RESUMO
Varios metodos analiticos foram desenvolvidos com a finalidade de obter procedimentos simples, rapidos e economicos para a determinacao de pro-vitamina A em alimentos. Neste trabalho tres desses metodos foram avaliados: os de COST91,IVACG e RODRIGUEZ-AMAYA et alii simplificado. Os alimentos escolhidos foram couve, cenoura, mamao e tomate, devido as suas caracteristicas distintas quanto a composicao de pro-vitamina A. As principais deficiencias apresentadas pelo metodo recomendado por COST91 foram a extracao incompleta e a saponificacao drastica. Outra grande falha do metodo foi a nao separacao entre alfa e beta-caroteno, e a nao consideracao da alfa e beta-criptoxantina e do beta-caroteno. Para o metodo apresentado pelo IVACG, a extracao foi insuficiente apenas para couve. Esse metodo demonstrou ser mais versatil que COST92, pois permitiu a separacao das diferentes pro-vitaminas. Dos procedimentos de saponificacao sugeridos, a saponificacao a frio confirmou ser a tecnica mais aconselhavel. O metodo de RODRIGUEZ-AMAYA et alii simplificado mostrou ser o mais indicado, principalmente pela sua simplicidade e exatidao
Assuntos
Carotenoides/análise , Frutas/análise , Métodos , Plantas/análise , Vitamina A/análise , Análise de Alimentos , Plantas Comestíveis/análiseRESUMO
Subacute intraperitoneal administration of the lipid portion of the unripe ackee arillus, referred to as "ackee oil", resulted in marked neutropenia (p<0.001) and increase in platelets (p<0.01) without anaemia, in rats. Blood urea, sodium amd aspartate aminotransferase levels were significantly decreased but glucose and bilirubin levels were similar to those of controls. The lungs showed areas of petechial haemorrhaghes and a dose-related perivascular and peribronchial mononuclear cell infiltration. The pulmonary toxicity may be interpreted as a hypersensitive reaction to ackee oil. Further research is in progress on the neutropenic effects of ackee oil.
Assuntos
Plantas Comestíveis/análise , Neutropenia/induzido quimicamenteRESUMO
The complexity of plant foods high in dietary fiber poses new challenges to clinical investigators and leads to many study-design dilemmas. There are basic differences in studying purified polymers, highly concentrated but not purified fibers, and diets high in high-fiber whole foods. The fibrils of the plant cell wall are most likely altered when prepared as a pure chemical entity, and when fiber concentrates (eg, wheat bran) are used, the method of preparation may alter the composition of the final product. Whole-plant, high-fiber foods are complex storehouses of a diversity of polymers, including resistant starch, and of bioactive compounds. Furthermore, the addition of a reasonable amount of high-fiber food to the diet not only adds dietary fiber but many digestible, caloric macronutrients that alter the entire diet composition. These problems and dilemmas are reviewed.
Assuntos
Fibras na Dieta/química , Análise de Alimentos , Plantas Comestíveis/análise , Parede Celular/química , Fibras na Dieta/administração & dosagem , Ingestão de Alimentos , Humanos , Polímeros , Sementes/análise , Amido/administração & dosagem , Amido/metabolismoRESUMO
The ethylenebisdithiocarbamate (EBDC) fungicide, nabam, was determined in several crop matrixes using liquid chromatography with postcolumn reaction detection. After separation by micellar liquid chromatography, nabam (EBDC sodium salt) was acid hydrolyzed to ethylenediamine and fluorigenically labeled with o-phthalaldehyde-mercaptoethanol (OPA-MERC). Standard curves were linear from the detection limit of ca 1 ng to 1000 ng. Nabam was recovered in high yield (89 plus or minus 7.7%) over a range of concentrations (0.1 to 20 ppm) from fortified samples of papaya, lettuce, cucumber, spinach, and applesauce using a simple extraction method. Efforts to convert the more popular EBDC fungicides, maneb and mancozeb, to nabam are discussed.
