Showing papers in "Química Nova in 2006"
TL;DR: The mechanism of action of some reactive oxygen species and reactive nitrogen species in the oxidative stress of the human body, and their consequences on damage to DNA, RNA, proteins and lipids are described.
Abstract: This work describes the mechanism of action of some reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the oxidative stress of the human body, and their consequences on damage to DNA, RNA, proteins and lipids. It also illustrates the defense system of our organism against these ROS and RNS species. The action of nonenzymatic protection systems is reported, with emphasis on micromolecules like Q10 coenzyme, vitamin C, a-tocopherol, carotenoids and flavonoids. The importance of flavonoids is also emphasized, and their body protection mechanism is detailed.
491 citations
TL;DR: In this article, a bibliographic review of research carried out in order to evaluate the antioxidant activity of natural or synthetic substances used in the conservation of food lipid is presented, highlighting the following substances: butylated hydroxyanisole (BHA), BHT, tertiary butylhydroquinone (TBHQ), propyl gallate (PG), tocopherols, phenolic acids and isolated compounds from rosemary and oregano.
Abstract: Lipid oxidation is certainly one of the most important alterations that affect both oils or fats and foods that contain them. It is responsible for the development of unpleasant taste and smell in foods, making them unsuitable for consuming. The use of antioxidants permits a longer useful life of these products. This work presents a bibliographic review of research carried out in order to evaluate the antioxidant activity of natural or synthetic substances used in the conservation of food lipid. Among such substances, the following antioxidants are highlighted: butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tertiary butylhydroquinone (TBHQ), propyl gallate (PG), tocopherols, phenolic acids and isolated compounds from rosemary and oregano.
246 citations
TL;DR: The aim of this tutorial is to introduce an alternative to sophisticated commercial programs that normally are too complex in data input and output by describing a simple way to carry out experimental design calculations applying an spreadsheets.
Abstract: This work describes, through examples, a simple way to carry out experimental design calculations applying an spreadsheets. The aim of this tutorial is to introduce an alternative to sophisticated commercial programs that normally are too complex in data input and output. An overview of the principal methods is also briefly presented. The spreadsheets are suitable to handle different types of computations such as screening procedures applying factorial design and the optimization procedure based on response surface methodology. Furthermore, the spreadsheets are sufficiently versatile to be adapted to specific experimental designs.
226 citations
TL;DR: Chinese traditional medicine is one of the most important examples of how natural products can be efficient in the treatment of diseases, and it points to the importance of scientific research on natural products, concerning the discovery of new active chemical entities.
Abstract: Instituto de Quimica Universidade Estadual Paulista Julio de Mesquita Filho, CP 355, 14801-970 Araraquara - SP
186 citations
TL;DR: A great deal of research has focused on developing biodegradable plastics and its application because it is an important way for minimizing the effect of the large volume of plastic waste discarded in the world as mentioned in this paper.
Abstract: The large use of plastics has generated a waste deposit problem. Today plastic wastes represent 20% in volume of the total waste in the municipal landfills. To solve the disposal problem of plastics methods have been employed such as incineration, recycling, landfill disposal, biodegradation and the use of biodegradable polymers. Incineration of plastic wastes provokes pollution due to the production of poisonous gases. Recycling is important to reduce final costs of plastic materials, but is not enough in face of the amount of discarded plastic. In landfills plastic wastes remain undegraded for a long time, causing space and pollution problems. Biodegradation is a feasible method to treat some plastics, but intensive research is necessary to find conditions for the action of microorganisms. All of these methods are important and the practical application of each one depends on the type and amount of the plastic wastes and the environmental conditions. Therefore, a great deal of research has focused on developing biodegradable plastics and its application because it is an important way for minimizing the effect of the large volume of plastic waste discarded in the world.
113 citations
TL;DR: P. aduncum showed the richest essential oil composition, including linalool, and P. tuberculatum showed the highest antifungal activity with the MIC of 10 µg as determined against Cladosporium cladosporioides and C. sphaerospermum, respectively.
Abstract: The composition of essential oils from leaves, stems and fruits of Piper aduncum, P. arboreum and P. tuberculatum was examined by means of GC-MS and antifungal assay. There was a predominance of monoterpenes in P. aduncum and P. tuberculatum and of sesquiterpenes in P. arboreum. P. aduncum showed the richest essential oil composition, including linalool. The essential oils from fruits of P. aduncum and P. tuberculatum showed the highest antifungal activity with the MIC of 10 µg as determined against Cladosporium cladosporioides and C. sphaerospermum, respectively. This is the first report of the composition of essential oils from P. tuberculatum.
