ESI(+)-MS and GC-MS study of the hydrolysis of N-azobenzyl derivatives of chitosan.

New N-p-chloro-, N-p-bromo-, and N-p-nitrophenylazobenzylchitosan derivatives, as well as the corresponding azophenyl and azophenyl-p-sulfonic acids, were synthesized by coupling N-benzylvchitosan with aryl diazonium salts. The synthesized molecules were analyzed by UV-Vis, FT-IR, 1H-NMR and 15N-NMR spectroscopy. The capacity of copper chelation by these materials was studied by AAS.

Partially acetylated chitooligosaccharides bind to YKL-40 and stimulate growth of human osteoarthritic chondrocytes.

Recent evidences indicating that cellular kinase signaling cascades are triggered by oligomers of N-acetylglucosamine (ChOS) and that condrocytes of human osteoarthritic cartilage secrete the inflammation associated chitolectin YKL-40, prompted us to study the binding affinity of partially acetylated ChOS to YKL-40 and their effect on primary chondrocytes in culture. Extensive chitinase digestion and filtration of partially deacetylated chitin yielded a mixture of ChOS (Oligomin™) and further ultrafiltration produced T-ChOS™, with substantially smaller fraction of the smallest sugars. YKL-40 binding affinity was determined for the different sized homologues, revealing micromolar affinities of the larger homologues to YKL-40.

Separation of isomeric disaccharides by traveling wave ion mobility mass spectrometry using CO2 as drift gas.

The use of CO(2) as a massive and polarizable drift gas is shown to greatly improve peak-to-peak resolution (R(p-p) ), as compared with N(2) , for the separation of disaccharides in a Synapt G2 traveling wave ion mobility cell. Near or baseline R(p-p) was achieved for three pairs of sodiated molecules of disaccharide isomers, that is, cellobiose and sucrose (R(p-p)  = 0.76), maltose and sucrose (R(p-p)  = 1.

Fast screening and secure confirmation of milk powder adulteration with maltodextrin via electrospray ionization-mass spectrometry [ESI(+)-MS] and selective enzymatic hydrolysis.

Direct-infusion electrospray ionization-mass spectrometry [ESI(+)-MS] of several milk powder samples, confiscated by the Brazilian Federal Police, showed ions accounting for sodiated and potassiated molecules of disaccharides (m/z 365 and 381) as well as trisaccharides (m/z 527 and 543), whereas monosaccharide ions were not detected. The trisaccharide ions were not detected in samples of genuine milk powder, raising the suspicion that their presence indicates adulteration by the addition of maltodextrin. In control samples, maltose and maltotriose were hydrolyzed by alpha-glucosidase and not beta-galactosidase, whereas lactose was resistant to alpha-glucosidase but was hydrolyzed with beta-galactosidase.

The effect of pH on the production of chitinolytic enzymes of Verticillium fungicola in submerged cultures.

Chitinase and N-acetylhexosaminidase activities in submerged cultures of Verticillium fungicola increased up to 5-fold and 2.5-fold, respectively when the pH of the culture medium was raised from 5 to 8. SDS-PAGE and zymograms of the freeze-dried crude enzyme obtained from the cultures indicated four chitin degrading proteins of M(w) 24, 40, 55 and 63 kDa, whereas isoelectric focusing displayed the separation of three chitin degrading enzymes with isoelectric points of 4.

Growth of phytopathogenic fungi in the presence of partially acetylated chitooligosaccharides.

Four phytopathogenic fungi were cultivated up to six days in media containing chitooligosaccharide mixtures differing in average DP and FA. The three different mixtures were named Q3 (which contained oligosaccharides of DP2-DP10, with DP2-DP7 as main components), Q2 (which contained oligosaccharides of DP2-DP12, with DP2-DP10 as main components) and Q1 (which derived from Q2 and contained oligomers of DP5-DP8 with hexamer and a heptamer as the main components). The novel aspect of this work is the description of the effect of mixtures of oligosaccharides with different and known composition on fungal growth rates.

Structural characterization of mesquite (Prosopis velutina) gum and its fractions.

Structural and physicochemical characteristics of mesquite gum (from Prosopis velutina) were investigated using FT-IR spectroscopic, mass spectrometric and chromatographic methods. Four fractions (F-I, F-IIa, F-IIb and F-III) were isolated by hydrophobic interaction chromatography. The samples were characterized and analyzed for their monosaccharide and oligomers composition by high performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD).

Joziknipholones A and B: the first dimeric phenylanthraquinones, from the roots of Bulbine frutescens.