Assuntos
Etilenobis (ditiocarbamatos)/análise , Fungicidas Industriais/análise , Plantas Comestíveis/análise , Cetilpiridínio , Cromatografia Líquida/métodos , Ácido Edético , Frutas/análise , Hidrólise , Mercaptoetanol , Verduras/análise , o-FtalaldeídoRESUMO
An analytical procedure previously developed for the trace determination of nitrosamides was applied to a screening of nitrosated foodstuffs for nitrosoureas. Different types of foodstuffs were nitrosated both under chemical conditions using a high nitrite concentration, and under simulated gastric conditions. Methylating activity corresponding to N-nitroso-N-methylurea (MNU) was detected in most samples. Under chemical conditions, the yields spanned several orders of magnitude with processed fish and meat products being at the top, and plant products at the bottom of the scale. After nitrosation under simulated gastric conditions, the range of MNU activity was significantly smaller. No correlation exists between the yields determined under chemical and simulated gastric conditions.
Assuntos
Análise de Alimentos , Compostos Nitrosos/análise , Animais , Cromatografia Gasosa , Produtos Pesqueiros/análise , Suco Gástrico/metabolismo , Concentração de Íons de Hidrogênio , Produtos da Carne/análise , Metilnitrosoureia/análise , Nitrosação , Compostos de Nitrosoureia/análise , Plantas Comestíveis/análiseRESUMO
Rubusoside (the beta-D-glucosyl ester of 13-O-beta-D-glucosyl-steviol), which is the major sweet principle of leaves of Rubus suavissimus S. Lee, was subjected to 1,4-alpha-transglucosylation by the cyclodextringlucanotransferase-starch system (the CGTase system). The tri- and tetra-glucosylated products were isolated together with the mono- and di-glucosylated products, which had already been isolated. A prominent increase in intensity of the sweetness was observed for the compounds which were di- and tri-glucosylated at the 13-O-glucosyl moiety. This result further substantiated the structure-sweetness relationship for 1,4-alpha-glucosylated compounds of steviol-glycosides reported previously. For protection of the 19-COO-glucosyl moiety against glucosylation by the CGTase system, the 4-hydroxyl group of the 19-COO-glucosyl moiety was beta-galactosylated by the beta-galactosidase-lactose system. This galactosylated compound was subjected to a regio-selective glucosylation of the 13-O-glucosyl moiety by the CGTase system, which was followed by enzymic elimination of the galactosyl group to furnish an exclusive preparation of the improved sweeteners just mentioned.
Assuntos
Diterpenos do Tipo Caurano , Diterpenos/química , Glucosídeos/química , Sequência de Carboidratos , Diterpenos/isolamento & purificação , Glucosídeos/isolamento & purificação , Glicosilação , Dados de Sequência Molecular , Estrutura Molecular , Plantas Comestíveis/análise , Edulcorantes/química , Edulcorantes/isolamento & purificaçãoAssuntos
Carcinógenos , Plantas Comestíveis , Humanos , Plantas Comestíveis/análise , Fatores de Risco , América do SulRESUMO
With the aid of a new chiral derivatizing reagent and a sensitive and specific assay using capillary gas chromatography/negative ion chemical ionization mass spectrometry, the proportions of R and S enantiomers of 1-methyl-1,2,3,4-tetrahydroisoquinoline (1MeTIQ) in mammalian tissues and foods were studied. R- and S-1MeTIQ enantiomers derivatized with a chiral derivatizing reagent, perfluoro-2-propoxypropionylchloride, were clearly separated. The ratio of enantiomers was R/S = 0.24, 0.55 and 0.60 in wine, cocoa and mouse brain. S-1MeTIQ predominated in all samples. This result suggested that 1MeTIQ could be formed at least partially through an enzymatic mechanism.