113 citations
TL;DR: In this paper, three Croton species, namely C. zenhtneri, C. nepetaefolius and C. argyrophylloides, were collected at two different times, 6:00 and 13:00 h, their essential oils were extracted by steam distillation and analyzed by gas Chromatography / Mass Spectrometry.
Abstract: Three Croton species, C. zenhtneri, C. nepetaefolius and C. argyrophylloides, were collected at two different times, 6:00 and 13:00 h, their essential oils were extracted by steam distillation and analyzed by gas Chromatography / Mass Spectrometry. The percentage yield of oil constituents changes along the day. The oils were submitted to the antioxidant test thiobarbituric acid reactive species, using BHT and a-tocoferol as the reference compounds. All oils exhibited good antioxidant activities. In general, C. zenhtneri and C. argyrophylloides essential oils showed higher antioxidant activity than C. nepetaefolius.
96 citations
TL;DR: In this article, the authors describe phenol adsorption on commercial active carbon (CAF) under alkaline conditions in the concentration range of 0.01 to 2.08mmol L-1.
Abstract: The present study describes phenol adsorption on commercial active carbon (CAF) under alkaline conditions in the concentration range of 0.01 to 2.08 mmol L-1. Surface characterization has been performed by means of surface area measurements, IR spectroscopy and Boehm titration. The effect of temperature on the adsorption equilibrium isotherm was investigated at 23, 30, 40, 50 and 60 °C. The results showed that adsorption capacity decreased with increasing temperature. The adsorption kinetics and the role of surface characteristics on the adsorption of phenol also discussed.
87 citations
TL;DR: This review describes some aspects of the family Anacardiaceae dealing with the presence and distribution of secondary metabolites in the main genera and their biological activities with special emphasis on phenolic lipids, flavonoids and triterpenes.
Abstract: This review describes some aspects of the family Anacardiaceae dealing with the presence and distribution of secondary metabolites in the main genera of this family and their biological activities. It reports the occurrence of different natural compounds present in their species with special emphasis on phenolic lipids, flavonoids and triterpenes that are typical metabolites of this family.
80 citations
TL;DR: The main properties of vancomycin and related glycopeptide antibiotics are discussed as a background to understanding the design of new chemotherapeutic agents.
Abstract: This article provides an overview on the recent achievements to combat Gram-positive bacteria and the mechanisms related to antimicrobial activity and bacterial resistance. Selected synthetic methodologies to access structurally diverse bioactive compounds are presented in order to emphasize the most important substances currently developed to overcome multiresistant strains. The main properties of vancomycin and related glycopeptide antibiotics are also discussed as a background to understanding the design of new chemotherapeutic agents.
80 citations
TL;DR: This review emphasizes pharmaceutical applications of chitosan and its derivatives, and presents recent advances, and some therapeutical applications of these polymers are also discussed.
Abstract: Chitin and chitosan are copolymers build from N-acetyl-D-glucosamine and D-glucosamine. The former is widely found in nature and yields the latter on deacetylation. The copolymers are being used for several purposes. Since 1977, when the First International Conference on Chitin and Chitosan was held in Boston, USA, the interest on chitin and chitosan has remarkably increased. This review emphasizes pharmaceutical applications of chitosan and its derivatives, and presents recent advances. Some therapeutical applications of these polymers are also discussed.
TL;DR: The well-known sources of vegetal lipases extracted from the latex are described and some of their industrial applications are presented.
Abstract: Biocatalysts have innumerous advantages with respect to classical chemical processes, such as high specificity. Lipases (EC 3.1.1.3) are biocatalysts with large application in synthesis and hydrolysis reactions of triacylglycerols. The search for new sources of lipases has been intensified in the last years due to the high cost of microbial and animal lipases, wich restricts their use on an industrial scale. Lipases obtained from the latex of Carica papaya, Carica pentagona, Euphorbia characias, E. wulfenii, known for their proteolytic properties, are a good alternative source. In this review, we describe the well-known sources of vegetal lipases extracted from the latex and present some of their industrial applications.
TL;DR: In this article, the influence of sugar cane plantations on streams in the central region of the State of Sao Paulo, studying 16 organochlorinated compounds and 7 metals (Cu, Fe, Cd, Zn, Mn, Cr and Ni) found in the sediments of 11 streams.
Abstract: Sugar cane cultivation in the State of Sao Paulo has expanded in the last years, with an annual production of 200106 t in an area of 2.5 106 hectares. The use of herbicides, pesticides and fertilizers in sugar cane plantations, together with deforestation of riparian vegetation, have caused impacts on the hydric resources of the adjacent areas. The aim of this work is to evaluate the influence of sugar cane plantations on streams in the central region of the State of Sao Paulo, studying 16 organochlorinated compounds and 7 metals (Cu, Fe, Cd, Zn, Mn, Cr and Ni) found in the sediments of 11 streams. The results show that there is a higher concentration of metals and organochlorinated compounds in streams without riparian vegetation when compared to forested areas.
