Navegando por Assunto "Produto natural"

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Acesso aberto (Open Access)
Avaliação da influência da natureza da matriz sólida sobre a extração supercrítica de óleos vegetais
(Universidade Federal do Pará, 2013-05-10) COSTA, João Fernando Alves; FRANÇA, Luiz Ferreira de; http://lattes.cnpq.br/6545345391702172
The extraction of substances from solid substrates both low and high pressures involves at least two phases, a solid and another fluid. The content of the solute in each phase is expressed in terms of the volume of phase and / or volume of solvent. Then, by modeling the interfacial mass transfer it requires a partition coefficient. In general, the simplest way to address this problem is to model the phases separately. The mechanism predominant mass transfer can vary from system to system. For some substrates higher resistance may be in the solid phase and for others it is in the fluid phase. As the interface concentrations for each phase are represented by different variable, phases have to be modeled separately. However, depending on the system, there may be a transfer mechanism predominated over the other, and many effects can be discarded for simplification of the model. The utilization of simpler mathematical models requires a combination of variables for definition of parameters that can represent the phenomenon. In this work the extraction curves were fitted to a model which describes the interfacial mass transfer like a first order kinetics, since the constant of the extraction rate is the unique adjustment parameter. It has been proposed that the adjustment parameter depends on the solubility of solute in the supercritical solvent and on the solid substratum characteristics. To avail that, extraction experiments with babaçu, powder açaí and pupunha pulp using super-critic carbon dioxide at 20, 25 and 30 MPa and temperature of 50°C have been carried out. The results showed that the experimental data fit well to a model with a constant characteristic of each material, with values 4.1983 x 10-5 m/kg∙s to babaçu, 4.2258 x 10-5 m/kg∙s to pupunha pulp, to 10-5 m/kg∙s to powder açaí.
Acesso aberto (Open Access)
Dados espectroscópicos de diterpenos labdânicos: uma análise teórica via RMN e DFT
(2015-06) SOUZA, Fabrine Silva de; SILVA, Silvana de Oliveira; FARIA, Lênio José Guerreiro de; ALVES, Claudio Nahum; MÜLLER, Adolfo Henrique; GUILHON, Giselle Maria Skelding Pinheiro; BRASIL, Davi do Socorro Barros
Labdane diterpenes exhibit important bioactivities such as cardiovascular effects in rats as well as effects in the treatment of autoimmune diseases and Alzheimer syndrome. Recently, the labdane diterpenes ent-13-epi-manoil oxide, ribenone and ribenol were isolated from Croton palanostigma. The computational method DFT/B3LYP/cc-pVDZ was used to optimize the structures of these diterpenes and to calculate infrared data. Chemical shifts (δH and δC) of the minimum energy structures (local minimum) were calculated and compared with the experimental data. Comparison of the NMR data by simple linear regression (SLR) showed satisfactory statistical results with a correlation coefficient (R2) and predictive ability (Q2) of over 98%. The predicted NMR data were used to confirm the δH values that have not been published.
Acesso aberto (Open Access)
Extração de oleoresina de Cúrcuma (Curcuma longa l) com CO2 supercrítico
(1997-12) CHASSAGNEZ MÉNDEZ, Angel Luis; CORRÊA, Nádia Cristina Fernandes; MEIRELES, Maria Angela de Almeida
Turmeric (Curcuma longa L) is one of the most used source of natural color in the food industry. Curcuminoids can be obtained from the roots of this plant. These pigments impact a yellow color and they might be able to substitute synthetic dyes. Turmeric oleoresin extraction experiments have been carried out with supercritical CO2 to investigate the influences of the pretreatment of the rhizomes on oleoresin. The extractions were conducted at the Department of Chemical Engineering of the Federal University of Pará (Universidade Federal do Pará). Turmeric was dried at 70ºC and 105ºC. Extractions have been carried out at pressures of 200, 250 and 300 bar and a temperature of 45ºC. Results shown the total yield and the content of curcumin present in the oleoresin. Amount of oleoresin extracted from the material dried at 70ºC was larger while most of the curcuminoids remained in the solid material.
Acesso aberto (Open Access)
A mass transfer model applied to the supercritical extraction with CO2 of curcumins from turmeric rhizomes (Curcuma longa L)
(2000-09) CHASSAGNEZ MÉNDEZ, Angel Luis; CORRÊA, Nádia Cristina Fernandes; FRANÇA, Luiz Ferreira de; MACHADO, Nélio Teixeira de; ARAÚJO, Marilena Emmi
Increasing restrictions on the use of artificial pigments in the food industry, imposed by the international market, have increased the importance of raw materials containing natural pigments. Of those natural substances with potential applications turmeric rhizomes (Curcuma longa L), are one of the most important natural sources of yellow coloring. Three different pigments (curcumin, desmetoxycurcumin, and bis-desmetoxycurcumin) constitute the curcuminoids. These pigments are largely used in the food industry as substitutes for synthetic dyes like tartrazin. Extraction of curcuminoids from tumeric rhizomes with supercritical CO2 can be applied as an alternative method to obtain curcuminoids, as natural pigments are in general unstable, and hence degrade when submitted to extraction with organic solvents at high temperatures. Extraction experiments were carried out in a supercritical extraction pilot plant at pressures between 25 and 30 MPa and a temperature of 318 K. The influence of drying pretreatment on extraction yield was evaluated by analyzing the mass transfer kinetics and the content of curcuminoids in the extracts during the course of extraction. The chemical identification of curcuminoids in both the extract and the residual solid was performed by spectrophotometry. Mass transfer within the solid matrix was described by a linear first-order desorption model, while that in the gas phase was described by a convective mass transfer model. Experimental results showed that the concentration profile for curcuminoids during the supercritical extraction process was higher when the turmeric rhizomes were submitted to a drying pretreatment at 343 K.
Acesso aberto (Open Access)
Plant-derived antimalarial agents: new leads and efficient phythomedicines. Part I. Alkaloids
(2009-12) OLIVEIRA, Alaíde Braga de; DOLABELA, Maria Fâni; BRAGA, Fernão Castro; JÁCOME, Rose Lisieux Ribeiro Paiva; VAROTTI, Fernando de Pilla; PÓVOA, Marinete Marins
Malaria remains one of the most serious world health problem and the major cause of mortality and morbidity in the endemic regions. Brazil is among the 30 high-burden countries and most of the cases occur in the Legal Amazonian Region. New chemotherapeutical agents are needed for the treatment of malaria. Many plant species are used in traditional medicines of malarious countries and a relatively few number of these have been investigated for evaluation of their antimalarial effect. Still lower is the number of those that have had the active natural compounds isolated and the toxicity determined. This area is, then, of great research interest. discovery project of antimalarial natural products from plants traditionally used to treat malaria must include in vitro and in vivo assays as well as bioguided isolation of active compounds. The final products would be antimalarial chemical entities, potential new drugs or templates for new drugs development, and/or standardized antimalarial extracts which are required for pre-clinical and clinical studies when the aim is the development of effective and safe phythomedicines. This review discusses these two approaches, presents briefly the screening methodologies for evaluation of antimalarial activity and focuses the activity of alkaloids belonging to different structural classes as well as its importance as new antimalarial drugs or leads and chemical markers for phytomedicines.