Assuntos
Química Encefálica , Cacau/análise , Isoquinolinas/análise , Plantas Comestíveis/análise , Tetra-Hidroisoquinolinas , Vinho/análise , Animais , Cromatografia Gasosa , Isoquinolinas/síntese química , Masculino , Espectrometria de Massas , Camundongos , Camundongos Endogâmicos C57BL , Sensibilidade e Especificidade , EstereoisomerismoRESUMO
We conducted an investigation of the levels of the neurotoxin 2-amino-3-(methylamino)-propanoic acid (BMAA) in cycad flour. Analysis of 30 flour samples processed from the endosperm of Cycas circinalis seeds collected on Guam indicated that more than 87% of the total BMAA content was removed during processing. Furthermore, in 1/2 the samples almost all (greater than 99%) of the total BMAA was removed. We found no significant regional differences in the BMAA content of flour prepared from cycad seeds collected from several villages on Guam. Testing of different samples prepared by the same Chamorro woman over 2 years suggests that the washing procedure probably varies in thoroughness from preparation to preparation but is routinely efficient in removing at least 85% of the total BMAA from all batches. Analysis of a flour sample that had undergone only 24 hours of soaking indicated that this single wash removed 90% of the total BMAA. We conclude that processed cycad flour as prepared by the Chamorros of Guam and Rota contains extremely low levels of BMAA, which are in the order of only 0.005% by weight (mean values for all samples). Thus, even when cycad flour is a dietary staple and eaten regularly, it seems unlikely that these low levels could cause the delayed and widespread neurofibrillary degeneration of nerve cells observed in amyotrophic lateral sclerosis and the parkinsonism-dementia complex of Guam (ALS-PD).
Assuntos
Diamino Aminoácidos/análise , Esclerose Lateral Amiotrófica/induzido quimicamente , Farinha/análise , Neurotoxinas/análise , Doença de Parkinson Secundária/induzido quimicamente , Diamino Aminoácidos/efeitos adversos , Toxinas de Cianobactérias , Guam , Humanos , Plantas Comestíveis/análise , Sementes , Estatística como AssuntoRESUMO
Based upon the US National Toxicology Program (NTP) rodent carcinogenicity data base, CASE, an artificial intelligence structure-activity evaluation method, predicts that a large proportion of natural pesticides present in edible plants are rodent carcinogens.
Assuntos
Carcinógenos Ambientais/toxicidade , Praguicidas/toxicidade , Plantas Comestíveis/análise , Animais , Camundongos , Neoplasias Experimentais/induzido quimicamente , Controle Biológico de Vetores , Ratos , Relação Estrutura-AtividadeRESUMO
An attempt was made to estimate the daily intake of 137Cs by moose during different months and seasons, and to compare this result with the 137Cs activity concentration in moose muscles. Plants representative of moose diet in central Sweden showed a high 137Cs activity concentration compared with plants from agricultural systems, and there appears to be very slow reduction of 137Cs activity concentration in these forest plants. It seems that the daily intake of 137Cs was low during the summer, but it exhibited a peak in the autumn, which corresponds to the 137Cs activity concentration in moose muscles and also coincides with the hunting season.
Assuntos
Radioisótopos de Césio/análise , Cervos/metabolismo , Contaminação Radioativa de Alimentos/análise , Plantas Comestíveis/análise , Animais , Músculos/análise , Estações do Ano , SuéciaRESUMO
A continuing study of chemopreventive agents has focused on three categories of naturally-occurring compounds that inhibit carcinogen activation and are effective in preventing carcinogen-induced neoplasia when administered at short time intervals prior to carcinogen challenge. The three are: aromatic isothiocyanates found in cruciferous vegetables, monoterpenes from citrus fruits and caraway seed oils, and organosulfur compounds occurring in Allium species. The short time-interval effects could be significant in terms of their impact on responses of humans to carcinogen exposures. The capacity of sodium cyanate, cruciferous vegetables, orange oil, benzyl isothiocyanate, and D-limonene to act as both blocking and suppressing agents has been discussed. Two possible mechanisms for this multiphase activity were presented. The first is that these inhibitory substances activate a complex integrated defense mechanism against toxic compounds which entails both blocking and suppressing components. The blocking component is the initial line of defense, and the suppressing component constitutes a "fail-safe" backup to assure that if any of the toxic material attacks cellular constituents, its effects will be nullified. The second possible mechanism considered is that the inhibitors, because of high reactivity, have multiple biological effects that are separate and not part of a single, coordinated response. Inhibitors that have both blocking and suppressing effects could be particularly useful as chemopreventive agents.