TL;DR: In this article, the authors present efforts presented by the scientific community in recent years towards the development of numerous green chemical processes and wastewater treatment technologies, as well as the key role played by the well-known advanced oxidation processes.
Abstract: Efforts presented by the scientific community in recent years towards the development of numerous green chemical processes and wastewater treatment technologies are presented and discussed. In the light of these approaches, environmentally friendly technologies, as well as the key role played by the well-known advanced oxidation processes, are discussed, giving special attention to the ones comprising ozone applications. Fundamentals and applied aspects dealing with ozone technology and its application are also presented.
TL;DR: In this article, a method is proposed for the determination of the moisture content of aromatic plants based on co-distillation of the starting material in a modified Clevenger apparatus with four organic solvents (toluene, cyclohexane, dichloromethane and carbon tetrachloride).
Abstract: A method is proposed for the determination of the moisture content of aromatic plants. This method is based on the co-distillation of the starting material in a modified Clevenger apparatus with four organic solvents (toluene, cyclohexane, dichloromethane and carbon tetrachloride). The results were compared with those obtained by oven drying at 105 oC and steam distillation of the essential oil. The efficiencies of the methods were shown to be equivalent. The solvent distillation method was more practical, especially with respect to operating time (2 h).
TL;DR: The Santos-Cubatao Estuarine System contains a rich mangrove ecosystem that is a habitat for tens of thousands of resident and migratory birds, some of them endangered globally.
Abstract: Multi-element analyses of sediment samples from the Santos-Cubatao Estuarine System were carried out to investigate the spatial and seasonal variability of trace-element concentrations. The study area contains a rich mangrove ecosystem that is a habitat for tens of thousands of resident and migratory birds, some of them endangered globally. Enrichments of metals in fine-grained surface sediments are, in decreasing order, Hg, Mn, La, Ca, Sr, Cd, Zn, Pb, Ba, Cu, Cr, Fe, Nb, Y, Ni and Ga, relative to pre-industrial background levels. The maximum enrichment ranged from 49 (Hg) to 3.1 (Ga). Mercury concentrations were greater in the Cubatao river than in other sites, while the other elements showed greater concentrations in the Morrao river. Concentrations of Mn were significantly greater in winter and autumn than in summer and spring. However, other elements (e.g. Cd and Pb) showed the opposite, with greater concentrations in summer and spring. This study suggests that seasonal changes in physical and chemical conditions may affect the degree of sediment enrichment and therefore make the assessment of contamination difficult. Consequently, these processes need to be considered when assessing water quality and the potential contamination of biota.
TL;DR: In this article, concentration of pseudo-total and bioavailable metals were determined in sediment samples of the Betari River, using atomic absorption spectrometry, and the results demonstrated that the sediments are contaminated by Pb, Zn and Cu.
Abstract: The subsoil of the Vale do Ribeira was the focus of mining industries for the exploration of lead, mainly inside the park - PETAR. Despite the fact that the exploration has ended, the environmental effects of those activities are still present, due to great amounts of heavy metals that are leached. Concentrations of pseudo-total and bioavailable metals were determined in sediment samples of the Betari River, using atomic absorption spectrometry. The results demonstrated that the sediments are contaminated by Pb, Zn and Cu. The findings can contribute to an efficient and environmentally and economically adequate management of the park, for the conservation and the protection of the area.
TL;DR: In this article, the potential application of the zeolitic product for decontamination of waters from acid mine drainage was evaluated, and the results showed that a dose of 30 g L-1 of Zeolitic material allowed the water to reach acceptable quality levels after treatment.
Abstract: Zeolitic material was synthesized from coal fly ashes (baghouse filter fly ash and cyclone filter fly ash) by hydrothermal alkaline activation. The potential application of the zeolitic product for decontamination of waters from acid mine drainage was evaluated. The results showed that a dose of 30 g L-1 of zeolitic material allowed the water to reach acceptable quality levels after treatment. Both precipitation and cation-exchange processes accounted for the reduction in the pollutant concentration in the treated waters.
TL;DR: In this paper, leaves of Lippia alba were submitted to six different drying treatments, using air at ambient temperature and heated up to 80 °C, and the essential oil was extracted by steam distillation and analyzed by GC-MS.
