Tropical biodiversity: has it been a potential source of secondary metabolites useful for medicinal chemistry?

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

Analysis of the secondary compounds produced by Saccharomyces cerevisiae and wild yeast strains during the production of cachaça

O presente trabalho visou estabelecer uma comparação entre composição de cachaças produzidas por Saccharomyces cerevisiae (Sc) e estirpes de leveduras selvagens [Pichia silvicola (Ps), Pichia anomala 1 (Pa1), Pichia anomala 2 (Pa2) e Dekkera bruxelensis (Db)], isoladas em destilarias da região de Jaboticabal-SP. Os componentes secundários da fração denominada coração foram determinados por cromatografia gasosa. Os níveis dos componentes secundários foram influenciados pelo pH dos respectivos vinhos, os quais dependem da estirpe de levedura empregada no processo fermentativo. A Saccharomyces cerevisiae apresentou valores ligeiramente superiores de componentes secundários, enquanto as estirpes selvagens produziram maiores teores de álcoois superiores. As estirpes selvagens de leveduras mostraram-se adequadas para obtenção de uma cachaça de boa qualidade.

Microalterations in the third eyelid gland of dogs with keratoconjunctivits sicca secondary to distemper

Analisaram-se, à microscopia óptica, 28 glândulas da terceira pálpebra de cães, que morreram com cinomose. O diagnóstico de ceratoconjuntivite seca baseou-se nas alterações da superfície ocular e no teste da lágrima de Schirmer. À histologia, visibilizaram-se atrofia tubuloacina, espessamento do tecido conjuntivo e exudação inflamatória de leve a intensa com presença de plasmócitos, de histiócitos e por hipertrofia compensatória de algumas glândulas. O lume das glândulas encontrava-se hipertrofiado contendo células epiteliais descamadas, polimorfonucleares e hemácias, além de muco.

The Cathodic Cleavage of the Nitrobenzoyl Group from Protected Aliphatic Amines in N,N-Dimethylformamide

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

Thermal behavior of copper(II) pseudohalide complexes containing bidentate amines

Pseudohalide complexes of copper(II) with aliphatic bidentate amines, [Cu(N-3)(2)(N,N-diEten)](2) 1, [Cu(NCO)(2)(N,N-diEten)](2) 2, [Cu(NCO)(2)(N,N-diMeen)](2) 3, [Cu(N-3)(NCS)(N,N'-diMeen)](2) 4 and [Cu(N-3)(NCO)(N,N-diMeen)](2) 5 (N,N-diEten=N,N-diethylethylenediamine; N,N-diMeen=N,N- dimethyl-ethylenediamine and N,N'-diMeen = N,N'-dimethylethylenediamine), were prepared, characterized and their thermal behavior was investigated by TG curves. According to thermal analysis and X-ray diffraction patterns all compounds decomposed giving copper(II) oxide as final product. The mechanisms of decomposition were proposed and an order of thermal stability was established.

Total secondary-electron yield of metals measured by a dynamic method

The secondary electron emission of dielectrics usually is measured by the pulse method, in which the dielectric is irradiated with short pulses of electrons. Attempts to use a dynamic method, in which the dielectric is irradiated continuously, have failed because the dielectric becomes charged and this charge interferes with the emission process. The dynamic method can, however, be applied to metals where volume charges are prevented. This article reports dynamic measurements of the total secondary emission yield from stainless steel, platinum, and aluminum and compares them with results from the current pulse method. In order to apply the dynamic method to metals a simple but important change in the setup was introduced: a dielectric slab was placed between the electrode and the metallic sample, which permitted the sample surface potential and therefore the energy of the incident electrons to change continuously. Unlike for dielectrics, the emission curves for metals are identical when obtained by the two methods. However, for a sample with deliberately oxidized surfaces the total secondary emission yield is smaller when measured with the dynamic method as compared with the pulse method, just as happens for dielectrics. (C) 2000 American Institute of Physics. [S0021-8979(00)03413-7].

THE CATHODIC CLEAVAGE OF THE NITROBENZENESULFONYL GROUP FROM ALIPHATIC-AMINES IN N,N-DIMETHYLFORMAMIDE

The reduction of benzenesulfonyl derivatives of n-butylamine and N,N-di-n-butylamine with nitro substituents at the 2, 3 and 4 positions of the phenyl ring in N,N-dimethylformamide is reported. The N,N-di-n-butyl-4- and N-n-butyl-2-nitrobenzenesulfonamides are reduced in two cathodic steps. The first one, at about -0.90 V vs. SCE, a reversible one-electron process, gives a stable anion radical. The second reduction step at -1.70 V vs. SCE leads to cleavage of the S-N bond in good yields (> 70%). It is shown that the reduction of the N-n-butyl-3- and N-n-butyl-4-nitrobenzenesulfonamide is different, with three reduction steps. The first reduction step occurs with the formation of an unstable anion radical, which decomposes via N-H bond cleavage. The reduction of this sulfonamide anion occurs at -1.16 V vs. SCE and the third cathodic step arises at -1.70 V vs. SCE when the remaining radical anion is reduced to its dianion. The S-N bond cleavage is rapid but is always a minor process. The mechanisms of the reduction are discussed.

2-nitro- and 2,4-dinitrobenzenesulfonamides as protecting groups for primary amines

Procedures for the deprotection of the 2-nitro- and 2,4-dinitrobenzenesulfonamides to give the corresponding primary amines were developed. The 2-Nitrobenzenesulfonyl group was effectively removed by HSCH2CH2OH/DBU or PhSH/Cs2CO3 in DMF under mild conditions to give the corresponding primary amines in high to excellent yield. For removal of the 2,4-dinitrobrnzenesulfonyl group, the use of thiol alone (HSCH2CH2OH or PhSH) was quite effective. Selective deprotection of 2,4-dinitrobenzene-sulfonamide in the presence of 2-nitrobznzenesulfonamide has also been achieved.

