Mutagenicity of paepalantine dimer and glycoside derivatives from Paepalanthus bromelioides

The first isocoumarin isolated from the methylene chloride extract of Paepalanthus bromelioides, named paepalantine (isocoumarin 1), was found to have antimicrobial activity; but, it is mutagenic clastogenic and cytotoxic. Two other isocoumarins, paepalantine-9-O-beta-D-glucopyranoside (isocoumarin 2) and paepalantine-9-O-beta-D-allopyranosyl(1-->6) glucopyranoside (isocoumarin 3) were isolated from the ethanolic extract. A fourth new isocoumarin, also isolated from the methylene chloride extract of the capitula of P. bromelioides, was characterized as an 8-8' dimer of paepalantine and denominated isocoumarin 4. The abilities of isocoumarins 2, 3 and 4 to induce mutations in Salmonella typhimurium strains TA97a, TA98, TA100 and TA102 were investigated. Mutagenic activity was observed in strain TA97a treated with isocoumarin 2 in the presence of S9 mixture. The substitution of H at position 9 by glucose or glucose-allose caused reductions in the mutagenic activities of paepalantine, indicating this to be an important site for these properties. (C) 2003 Elsevier Ltd. All rights reserved.

2-Bromo-1,4-naphthoquinone: a potentially improved substitute of menadione in Apatone therapy

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ghost free dual vector theories in 2+1 dimensions

We explore here the issue of duality versus spectrum equivalence in dual theories generated through the master action approach. Specifically we examine a generalized self-dual (GSD) model where a Maxwell term is added to the self-dual model. A gauge embedding procedure applied to the GSD model leads to a Maxwell-Chern-Simons (MCS) theory with higher derivatives. We show here that the latter contains a ghost mode contrary to the original GSD model. By figuring out the origin of the ghost we are able to suggest a new master action which interpolates between the local GSD model and a nonlocal MCS model. Those models share the same spectrum and are ghost free. Furthermore, there is a dual map between both theories at classical level which survives quantum correlation functions up to contact terms. The remarks made here may be relevant for other applications of the master action approach.

A new spin-2 self-dual model in D=2+1

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dual descriptions of spin-two massive particles in D=2+1 via master actions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Duality of parity doublets of helicity +/- 2 in D=2+1 dimensions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Unitarity of spin-2 theories with linearized Weyl symmetry in D=2+1 dimensions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Thermo-analyses of polyaniline and its derivatives

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Analysis of Bothrops jararacussu venomous gland transcriptome focusing on structural and functional aspects: I - gene expression profile of highly expressed phospholipases A(2)

Snake venom glands are a rich source of bioactive molecules such as peptides, proteins and enzymes that show important pharmacological activity leading to in local and systemic effects as pain, edema, bleeding and muscle necrosis. Most studies on pharmacologically active peptides and proteins from snake venoms have been concerned with isolation and structure elucidation through methods of classical biochemistry. As an attempt to examine the transcripts expressed in the venom gland of Bothrops jararacussu and to unveil the toxicological and pharmacological potential of its products at the molecular level, we generated 549 expressed sequence tags (ESTs) from a directional cDNA library. Sequences obtained from single-pass sequencing of randomly selected cDNA clones could be identified by similarities searches on existing databases, resulting in 197 sequences with significant similarity to phospholipase A(2) (PLA(2)), of which 83.2% were Lys49-PLA(2) homologs (BOJU-1), 0.1% were basic Asp49-PLA(2)s (BOJU-II) and 0.6% were acidic Asp49-PLA(2)s (BOJU-III). Adjoining this very abundant class of proteins we found 88 transcripts codifying for putative sequences of metalloproteases, which after clustering and assembling resulted in three full-length sequences: BOJUMET-I, BOJUMET-II and BOJUMET-III; as well as 25 transcripts related to C-type lectin like protein including a full-length cDNA of a putative galactose binding C-type lectin and a cluster of eight serine-proteases transcripts including a full-length cDNA of a putative serine protease. Among the full-length sequenced clones we identified a nerve growth factor (Bj-NGF) with 92% identity with a human NGF (NGHUBM) and an acidic phospholipase A2 (BthA-I-PLA(2)) displaying 85-93% identity with other snake venom toxins. Genetic distance among PLA(2)s from Bothrops species were evaluated by phylogenetic analysis. Furthermore, analysis of full-length putative Lys49-PLA(2) through molecular modeling showed conserved structural domains, allowing the characterization of those proteins as group II PLA(2)s. The constructed cDNA library provides molecular clones harboring sequences that can be used to probe directly the genetic material from gland venom of other snake species. Expression of complete cDNAs or their modified derivatives will be useful for elucidation of the structure-function relationships of these toxins and peptides of biotechnological interest. (C) 2004 Elsevier SAS. All rights reserved.

