Pyrodysinoic Acid Derivatives from the Marine Sponge Dysidea robusta

Three new nitrogen-containing terpenes related to pyrodysinoic acid (1) have been isolated from the sponge Dysidea robusta collected in Brazil. Isopyrodysinoic acid (2), 13-hydroxyisopyrodysinoic acid (3), and pyrodysinoic acid B (4) were obtained from the crude extract of D. robusta and identified by analysis of spectroscopic data. Pyrodysinoic acid B (4) is the first furodysin or furodysinin sesquiterpene derivative with a trans junction between the two six-membered rings of the 1,2,3,4,4a,7,8,8a-octahydro-1,1,6-trimethylnaphthalene moiety.

Synthesis, Spectroscopic Studies and X-ray Crystal Structures of New Pyrazoline and Pyrazole Derivatives

The synthesis and characterization of some pyrazoline compounds of 1,3-diketones with hydrazine derivatives, namely, 1-(S-benzyldithiocarbazate)-3-methyl-5-phenyl-5-hydroxypyrazoline (1); 1-(2-thiophenecarboxylic)-3-methyl-5-phenyl-5-hydroxypyrazoline (2); 1-(2-thiophenecarboxylic)-3,5-dimethyl-5-hydroxypyrazoline (3); 1-(S-benzyldithiocarbazato)-3-methyl-5-phenylpyrazole (4); 1-(2-thiophenecarboxylic)-3-methyl-5-phenylpyrazole (5) and 1-(S-benzyldithiocarbazate)-3,5-dimethylpyrazole (6) are reported. Studies by IR, ((1)H, (13)C)-NMR spectroscopies and single crystal X-ray diffraction revealed that compounds (1)(,) (2) and (3) are formed as pyrazoline, whereas (4) and (5) are formed as pyrazole derivatives only under acidic conditions. Compound (1) crystallizes in orthorhombic P2(1)2(1)2(1), a = 6.38960(10) angstrom, b = 12.9176(3) angstrom, c = 21.2552(5) angstrom, (2) crystallizes in monoclinic, P2(1)/n, a = 11.3617(2) angstrom, b = 8.4988(2) angstrom, c = 92.8900(10)angstrom and beta = 92.8900(5)degrees, (3) crystallizes in monoclinic, C2/c, a = 15.9500(5) angstrom, b = 9.3766(3) angstrom, c = 16.6910(5)angstrom and beta = 113.825(2)degrees, (4) crystallizes in monoclinic, P2(1)/c, a = 15.228(4) angstrom, b = 5.5714(13) angstrom, c = 19.956(5)angstrom and beta = 91.575(7)degrees and (6) crystallizes in orthorhombic, P2(1)2(1)2(1), a = 5.3920(2) angstrom, b = 11.2074(5) angstrom, c = 21.885(1)angstrom . The (3) derivative represents the first pyrazoline compound prepared from 2,4-pentanedione and characterized crystallographically.

Structural and Electronic Properties of Dipyridamole and Derivatives

Quantum mechanical calculations at the B3LYP theory level, together with the 6-31G* basis set, were employed to obtain the energy, ionization potential, and polarizabilites for dipyridamole and derivatives, which are compared with their biological activity. Density functional calculations of the spin densities were performed for radical formed by electron abstraction of dipyridamole and derivatives. The unpaired electron remains in dipyridamole is localized on the nitrogen atoms in the substituent positions 1, 3, 5, 7, 11, 12, 13, 14, with participation of the 9 and 10 carbons in the pyrimido-pyrimidine ring. The antioxidant activity is related with ionization potential, polarizability and Log P.

Synthesis, spectroscopic characterization and X-ray structures of five-coordinate diorganotin(IV) complexes containing 5-hydroxypyrazoline derivatives as ligands

Four new diorganotin(IV) complexes have been prepared from R(2)SnCl(2) (R = Me, Ph) with the ligands 5-hydroxy-3-metyl-5-phenyl-1-(S-benzildithiocarbazate)-pyrazoline (H(2)L(1)) and 5-hydroxy-3-methyl-5-phenyl-1-(2-thiophenecarboxylic)-pyrazoline (H(2)L(2)). The complexes were characterized by elemental analysis, IR. (1)H (13)C, (119)Sn NMR and Mossbauer spectroscopes The complexes [Me(2)SnL(1)], [Ph(2)SnL(1)] and [Me(2)SnL(2)] were also studied by single crystal X-ray diffraction and the results showed that the Sn(IV) central atom of the complexes adopts a distorted trigonal bipyramidal (TBP) geometry with the N atom of the ONX-tridentate (X = O and S) ligand and two organic groups occupying equatorial sites. The C-Sn-C angles for [Me(2)Sn(L(1))] and [Ph(2)Sn(L(1))] were calculated using a correlation between (119)Sn Mossbauer and X-ray crystallographic data based on the point-charge model Theoretical calculations were performed with the B3LYP density functional employing 3-21G(*) and DZVP all electron basis sets showing good agreement with experimental findings General and Sn(IV) specific IR harmonic frequency scale factors for both basis sets were obtained from comparison with selected experimental frequencies (C) 2010 Elsevier B V All rights reserved