Abstract: Leaves of Lippia alba were submitted to six different drying treatments, using air at ambient temperature and heated up to 80 °C. The essential oil was extracted by steam distillation and analyzed by GC-MS. For the dried leaves, the oil content was reduced by 12 to 17% when compared with the fresh plant (0.66%). The major oil component was citral, representing 76% for the fresh plant, and varying from 82 to 84% for the dried material. These results showed that L. alba can be submitted to a drying process of up to 80 oC without degradation and/or loss of the major, [LC1] active component.
TL;DR: In this article, the authors focus on the use of electrodes of micrometer dimensions to acquire chemical information in microdomains in which concentrations may not be spatially homogeneous.
Abstract: Electrochemical sensors have attracted considerable attention in recent years because they provide data about the chemical state of our surroundings and the dynamics of the chemical transformations in the form a spatially resolved image. Particular interest has been directed to measurements in restricted-volume samples as new technologies enable the fabrication of miniaturized versions of sensors with reproducible characteristics. Taking these aspects into consideration, this review focuses on the use of electrodes of micrometer dimensions to acquire chemical information in microdomains in which concentrations may not be spatially homogeneous. This is possible because microelectrodes allow fast-response measurements with micrometer resolution to be performed. On the other hand, the use of microelectrodes as amperometric sensors presents an inherent drawback owing to the insufficient specificity toward the substrate of interest. Hence, some comments on strategies to enhance the selectivity of amperometric sensors are also made. Finally, recent applications of structurally microscopic electrodes as in vivo sensors are shown, as well as a prospect of the future trend in this field.
TL;DR: In this paper, the authors evaluated the changes in the chemical composition of C. arabica and C. canephora produced by decaffeination using dichloromethane.
Abstract: The decaffeinated coffee market has been expanding increasingly in the last years. During decaffeination, aroma precursors and bioactive compounds may be extracted. In the present study we evaluate the changes in the chemical composition of C. arabica and C. canephora produced by decaffeination using dichloromethane. A significant change in the chemical composition of both C. arabica and C. canephora species was observed, with differences between species and degrees of roasting. Major changes were observed in sucrose, protein and trigonelline contents after decaffeination. Changes in the levels of total chlorogenic acids and in their isomers distribution were also observed. Lipids and total carbohydrates were not affected as much. The sensory and biological implications of these changes need to be investigated.
TL;DR: An overview of the chemical, biological and ethnopharmacological data on Cassia is presented and biologically active piperidine alkaloids are an especially important bioactive class of compounds that showed to be restricted to a small group of Cassia species.
Abstract: Species of Cassia are widely distributed in tropical and subtropical regions throughout the world, and have been extensively investigated chemically and pharmacologically.They are known to be a rich source of phenolic derivatives, most of them with important biological and pharmacological properties. Some Asian, African and Indian tribes use these species as a laxative, purgative, antimicrobial, antipyretic, antiviral and anti-inflammatory agent. Among a number of other classes of secondary metabolites, such as anthracene derivatives, antraquinones, steroids and stilbenoids, biologically active piperidine alkaloids are an especially important bioactive class of compounds that showed to be restricted to a small group of Cassia species. In this paper we present an overview of the chemical, biological and ethnopharmacological data on Cassia piblished in the literature.
TL;DR: From the therapeutical aspects presented in this work, the evolution of the Cannabis sativa research and the possible medicinal use of cannabinoid compounds are shown.
Abstract: Several cannabinoid compounds present therapeutic properties, but also have psychotropic effects, limiting their use as medicine. Nowadays, many important discoveries on the compounds extracted from the plant Cannabis sativa (cannabinoids) have contributed to understand the therapeutic properties of these compounds. The main discoveries in the last years on the cannabinoid compounds were: the cannabinoid receptors CB1 and CB2, the endogenous cannabinoids and the possible mechanisms of action involved in the interaction between cannabinoid compounds and the biological receptors. So, from the therapeutical aspects presented in this work, we intended to show the evolution of the Cannabis sativa research and the possible medicinal use of cannabinoid compounds.
TL;DR: The major changes in the essential oil composition were found in 135-day-old plants grown under NPK deficiency and three groups of volatile components that have not been previously described in H suaveolens were identified.
Abstract: This study was performed to establish the correlation between the growth conditions and essential oil composition of Hyptis suaveolens from Alfenas (MG), Brazil. The plants were grown in a greenhouse, four treatments were used and they were harvested at two different periods of time (60 and 135-day-old plants). The essential oil composition was determined by GC-MS analysis. The terpenes spathulenol, globulol, dehydroabietol, a-cadinol and b-phellandrene were the major constituents found in the essential oil. Oxygenated sesquiterpenes represented the main group of constituents in most of the treatments. The major changes in the essential oil composition were found in 135-day-old plants grown under NPK deficiency. We also identified three groups of volatile components that have not been previously described in H suaveolens.
