Flavonoids and a naphthopyranone from Eriocaulon ligulatum and their mutagenic activity

A new acylated flavonoid, 6,4'-dimethoxyquereetin-3-O-beta-D-6 ''[3,4,5-trihydroxy (E)-cinnamoyl]glucopyranoside, and a naphthopyranone dimer, named eriocauline, together with 2 other known flavonoids, 6-methoxyapigenin-7-O-beta-D-glucopyranoside and 6-methoxyapigenin-7-O-beta-D-allopyranoside, have been isolated from the capitulae of Eriocaulon ligulatum. The compounds were identified using spectroscopic methods (HR-ESI-MS, and 1-D and 2-D NMR). The methanol extract exhibited mutagenic activity in the Salmonella/microsome assay, in strains TA100, TA97a and TA102 and for dichloromethane extract tested in strain TA98.

Preparative droplet counter-current chromatography for the separation of the new nor-seco-triterpene and pentacyclic triterpenoids from Qualea parviflora

The methanolic extract of the bark of the medicinal plant Qualea parviflora (Vochysiaceae) contains new nor-seco-triterpene and pentacyclic triterpenoids. They were separated in a preparative scale using droplet counter-current chromatography. The optimum solvent used was composed of a mixture of CHCl3/MeOH/H2O (43:37:20, v/v) in the descending mode and led to a successful separation of the new compound 28-nor-17, 22-seco-2 alpha, 3 beta, 19, 22, 23-pentahydroxy-Delta(12)-olecinane, besides the known triterpenoids bellericagenin B, bellericaside B and arjunglucoside I. Identification was performed by ESI-MS, H-1 NMR and C-13 NMR analyses.

The shielding effect of glycerol against protein ionization in electrospray mass spectrometry

Most commercial recombinant proteins used as molecular biology tools, as well as many academically made preparations, are generally maintained in the presence of high glycerol concentrations after purification to maintain their biological activity. The present study shows that larger proteins containing high concentrations of glycerol are not amenable to analysis using conventional electrospray ionization mass spectrometry (ESI-MS) interfaces. In this investigation the presence of 25% (v/v) glycerol suppressed the signals of Taq DNA polymerase molecules, while 1% (v/v) glycerol suppressed the signal of horse heart myoglobin. The signal suppression was probably caused by the interaction of glycerol molecules with the proteins to create a shielding effect that prevents the ionization of the basic and/or acidic groups in the amino acid side chains. To overcome this difficulty the glycerol concentration was decreased to 5% (v/v) by dialyzing the Taq polymerase solution against water, and the cone voltage in the ESI triple-quadrupole mass spectrometer was set at 80-130 V. This permitted observation of a mass spectrum that contained ions corresponding to protonation of up to 50% of the ionizable basic groups. In the absence of glycerol up to 85% of the basic groups of Taq polymerase became ionized, as observed in the mass spectrum at relatively low cone voltages. An explanation of these and other observations is proposed, based on strong interactions between the protein molecules and glycerol. For purposes of comparison similar experiments were performed on myoglobin, a small protein with 21 basic groups, whose ionization was apparently suppressed in the presence of 1% (v/v) glycerol, since no mass spectrum could be obtained even at high cone voltages. Copyright (C) 2003 John Wiley Sons, Ltd.

Multiple bradykinin-related peptlides from the capture web of the spider Nephila clavipes (Araneae, Tetragnatidae)

Three bradykinin-related peptides (nephilakinins-I to -III) and bradykinin itself were isolated from the aqueous washing extract of the capture web of the spider Nephila clavipes by gel permeation chromatography on a Sephacryl S-100 column, followed by chromatography in a Hi-Trap Sephadex-G25 Superfine column. The novel peptides occur-red in low concentrations and were sequenced through ESI-MS/MS analysis: nephilakinin-I (G-P-N-P-G-F-S-P-F-R-NH2), nephilakinin-Il (E-A-P-P-G-F-S-P-F-R-NH2) and nephilakinin-III (P-S-P-P-G-F-S-P-F-R-NH2)- Synthetic peptides replicated the novel bradykinin-related peptides, which were submitted to biological characterizations. Nephilakinins were shown to cause constriction on isolated rat ileum preparations and relaxation on rat duodenum muscle preparations at amounts higher than bradykinin; apparently these peptides constitute B-2-type agonists of ileal and duodenal smooth muscles. All peptides including the bradykinin were moderately lethal to honeybees. These bradykinin peptides may be related to the predation of insects by the webs of N. clauipes. (c) 2005 Elsevier B.V. All rights reserved.