Antifungal activity of tri- and tetra-thioureido amino derivatives against different Candida species

The in vitro antifungal activity of six thioureido substituted amines (P1-P6) was evaluated against Candida species, including Candida albicans, C. glabrata, C. krusei and C. parapsilosis. These tri- and tetra-thioureido amino derivatives with different methylation levels were synthesised through easy synthetic routes to evaluate their antifungal properties against Candida species. Among all studied derivatives, the tri-(2-thioureido-ethyl)-amine (P1) was the most active compound inhibiting C. albicans and C. glabrata at a concentration of 0.49 mu g ml(-1); P3, the N,N `,N ``,N ```-hexamethyl-derivative, also showed inhibitory activity against C. albicans and C. glabrata, but in higher concentrations (250 mu g ml(-1)). The N,N `,N ``,N ```-tetramethylated amine (P5) only inhibited the growth of C. glabrata, but its corresponding N,N `,N ``,N ```-octamethyl derivative (P6) was also active against C. glabrata (125 mu g ml(-1)) and it was the only compound active against C. parapsilosis. P2 and P4 showed no significant antifungal activity. The structure-activity relationship of the thioureido-substituted derivatives indicates that the molecular branching and the alkylation levels can influence the antifungal activity. This study demonstrated that thioureido derivatives exhibited significant antifungal activity against Candida species and that they can be considered as a very promising bioactive lead compound to develop novel antifungal agents.

Pricing and competition in the Swedish retail market for electricity

Sweden, together with Norway, Finland and Denmark, have created a multi-national electricity market called NordPool. In this market, producers and retailers of electricity can buy and sell electricity, and the retailers then offers this electricity to end consumers such as households and industries. Previous studies have shown that pricing at the NordPool market is functioning quite well, but no other study has to my knowledge studied if pricing in the retail market to consumers in Sweden is well functioning. If the market is well functioning, with competition and low transaction costs when changing electricity retailer, we would expect that a homogeneous good such as electricity would be sold at the approximately same price, and that price changes would be highly correlated, in this market. Thus, the aim of this study is to test whether the price of Vattenfall, the largest energy firm in the Swedish market, is highly correlated to the price of other firms in the Swedish retail market for electricity. Descriptive statistics indicate that the price offered by Vattenfall is quite similar to the price of other firms in the market. In addition, regression analysis show that the correlation between the price of Vattenfall and other firms is as high as 0.98.

Cálculo do subsídio implícito a agricultura, proveniente da política de preços mínimos, utilizando a teoria de "option pricing"

O objetivo desse trabalho é calcular o subsídio implícito aos produtores de arroz agulhinha, feijão preto, milho e soja, proveniente da política de preços mínimos, através da avaliação dos prêmios das opções de venda que correspondem à política de preços mínimos para essas commodities.

Tests of conditional asset pricing models in the brazilian stock market

In this paper, we test a version of the conditional CAPM with respect to a local market portfolio, proxied by the Brazilian stock index during the period 1976-1992. We also test a conditional APT modeI by using the difference between the 3-day rate (Cdb) and the overnight rate as a second factor in addition to the market portfolio in order to capture the large inflation risk present during this period. The conditional CAPM and APT models are estimated by the Generalized Method of Moments (GMM) and tested on a set of size portfolios created from individual securities exchanged on the Brazilian markets. The inclusion of this second factor proves to be important for the appropriate pricing of the portfolios.

The role of no-arbitrage on forecasting: lessons from a parametric term structure model

Parametric term structure models have been successfully applied to innumerous problems in fixed income markets, including pricing, hedging, managing risk, as well as studying monetary policy implications. On their turn, dynamic term structure models, equipped with stronger economic structure, have been mainly adopted to price derivatives and explain empirical stylized facts. In this paper, we combine flavors of those two classes of models to test if no-arbitrage affects forecasting. We construct cross section (allowing arbitrages) and arbitrage-free versions of a parametric polynomial model to analyze how well they predict out-of-sample interest rates. Based on U.S. Treasury yield data, we find that no-arbitrage restrictions significantly improve forecasts. Arbitrage-free versions achieve overall smaller biases and Root Mean Square Errors for most maturities and forecasting horizons. Furthermore, a decomposition of forecasts into forward-rates and holding return premia indicates that the superior performance of no-arbitrage versions is due to a better identification of bond risk premium.