Comparison of the gastroprotective effect of a diterpene lactone isolated from Croton cajucara with its synthetic derivatives

The effect of three new derivatives from dehydrocrotonin (DHC-compound I) on gastric damage indifferent animal models including gastric ulceration induced by a necrotic agent and hypothermic restrained-stress was studied: compound 11 (produced by reducing the cyclohexenone moiety of DHC with NaBH4): compound III (produced by reducing the carbonyls with LiAlH4); and compound IV (produced by transforming the lactone moiety into an amide). Their structures were confirmed on the basis of chemical and physicochemical evidence. When previously administered (p.o.) at a dose of 100 mg/kg, compound II significantly (P < 0.01) reduced gastric injury induced by HCl/ethanol (78%) and indomethacin (88%) better than did reference compound 1 (48 and 43%, respectively). But the anti-ulcerogenic activity of compound II was completely abolished by the stress-induced ulcer. Reduction of carbonyls with LiAlH4 (compound 111) caused decreased activity, markedly when no protective effect in any of the models was applied (P > 0.05). However, compound IV, in which the lactone moiety was changed into an amide. when administered at the same dose (100 mg/kg, p.o.), was more effective. The presence of a lactone moiety or Michael acceptor is probably essential for the anti-ulcerogenic effect of these compounds. (C) 2003 Elsevier B.V. Ireland Ltd. All rights reserved.

Inequalities for zeros of associated polynomials and derivatives of orthogonal polynomials

It is well known and easy to see that the zeros of both the associated polynomial and the derivative of an orthogonal polynomial p(n)(x) interlace with the zeros of p(n)(x) itself. The natural question of how these zeros interlace is under discussion. We give a sufficient condition for the mutual location of kth, 1 less than or equal to k less than or equal to n - 1, zeros of the associated polynomial and the derivative of an orthogonal polynomial in terms of inequalities for the corresponding Cotes numbers. Applications to the zeros of the associated polynomials and the derivatives of the classical orthogonal polynomials are provided. Various inequalities for zeros of higher order associated polynomials and higher order derivatives of orthogonal polynomials are proved. The results involve both classical and discrete orthogonal polynomials, where, in the discrete case, the differential operator is substituted by the difference operator. (C) 2001 IMACS. Published by Elsevier B.V. B.V. All rights reserved.

Interfacial surface charge and free accessibility to the PLA(2)-active site-like region are essential requirements for the activity of Lys49 PLA(2) homologues

Lys49 phospholipase A(2) homologues are highly myotoxic and cause extensive tissue damage but do not display hydrolytic activity towards natural phospholipids. The binding of heparin, heparin derivatives and polyanionic compounds such as suramin result in partial inhibition (up to 60%) of the myotoxic effects due to a change in the overall charge of the interfacial surface. In vivo experiments demonstrate that polyethylene glycol inhibits more than 90% of the myotoxic effects without exhibiting secondary toxic effects. The crystal structure of bothropstoxin-I complexed with polyethylene glycol reveals that this inhibition is due to steric hindrance of the access to the PLA(2)-active site-like region. These two inhibitory pathways indicate the roles of the overall surface charge and free accessibility to the PLA2-active site-like region in the functioning of Lys49 phospholipases A(2) homologues. Molecular dynamics simulations, small angle X-ray scattering and structural analysis indicate that the oligomeric states both in solution and in the crystalline states of Lys49 phospholipases A2 are principally mediated by hydrophobic contacts formed between the interfacial surfaces. These results provide the framework for the potential application of both clinically approved drugs for the treatment of Viperidae snakebites. (c) 2006 Elsevier Ltd. All rights reserved.

Efficiency of extrinsic and intrinsic charge-carrier photogeneration processes obtained from the steady-state photocurrent action spectra of poly(p-phenylene vinylene) derivatives

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Speciation of butyltin derivatives in surface sediments of three southern Brazilian harbors

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

In vitro Trypanocidal Activity of Phenolic Derivatives from Peperomia obtusifolia

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