to compare the phenolic content in selected monocultivar extra virgin olive oils. Analyses were carried out by HPLC/DAD/MS on Picual, Picuda, Arbequina and Hojiblanca oils from Spain and Seggianese and Taggiasca oils from Italy. Oils from cultivar Picual showed similar characteristics to those of Seggianese oils, with total amounts of secoiridoids of 498.7 and 619.2 mg/L, respectively. The phenolic composition of Arbequina oils is close to that of the Taggiasca variety with lignans among the main compounds. The determination of free and linked OH-Tyr, by way of an acid hydrolysis, represents a rapid and suitable method, especially when standards are not available, to determine antioxidant potentialities in terms of MPC, particularly for fresh extra virgin olive oils rich in secoiridoidic derivatives.     

Synthesis analogues of milbemycin and their bioactivity evaluation

<正>Eight new 13-O-aminocarbonylivermectin aglycones and 4'-O-aminocarbonylivermectin monosaccharide were synthesized from ivermectin agiycone and ivermectin monosaccharide by the selective protection of C_5-OH group.Their bioactivities were evaluated against spider mites(Tetranychus cinnabarimts),aphid(Aphis fabae) and oriental armyworm(Mytliimma sepatara). Their structures were confirmed by ~1H NMR.MS.     

Hydrogen‐Bond‐Mediated Aglycone Delivery (HAD): A Highly Stereoselective Synthesis of 1,2‐cis α‐D‐Glucosides from Common Glycosyl Donors in the Presence of Bromine

Described herein is the expansion of the picoloyl protecting‐group assisted H‐bond mediated aglycone delivery (HAD) method recently introduced by our laboratory. At first it was noticed that high α‐stereoselectivity is only obtained with S‐ethyl glycosyl donors and only in the presence of dimethyl(methylthio)sulfonium trifluoromethanesulfonate (DMTST), in high dilution, and low temperature. Combining the mechanistic studies of the HAD reaction and bromine‐promoted glycosylations allowed a very effective method to be devised that allows for highly stereoselective α‐glycosidation of practically all common leaving groups (S‐phenyl, S‐tolyl, S/O‐imidates) at regular concentrations and ambient temperature.     

Antimicrobial substances from the rare actinomycete Nonomuraea rhodomycinica NR4-ASC07T

Nonomuraea rhodomycinica NR4-ASC07^T is a rare actinomycete isolated from soil in Sirindhorn peat swamp forest. The crude extract of its culture broth exhibited antimicrobial and anticancer against diverse human pathogens and cancer cells. The chemical investigation of the crude extract led to the isolation of two new metabolites named nonomuric acid (1) and 3-hydroxy deoxydaunorubicinol aglycone (2), along with two known bioactive compounds [ε-rhodomycinone (3) and 7-deoxy-13-dihydrocarminomycinone (4)]. Compounds 1 and 3 showed antimalarial activity with the half maximal inhibitory concentration (IC₅₀) of 8.00 and 8.88 μg mL^?1, respectively. Compound 4 inhibited growth of Mycobacterium tuberculosis and Bacillus cereus at the minimum inhibitory concentrations of 50.0 and 12.50 μg mL^?1, respectively. Every compound exhibited cytotoxicity against cancer cells tested at IC₅₀ ≥ 6.34 μg mL^?1. These finding are the first report of bioactive metabolites produced by strain NR4-ASC07^T, suggesting that rare actinomycetes are yet promising sources for novel drug discovery.     

Gas Chromatographic and Mass Spectrometric Study of Trimethylsilyl Ethers of Cardiac Aglycones

Abstract

Cardenolides may be converted to volatile derivatives by silylation. Three levels of silylation have been defined. The use of HMDS-TMCS leads to TMSi ether formation for all relatively unhindered hydroxyl groups (3β, 12β, 16β). When BSA-TMCS is employed, the unsaturated lactone ring is converted to an enol form, with subsequent formation of a TMSi enol ether. All hydroxyl groups, including the tert. 14β-hydroxyl group and the enol derived from the lactone side chain, are converted to TMSi ethers with TSIM-BSA-TMCS at 60°. The derivatives have good gas chromatographic properties. Gas phase analytical methods can be used for the identification and characterization of these substances.     

Supercritical fluid chromatography as a tool for enantioselective separation; A review

Supercritical fluid chromatography (SFC) has become popular in the field of enantioselective separations. Many works have been reported during the last years. This review covers the period from 2000 till August 2013. The article is divided into three main chapters. The first one comprises a basic introduction to SFC. The authors provide a brief explanation of general principles and possibilities of this method. The advantages and drawbacks are also listed. Next part deals with chiral separation systems available in SFC, namely with the commonly used chiral stationary phases. Properties and interaction possibilities of the chiral separation systems are described. Recent theoretical papers are emphasized in this chapter. The last part of the paper gives an overview of applications of enantioselective SFC in analytical chemistry, in both analytical and preparative scales. Separation systems and conditions are summed up in tables so that they provide a helpful tool for analysts who search for a particular method of analysis.     

Synthesis of pennogenin utilizing the intact skeleton of diosgenin

Pennogenin (1) is an aglycone of bioactive com-ponents of Chinese traditional medicine named Chonglou(Paris),[1] which belongs to C-17-hy- droxyl-steroidal sapogenin. It is well known that Chonglou as well as the related herbs containing pennogenin and its glycosides have been used as haemostatic agents in clinic. They also exhibit antibi-otic and antitumor activity[1,2]. With the demand amount of Chonglou as well as the related drugs increasing while the plant resource decreasing day by day…