Arbitrage Pricing Theory (APT) e variáveis macroeconômicas: um estudo empírico sobre o mercado acionário brasileiro

Este trabalho utiliza retornos mensais de 10 portfólios de ações negociadas na Bovespa entre 1987 e 1997, a fim de testar a validade empírica do modelo APT. Foram criadas variáveis macroeconômicas como fatores de variância comum aos diversos portfólios. Além destes fatores serem estatisticamente significantes para explicar a relação entre os retornos dos diversos portfólios de uma maneira geral, foram encontradas evidências no sentido de validar o APT.

A stochastic discount factor approach to asset pricing using panel data

Using the Pricing Equation, in a panel-data framework, we construct a novel consistent estimator of the stochastic discount factor (SDF) mimicking portfolio which relies on the fact that its logarithm is the ìcommon featureîin every asset return of the economy. Our estimator is a simple function of asset returns and does not depend on any parametric function representing preferences, making it suitable for testing di§erent preference speciÖcations or investigating intertemporal substitution puzzles.

Simple calvo economies with heterogeneous pricing

A motivação para este trabalho vem dos principais resultados de Carvalho e Schwartzman (2008), onde a heterogeneidade surge a partir de diferentes regras de ajuste de preço entre os setores. Os momentos setoriais da duração da rigidez nominal são su cientes para explicar certos efeitos monetários. Uma vez que concordamos que a heterogeneidade é relevante para o estudo da rigidez de preços, como poderíamos escrever um modelo com o menor número possível de setores, embora com um mínimo de heterogeneidade su ciente para produzir qualquer impacto monetário desejado, ou ainda, qualquer três momentos da duração? Para responder a esta questão, este artigo se restringe a estudar modelos com hazard-constante e considera que o efeito acumulado e a dinâmica de curto-prazo da política monetária são boas formas de se resumir grandes economias heterogêneas. Mostramos que dois setores são su cientes para resumir os efeitos acumulados de choques monetários, e economias com 3 setores são boas aproximações para a dinâmica destes efeitos. Exercícios numéricos para a dinâmica de curto prazo de uma economia com rigidez de informação mostram que aproximar 500 setores usando apenas 3 produz erros inferiores a 3%. Ou seja, se um choque monetário reduz o produto em 5%, a economia aproximada produzirá um impacto entre 4,85% e 5,15%. O mesmo vale para a dinâmica produzida por choques de nível de moeda em uma economia com rigidez de preços. Para choques na taxa de crescimento da moeda, a erro máximo por conta da aproximação é de 2,4%.

Avaliação de métodos numéricos para precificação de derivativos: aplicação ao mercado brasileiro

Os objetivos deste trabalho foram (i) rever métodos numéricos para precificação de derivativos; e (ii) comparar os métodos assumindo que os preços de mercado refletem àqueles obtidos pela fórmula de Black Scholes para precificação de opções do tipo européia. Aplicamos estes métodos para precificar opções de compra da ações Telebrás. Os critérios de acurácia e de custo computacional foram utilizados para comparar os seguintes modelos binomial, Monte Carlo, e diferenças finitas. Os resultados indicam que o modelo binomial possui boa acurácia e custo baixo, seguido pelo Monte Carlo e diferenças finitas. Entretanto, o método Monte Carlo poderia ser usado quando o derivativo depende de mais de dois ativos-objetos. É recomendável usar o método de diferenças finitas quando se obtém uma equação diferencial parcial cuja solução é o valor do derivativo.

Arbitrage pricing theory (APT) : uma aplicação na Bolsa de Valores de São Paulo

O presente trabalho tem como objetivos explicar os retornos do índice da Bolsa de valores de São Paulo, o IBOVESPA, no período após a implantação do Plano Real, iniciando-se por janeiro de 1995 e tínanzando-se em agosto de 1998, através de variáveis macroeconômicas, utilizando-se do ferramental proposto pelo "Arbitrage Pricing Theory", considerando trabalhos realizados no mundo, bem como as especificidades do mercado brasileiro e divulgar a teoria, suas premissas e vantagens à comunidade e ao mercado, a fim de estimular sua utilização, através do uso de variáveis de fácil acesso aos analistas.

Testes de validade do capital asset pricing model no mercado acionário de São Paulo : um estudo indicativo do poder de teste da metodologia de Fama e Macbeth

Utiliza a técnica de simulação para estimar a "eficiência" de se testar o modelo Capital Asset Pricing Model (CAPM) num mercado com características do mercado acionário paulista, marcado por elevado retorno e alta volatilidade.