From the roots of the African plant Bulbine frutescens (Asphodelaceae), two unprecedented novel dimeric phenylanthraquinones, named joziknipholones A and B, possessing axial and centrochirality, were isolated, together with six known compounds. Structural elucidation of the new metabolites was achieved by spectroscopic and chiroptical methods, by reductive cleavage of the central bond between the monomeric phenylanthraquinone and -anthrone portions with sodium dithionite, and by quantum chemical CD calculations. Based on the recently revised absolute axial configuration of the parent phenylanthraquinones, knipholone and knipholone anthrone, the new dimers were attributed to possess the P-configuration (i.

Quantitative sequencing of complex mixtures of heterochitooligosaccharides by vMALDI-linear ion trap mass spectrometry.

Heterochitooligosaccharides possess interesting biological properties. Isobaric mixtures of such linear heterochitooligosaccharides can be obtained by chemical or enzymatic degradation of chitosan. However, the separation of such mixtures is a challenging analytical problem which is so far unresolved.

Three ent-trachylobane diterpenes from the leaf exudates of Psiadia punctulata.

Three ent-trachylobane diterpenes have been isolated from the leaf exudates of Psiadia punctulata and characterised as 6alpha,17,19-ent-trachylobantriol; 2alpha,18,19-ent-trachylobantriol; and 2beta,6alpha,18,19-ent-trachylobantetraol. The structures were determined on the basis of spectroscopic evidence.

Antiplasmodial flavonoids from Erythrina sacleuxii.

The acetone extracts of the root bark and stem bark of Erythrina sacleuxii showed antiplasmodial activities against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum. Chromatographic separation of the acetone extract of the root bark afforded a new isoflavone, 7-hydroxy-4'-methoxy-3'-prenylisoflavone (trivial name 5-deoxy-3'-prenylbiochanin A) along with known isoflavonoids as the antiplasmodial principles. Flavonoids and isoflavonoids isolated from the stem bark of E.

Two unusual rotenoid derivatives, 7a-O-methyl-12a-hydroxydeguelol and spiro-13-homo-13-oxaelliptone, from the seeds of Derris trifoliata.

The crude methanol extract of the seeds of Derris trifoliata showed potent and dose dependent larvicidal activity against the 2nd instar larvae of Aedes aegypti. From this extract two unusual rotenoid derivatives, a rotenoloid (named 7a-O-methyl-12a-hydroxydeguelol) and a spirohomooxarotenoid (named spiro-13-homo-13-oxaelliptone), were isolated and characterised. In addition a rare natural chromanone (6,7-dimethoxy-4-chromanone) and the known rotenoids rotenone, tephrosin and dehydrodeguelin were identified.

Antimicrobial flavonoids from the stem bark of Erythrina burttii.

The chloroform extract of the stem bark of Erythrina burttii showed antifungal and antibacterial activities using the disk diffusion method. Flavonoids were identified as the active principles. Activities were observed against fungi and Gram(+) bacteria, but the Gram(-) bacteria Escherichia coli was resistant.

Size-controlled hydroxyapatite nanoparticles as self-organized organic-inorganic composite materials.

This paper presents some results concerning the size-controlled hydroxyapatite nanoparticles obtained in aqueous media in a biopolymer matrix from soluble precursors salts. Taking the inspiration from nature, where composite materials made of a polymer matrix and inorganic fillers are often found, e.g.

7a-O-methyldeguelol, a modified rotenoid with an open ring-C, from the roots of Derris trifoliata.

From the acetone extract of the roots of Derris trifoliata an isoflavonoid derivative, named 7a-O-methyldeguelol, a modified rotenoid with an open ring-C, representing a new sub-class of isoflavonoids (the sub-class is here named as rotenoloid), was isolated and characterised. In addition, the known rotenoids, rotenone, deguelin and alpha-toxicarol, were identified. The structures were determined on the basis of spectroscopic evidence.

Anti-plasmodial flavonoids from the stem bark of Erythrina abyssinica.

The ethyl acetate extract of the stem bark of Erythrina abyssinica showed anti-plasmodial activity against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum with IC(50) values of 7.9+/-1.1 and 5.

Structure of the D142N mutant of the family 18 chitinase ChiB from Serratia marcescens and its complex with allosamidin.

Catalysis by ChiB, a family 18 chitinase from Serratia marcescens, involves a conformational change of Asp142 which is part of a characteristic D(140)XD(142)XE(144) sequence motif. In the free enzyme Asp142 points towards Asp140, whereas it rotates towards the catalytic acid, Glu144, upon ligand binding. Mutation of Asp142 to Asn reduced k(cat) and affinity for allosamidin, a competitive inhibitor.