Secondary phases in Nb-doped BaTiO3 ceramics

In this work, the effect of Nb2O5 addition on the microstructure of BaTiO3 was studied. From XRD diagrams, a diminution in tetragonality parameters with an increase in dopant concentration was observed. In order to determine morphology and composition of secondary phases in niobium-doped barium titanate, EDAX and SEM analyses were carried out. It was found that a concentration of dopant higher than 0.15 mol% leads to fine-grained BaTiO3 without abnormal grain growth. Otherwise, compositions of secondary phases correspond to the titanium-rich region in the BaO-TiO2 phase diagram. Besides, the titanium content in the precipitate increases with the Nb2O5 addition. (C) 2002 Elsevier B.V. Ltd and Techna S.r.l. All rights reserved.

Calcaneal apophysitis: a quantitative radiographic evaluation of the secondary ossification center

Background: Calcaneal apophysitis in children is a self-limited condition that may interfere with walking and physical performance in sports, thus causing concern to the patient and parents. There is still controversy about the significance of the radiographic changes in children with heel pain, since the report of Sever in 1912. One of the reasons is that normal children may display a considerable variation in the radiographic aspects of the secondary ossification center of the calcaneus at different ages. Methods: In this investigation, the developmental aspects of primary and secondary ossification centers of the calcaneus were studied in radiographs obtained from healthy boys and from boys with calcaneal apophysitis. The normal population comprised 392 children and adolescents ranging in age from 6 to 15 years. There were 69 individuals with calcaneal apophysitis ranging in age from 8 to 14 years. Lateral standard radiographs were obtained of both heels, and a copper step wedge was used as a calibration to determine bone density. The following parameters were analyzed on the plain films: time of appearance, fusion and number of fragments of the secondary nucleus, area and bone densitometry of the primary and secondary ossification centers of the calcaneus. Results: In the normal population, the ossification of the secondary nucleus began at 7 years of age, and at 15 years of age, the nucleus was fused in all individuals. In the apophysitis group, the secondary ossification center was present and not fused in all individuals. Both secondary nuclei increased in size with age with no difference between the two groups. Regarding bone density, both the primary and secondary nuclei were less dense in the apophysitis group than their counterparts in the normal population. The most significant difference between the two populations referred to the degree of fragmentation, which was greater in the apophysitis group. Conclusion: Our data showed that the sclerotic aspect of the secondary nucleus of the calcaneus is a normal feature and, therefore, should not be used to establish the diagnosis of Sever's disease. The most consistent difference between the normal and apophysitis group was related to the more fragmented aspect of the secondary nucleus in the latter individuals, which may suggest a mechanical etiology for that condition.

Analysis of secondary phases segregated and precipitated in SnO2-based varistors

Transmission and scanning electron microscopy techniques were used to study the heterogeneities found in the microstructure of (SnO2Co3O4Nb2O5Fe2O3)-Co-.-Nb-.-Fe-. and (SnO2ZnONb2O5FC2O3)-Zn-.-Nb-.-F-. varistors. Second phases encountered both inside the grains and ingrain boundary regions were identified using energy dispersive spectrometry and electron diffraction patterns. Through the electrical characterisation, the presence of iron oxide among the additives was determined to highlight the non-linear properties of the specimens. A discussion on the influence of second phases on the non-linear features of these systems is also addressed. (C) 2004 Elsevier Ltd. All rights reserved.

Analysis of aromatic amines in surface waters receiving wastewater from a textile industry by liquid chromatographic with electrochemical detection

A high performance liquid chromatography ( HPLC) method with electrochemical detection (ED) was developed for the determination of benzidine, 3,3-dimethylbenzidine, o-toluidine and 3,3-dichlorobenzidine in the wastewater of the textile industry. The aromatic amines were eluted on a reversed phase column Shimadzu Shimpack C-18 using acetonitrile + ammonium acetate (1 x 10(-4) mol L-1) at a ratio 46: 54 v/v as mobile phase, pumped at a flow rate of 1.0 mL min(-1). The electrochemical oxidation of the aromatic amines exhibits well-defined peaks at a potential range of +0.45 to +0.78 V on a glassy carbon electrode. Optimum working potentials for amperometric detection were from 0.70 V to +1.0 V vs. Ag/AgCl. Analytical curves for all the aromatic amines studied using the best experimental conditions present linear relationship from 1 x 10(-8) mol L-1 to 1.5 x 10(-5) mol L-1, r = 0.99965, n = 15. Detection limits of 4.5 nM (benzidine), 1.94 nM (o-toluidine), 7.69 nM (3,3-dimethylbenzidine), and 5.15 nM (3,3-dichlorobenzidine) were achieved, respectively. The detection limits were around 10 times lower than that verified for HPLC with ultra violet detection. The applicability of the method was demonstrated by the determination of benzidine in wastewater from the textile industry dealing with an azo dye processing plant.

Chemical evolution in the Asteraceae. The Oxidation-Reduction mechanism and production of secondary metabolites

This work describes the application of partial least squares (PLS) regression to variables that represent the oxidation data of several types of secondary metabolite isolated from the family Asteraceae. The oxidation states were calculated for each carbon atom of the involved compounds after these had been matched with their biogenetic precursor. The states of oxidation variations were named oxidation steps. This methodology represents a new approach to inspect the oxidative changes in taxa. Partial least square (PLS) regression was used to inspect the relationships among terpenoids, cournarins, polyacetylenes, and flavonoids from a data base containing approximately 27,000 botanical entries. The results show an interdependence between the average oxidation states of each class of secondary metabolite at tribe and sub tribe levels.