TL;DR: In this article, the authors studied the oxidation of three textile dyes (Remazol black B, Remazol Brilliant Orange 3R and Remazols Golden Yellow RNL) using electrochemical and photoelectrochemical methods.
Abstract: This paper presents the study of the oxidation of three textile dyes (Remazol black B, Remazol Brilliant Orange 3R and Remazol Golden Yellow RNL) using electrochemical and photoelectrochemical methods. In both methods, electrolysis experiments were performed at a current density of 50 mA cm-2 in an aqueous solution of each dye (30 mg L-1), using a photoelectrochemical flow-cell. For all the dyes studied, the photoelectrochemical method was demonstrated to be more efficient than the electrochemical one. Photoelectrochemical oxidation resulted in complete decoloration after 90 min of electrolysis and total organic carbon (TOC) removal reached up to 36%. It was observed that the dyes presenting chromophores at higher wavelengths are removed the quickest, which indicates that photosensitised (photoassisted) oxidation occurs. The level of color was reduced to levels below the standards presented in the literature, which indicates the viability of the photoelectrochemical process as part of the treatment of textile effluents.
Abstract: A comparison between silica by acid leaching of rice husk (RH) and silica obtained from thermal treatment of rice husk ash (RHA) is presented. The best leaching results were obtained using 10% hydrochloric acid followed by washing with water. The alternative method, calcination of RHA at 700 oC for 6 h followed by grinding for 80 min, was more effective. Silica obtained from RH was about 97% amorphous, had a 17.37 µm mean particle size, and a specific surface area of 296 m2/g. On the other hand, for silica obtained from RHA the values were about 95% amorphous material 0.68 µm, and 81 m2/g.
TL;DR: In this article, a water quality index is developed to subsidize management actions in the Atibaia River for upon protection of aquatic organisms, composed of two measurable environmental parameters normaly, ammonia and dissolved oxygen, the latter representing the contribution of organic matter.
Abstract: In this paper a water quality index is developed to subsidize management actions in the Atibaia River for upon protection of aquatic organisms. This index is composed of two measurable environmental parameters normaly, ammonia and dissolved oxygen, the latter representing the contribution of organic matter. Concentrations of these two variables were normalized on a scale from 0 to 100 and translated into statements of quality (excellent, good, regular, bad and very bad). The index was applied to three monitoring points in the Atibaia River and compared to other indices used by the State of Sao Paulo Environmental Agency (CETESB). The results showed that the degradation in this watershed follows the urban population density. The developed index is more restricted than the other ones routinely used to infer water quality.
TL;DR: An overview of the current literature on the chemical processes involved in the ion formation from low molecular weight organic compounds by electrospray ionization mass spectrometry is given in this article.
Abstract: An overview of the current literature on the chemical processes involved in the ion formation from low molecular weight organic compounds by electrospray ionization mass spectrometry is given.
TL;DR: In this article, a brief description of the problem as well as the physical and chemical characteristics of the main compounds, the environmental behavior, methods of determination, ecotoxicological aspects and a discussion about its relevance in terms of ecology and public health are presented.
Abstract: Natural and synthetic estrogens have been detected in rivers, lakes and estuaries in several parts of the world. The primary sources of these compounds are the industrial and household effluents, which are not eliminated by the received treatment. This paper presents a brief description of the problem as well as the physical and chemical characteristics of the main compounds, the environmental behavior, methods of determination, ecotoxicological aspects and a discussion about its relevance in terms of ecology and public health.
TL;DR: In this article, the phytochemical analysis of the trunk bark of Amburana cearensis allowed the isolation and identification of twelve constituents: coumarin, sucrose, two phenol acids (vanillic acid and protocatechuic acid), five flavonoids (afrormosin, isokaempferide, kaempferol, quercetin and 4'-methoxy-fisetin), a phenol glucoside (amburoside A) and a mixture of glucosilated b-sitosterol and stig
Abstract: The phytochemical analysis of the ethanol extract trunk bark of Amburana cearensis allowed the isolation and identification of twelve constituents: coumarin, sucrose, two phenol acids (vanillic acid and protocatechuic acid), five flavonoids (afrormosin, isokaempferide, kaempferol, quercetin and 4'-methoxy-fisetin), a phenol glucoside (amburoside A) and a mixture of glucosilated b-sitosterol and stigmasterol. Their structures were elucidated by spectroscopic methods such as IR, MS, 1H and 13C NMR, including uni and bidimensional techniques, in addition to comparison with literature data.