Interactions of a family 18 chitinase with the designed inhibitor HM508 and its degradation product, chitobiono-delta-lactone.

We describe enzymological and structural analyses of the interaction between the family 18 chitinase ChiB from Serratia marcescens and the designed inhibitor N,N'-diacetylchitobionoxime-N-phenylcarbamate (HM508). HM508 acts as a competitive inhibitor of this enzyme with a K(i) in the 50 microM range. Active site mutants of ChiB show K(i) values ranging from 1 to 200 microM, providing insight into some of the interactions that determine inhibitor affinity.

Effect of rotenoids from the seeds of Millettia dura on larvae of Aedes aegypti.

A crude chloroform extract of seeds of Millettia dura Dunn (Leguminosae) showed high activity (LC50 = 3.5 microg ml(-1) at 24 h) against second-instar larvae of the mosquito, Aedes aegypti L (Diptera: Culicidae). The rotenoids, deguelin and tephrosin, isolated from the seeds of this plant also showed potent activities, with LC50 values of 1.

Anti-plasmodial activities and X-ray crystal structures of rotenoids from Millettia usaramensis subspecies usaramensis.

The dichloromethane extract of the stem bark of Millettia usaramensis subspecies usaramensis showed anti-plasmodial activity against the chloroquine sensitive (D6) and chloroquine resistant (W2) strains of Plasmodium falciparum. Chromatographic separation of the extract led to the identification of a new rotenoid, (6aR,12aS)-2,3-methylenedioxy-9-methoxy-8-(3,3-dimethylallyl)-12a-hydroxyrotenoid (trivial name, usararotenoid C) along with known flavonoids (usararotenoid A, 12a-epimillettosin, 6a,12a-dehydromillettone, barbigerone and 4'-O-geranylisoliquiritigenin) as the anti-plasmodial principles. The structures were determined by spectroscopic analyses.

Flavonoids and isoflavonoids with antiplasmodial activities from the root bark of Erythrina abyssinica.

From the root bark of Erythrina abyssinica a new pterocarpene [3-hydroxy-9-methoxy-10-(3,3-dimethylallyl)pterocarpene] and a new isoflav-3-ene [7,4'-dihydroxy-2',5'-dimethoxyisoflav-3-ene] were isolated. In addition, the known compounds erycristagallin, licoagrochalcone A, octacosyl ferulate and triacontyl 4-hydroxycinnamate were identified. The structures were determined on the basis of spectroscopic evidence.

Two prenylated flavonoids from the stem bark of Erythrina burttii.

From the stem bark of Erythrina burttii, a new isoflavone, 5,2',4'-trihydroxy-7-methoxy-6-(3-methylbut-2-enyl)isoflavone (trivial name, 7-O-methylluteone) and a new flavanone, 5,7-dihydroxy-4'-methoxy-3'-(3-methylbutadienyl)-5'-(3-methylbut-2-enyl)flavanone (trivial name, burttinonedehydrate) along with three known isoflavonoids (8-prenylluteone, 3-O-methylcalopocarpin and genistein) were isolated. The structures were determined on the basis of spectroscopic evidence.

Solution- and bound-state conformational study of N,N',N"-triacetyl chitotriose and other analogous potential inhibitors of hevamine: application of trNOESY and STD NMR spectroscopy.

The solution-state conformations of N,N',N"-triacetyl chitotriose (1) and other potential chitinase inhibitors 2-4 were studied using a combination of NMR spectroscopy (NOESY) and molecular mechanics calculations. Determination solely of the global energy minimum conformation was found to be insufficient for an agreement with the NMR results. An appropriate consistency between the NMR experimental data and theoretical calculations was only reached by assessing the structures as population-weighted average conformers based on Boltzmann distributions derived from the calculated relative energies.

The influence of carrier and drug morphology on drug delivery from dry powder formulations.

Lactose was crystallised either from neutralised Carbopol 934 gel or from water-ethanol solution without stirring, with a view to obtaining lactose alpha-monohydrate of favourable shape and smooth surface, suitable for use as carriers in formulations for dry powder inhalers (DPIs). Crystallisation of salbutamol sulphate was carried out in the presence of water, lecithin and ethanol to form salbutamol crystals with defined shape and smooth surface. The crystals formed were needle-shaped, with a length of less than 6 microm and a width between 0.