Assuntos
Neoplasias/prevenção & controle , Extratos Vegetais/farmacologia , Animais , Biotransformação/efeitos dos fármacos , Carcinógenos/farmacocinética , Depressão Química , Feminino , Inativação Metabólica , Camundongos , Neoplasias Experimentais/prevenção & controle , Plantas Comestíveis/análise , RatosAssuntos
Mutação , Extratos Vegetais/farmacologia , Animais , Antracenos , Fenômenos Químicos , Química , Cumarínicos/farmacologia , Flavonoides/farmacologia , Testes de Mutagenicidade , Fenóis/farmacologia , Plantas Comestíveis/análise , Ratos , Salmonella typhimurium/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
In the present study the selenium and chromium content of different plant foods such as fruits, greens, flowers, vegetables, dried fruits, spices, condiments, cereals and pulses were analysed. The selenium values for cereals indehiscent vegetables, root vegetables, stem vegetables, pulses, fleshy vegetables, greens, fleshy fruits, condiment seeds, spices and dried fruits ranged between 24.2-32.16, 2.4-18.9, 2.8-21.5, 3.0-32, 48.7-92.5, 1.25-9.5, 3.0-8.2, 2.0-9.4, 6.2-66.2, 6.2-17.5 and 3.5-16.8 micrograms/100 g respectively. The chromium values for the same ranged between 48.2-52.6, 31.0-45, 21.2-25.7, 23.7-62.8, 15.0-43.5, 20.4-65, 14.2-42.1, 14.25-46.7, 58.4-150 and 96-168 micrograms/100 g respectively. Thus dried fruits have the highest chromium content and pulses the highest selenium content.
Assuntos
Cromo/análise , Grão Comestível/análise , Frutas/análise , Plantas Comestíveis/análise , Selênio/análise , Cromo/isolamento & purificação , Análise de Alimentos , Técnicas In Vitro , Selênio/isolamento & purificação , Espectrofotometria AtômicaRESUMO
In this review, some common food plants and their toxic or otherwise bioactive components and mycotoxin contaminants have been considered. Crucifers contain naturally occurring components that are goitrogenic, resulting from the combined action of allyl isothiocyanate, goitrin, and thiocyanate. Although crucifers may provide some protection from cancer when taken prior to a carcinogen, when taken after a carcinogen they act as promoters of carcinogenesis. The acid-condensed mixture of indole-3-carbinol (a component of crucifers) binds to the TCDD receptor and causes responses similar to those of TCDD. Herbs contain many biologically active components, with more than 20% of the commercially prepared human drugs coming from these plants. Onion and garlic juices can help to prevent the rise of serum cholesterol. Most herbs used in treatments may have many natural constituents that act oppositely from their intended use. Some herbs like Bishop's week seed contain carcinogens, and many contain pyrrolizidine alkaloids that can cause cirrhosis of the liver. The general phytoalexin response in plants (including potatoes, tomatoes, peppers, eggplant, celery, and sweet potatoes) induced by external stimuli can increase the concentrations of toxic chemical constituents in those plants. In potatoes, two major indigenous compounds are alpha-solanine and alpha-chaconine, which are human plasma cholinesterase inhibitors and teratogens in animals. Because of its toxicity, the potato variety Lenape was withdrawn from the market. Celery, parsley, and parsnips contain the linear furanocoumarin phytoalexins psoralen, bergapten, and xanthotoxin that can cause photosensitization and also are photomutagenic and photocarcinogenic. Celery field workers and handlers continually have photosensitization problems as a result of these indigenous celery furanocoumarins. A new celery cultivar (a result of plant breeding to produce a more pest-resistant variety) was responsible for significant incidences of phytophotodermatitis of grocery employees. Since there is no regulatory agency or body designated to oversee potential toxicological issues associated with naturally occurring toxicants, photodermatitis continues to occur from celery exposure. Sweet potatoes contain phytoalexins that can cause lung edema and are hepatotoxic to mice. At least one of these, 4-ipomeanol, can cause extensive lung clara cell necrosis and can increase the severity of pneumonia in mice. Some phytoalexins in sweet potatoes are hepatotoxic and nephrotoxic to mice. The common mushroom Agaricus bisporus contains benzyl alcohol as its most abundant volatile, and A. bisporus and Gyromitra esculenta both contain hydrazine analogues. Mycotoxins are found in corn, cottonseed, fruits, grains, grain sorghums, and nuts (especially peanuts); therefore, they also occur in apple juice, bread, peanut butter, and other products made from contaminated starting materials.(ABSTRACT TRUNCATED AT 400 WORDS)