Structural and functional characterization of two novel peptide toxins isolated from the venom of the social wasp Polybia paulista

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural and biological characterization of three novel mastoparan peptides from the venom of the neotropical social wasp Protopolybia exigua (Saussure)

The venom of the Neotropical social wasp Protopolybia exigua(Saussure) was fractionated by RP-HPLC resulting in the elution of 20 fractions. The homogeneity of the preparations were checked out by using ESI-MS analysis and the fractions 15, 17 and 19 (eluted at the most hydrophobic conditions) were enough pure to be sequenced by Edman degradation chemistry, resulting in the following sequences:Protopolybia MPI I-N-W-L-K-L-G-K-K-V-S-A-I-L-NH2 Protopolybia-MP II I-N-W-K-A-I-I-E-A-A-K-Q-A-L-NH2 Protopolybia-MP III I-N-W-L-K-L-G-K-A-V-I-D-A-L-NH2All the peptides were manually synthesized on-solid phase and functionally characterized. Protopolybia-MP I is a hemolytic mastoparan, probably acting on mast cells by assembling in plasma membrane, resulting in pore formation; meanwhile, the peptides Protopolybia-MP II and -MP III were characterized as a non-hemolytic mast cell degranulator toxins, which apparently act by virtue of their binding to G-protein receptor, activating the mast cell degranulation. (C) 2004 Elsevier Ltd. All rights reserved.

Structural and biological characterization of two novel peptides from the venom of the neotropical social wasp Agelaia pallipes pallipes

The venom of the neotropical social wasp Agelaia pallipes pallipes was fractionated by RP-HPLC resulting in the elution of seven fractions; the last two were re-fractionated under RP-HPLC by using isocratic elution conditions and the purity of the fractions were confirmed by using ESI-MS analysis. Both fractions are constituted of peptide components, which were sequenced by Edman degradation chemistry, resulting in the following sequences:Protonectin I-L-G-T-I-L-G-L-L-K-G-L-NH2Agelaia-MP I-N-W-L-K-L-G-K-A-I-I-D-A-L-NH2Both peptides are manually synthesized on solid-phase and functionally characterized by using Wistar rats cells. Protonectin is a non-hemolytic chemotactic peptide for polymorphonucleated leukocytes (PMNL), presenting some mast cell degranulating activity and potent antimicrobial action both against Gram-positive and Gram-negative bacteria. Agelaia-MP was characterized as a hemolytic mast cell degranulator toxin, presenting a poor antimicrobial action and no chemotaxis for PMNL. (C) 2004 Elsevier Ltd. All rights reserved.

Monitoring the positioning of short polycationic peptides in model lipid bilayers by combining hydrogen/deuterium exchange and electrospray ionization mass spectrometry

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Hydrogen/deuterium exchange mass spectrometry for characterizing phosphoenolpyruvate-induced structural transitions in Mycobacterium tuberculosis 5-enolpyruvylshikimate-3-phosphate synthase (EC 2.5.1.1)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural and functional characterization of N-terminally blocked peptides isolated from the venom of the social wasp Polybia paulista

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Venom peptide analysis of Vipera ammodytes meridionalis (Viperinae) and Bothrops jararacussu (Crotalinae) demonstrates subfamily-specificity of the peptidome in the family Viperidae

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phenolic Composition of the Brazilian Seedless Table Grape Varieties BRS Clara and BRS Morena

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nb-containing hematites Fe2-xNbxO3: The role of Nb5+ on the reactivity in presence of the H2O2 or ultraviolet light

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Photocatalyst TiO2-Co: the effect of doping depth profile on methylene blue degradation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Metabolite fingerprint of "capim dourado" (Syngonanthus nitens), a basis of Brazilian handcrafts

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)