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1.
Cancer Prev Res (Phila) ; 8(1): 1-8, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25348854

RESUMO

Consuming plants for their presumed health benefits has occurred since early civilizations. Phytochemicals are found in various plants that are frequently included in the human diet and are generally thought to be safe for consumption because they are produced naturally. However, this is not always the case and in fact many natural compounds found in several commonly consumed plants are potential carcinogens or tumor promoters and should be avoided.


Assuntos
Neoplasias/tratamento farmacológico , Compostos Fitoquímicos/toxicidade , Fitoterapia , Extratos Vegetais/química , Plantas/química , Amigdalina/uso terapêutico , Ácidos Aristolóquicos/uso terapêutico , Capsaicina/uso terapêutico , Linhagem Celular Tumoral , Cicasina/uso terapêutico , Dieta , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Indanos/uso terapêutico , Ésteres de Forbol/uso terapêutico , Fitoestrógenos/uso terapêutico , Alcaloides de Pirrolizidina/uso terapêutico , Safrol/uso terapêutico , Sesquiterpenos/uso terapêutico
2.
J Chem Ecol ; 40(8): 860-8, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25172315

RESUMO

An apparent contradiction in the ecology of cycad plants is that their seeds are known to be highly poisonous, and yet they seem well adapted for seed dispersal by animals, as shown by their visually conspicuous seed cones and large seeds presented within a brightly colored fleshy "fruit" of sarcotesta. We tested if this sarcotesta could function as a reward for cycad seed dispersal fauna, by establishing if the toxic compound cycasin, known from the seeds, is absent from the sarcotesta. The Australian cycads Macrozamia miquelii and Cycas ophiolitica were tested (N = 10 individuals per species) using gas chromatography / mass spectrometry. Cycasin was detected at 0.34 % (fresh weight) in seed endosperm of M. miquelii and 0.28 % (fresh weight) in seed endosperm of C. ophiolitica. Cycasin was absent from the sarcotesta of the same propagules (none detected in the case of M. miquelii, and trace quantities detected in sarcotesta of only four of the ten C. ophiolitica propagules). This laboratory finding was supported by field observations of native animals eating the sarcotesta of these cycads but discarding the toxic seed intact. These results suggest cycads are adapted for dispersal fauna capable of swallowing the large, heavy propagules whole, digesting the non-toxic sarcotesta flesh internally, and then voiding the toxic seed intact. Megafauna species such as extant emus or cassowaries, or extinct Pleistocene megafauna such as Genyornis, are plausible candidates for such dispersal. Cycads are an ancient lineage, and the possible antiquity of their megafaunal seed dispersal adaptations are discussed.


Assuntos
Cycas/fisiologia , Cicasina/metabolismo , Extinção Biológica , Frutas/química , Dispersão de Sementes , Sementes/química , Zamiaceae/fisiologia , Animais , Austrália , Tamanho Corporal , Cycas/química , Especificidade da Espécie , Vertebrados , Zamiaceae/química
3.
Neurologia ; 29(9): 517-22, 2014.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-23725821

RESUMO

INTRODUCTION: Cycads are ornamental plants that in some parts of the world are used as fresh food or raw material for producing flour with a high nutritional value. However, they also contain active compounds, including methylazoxymethanol, ß-methylamino-L-alanine, ß-alanine-L-oxalylamino and cycasin, which may produce neurotoxic effects. Some studies have associated consuming cycads and their derivatives with neurodegenerative diseases such as amyotrophic lateral sclerosis/Parkinsonism dementia complex, and other diseases characterised by motor impairment. Therefore, we must not forget that any product, no matter how natural, may present health risks or benefits depending on the chemical compounds it contains and the susceptibility of those who consume it. DEVELOPMENT: We completed a literature analysis to evaluate the neurotoxic properties of cycads and their association with neurological diseases in order to provide structured scientific information that may contribute to preventing health problems in people who use these plants. CONCLUSION: Cycads contain neurotoxic compounds that may contribute to the development of neurological diseases when ingested improperly. We must be mindful of the fact that while some plants have a high nutritional value and may fill the food gap for vulnerable populations, they can also be toxic and have a negative impact on health.


Assuntos
Diamino Aminoácidos/envenenamento , Diamino Aminoácidos/toxicidade , Cycas/envenenamento , Cicasina/envenenamento , Acetato de Metilazoximetanol/análogos & derivados , Doenças Neurodegenerativas/induzido quimicamente , Neurotoxinas/envenenamento , Animais , Agonistas de Aminoácidos Excitatórios/envenenamento , Guam , Humanos , Acetato de Metilazoximetanol/envenenamento , Intoxicação por Plantas
4.
Pak J Biol Sci ; 16(13): 642-6, 2013 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-24505988

RESUMO

This study investigated the effect of a methanolic extract of Vernonia amygdalina (VA) on lipid peroxidation and antioxidant status of the colon of rats maintained on a normal diet containing 5% Cycas revoluta (cycads). Fifty male Wistar albino rats were randomly assigned into five groups of ten experimental animals in a study that lasted for six weeks. One control group was maintained on a normal diet only while another group was fed a normal diet containing 5% cycads. The other three groups were maintained on the normal diet and 5% cycads and orally fed 200 mg VA/kg body weight for 1, 5 or 6 weeks. The results obtained revealed that the level of malondialdehyde (an index of lipid peroxidation) was significantly elevated (p < 0.05) in rats exposed to cycads only compared with the control. However, oral administration of VA in conjunction with exposure to cycads appeared to reduce the extent of lipid peroxidation to values that are not significantly (p > 0.05) different from those of the control. The activity of Superoxide Dismutase (SOD) was significantly reduced (p < 0.05) in the experimental animals fed cycads compared with the controls. Oral administration of VA seemed to counteract the effect of cycads on SOD in the colon as no significant difference (p > 0.05) was observed in rats fed VA compared with the controls. The results of this study suggest that methanolic extract of VA may mitigate the biochemical consequences of cycasin-induced lipid peroxidation in the colon of rats.


Assuntos
Antioxidantes/metabolismo , Colo/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Extratos Vegetais/farmacologia , Vernonia/química , Animais , Colo/metabolismo , Cicasina , Masculino , Malondialdeído/metabolismo , Metanol/química , Extratos Vegetais/química , Folhas de Planta/química , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismo
5.
Int J Environ Res Public Health ; 8(10): 3889-921, 2011 10.
Artigo em Inglês | MEDLINE | ID: mdl-22073019

RESUMO

Western Pacific amyotrophic lateral sclerosis and parkinsonism-dementia complex, a disappearing neurodegenerative disease linked to use of the neurotoxic cycad plant for food and/or medicine, is intensively studied because the neuropathology (tauopathy) is similar to that of Alzheimer's disease. Cycads contain neurotoxic and genotoxic principles, notably cycasin and methylazoxymethanol, the latter sharing chemical relations with nitrosamines, which are derived from nitrates and nitrites in preserved meats and fertilizers, and also used in the rubber and leather industries. This review includes new data that influence understanding of the neurobiological actions of cycad and related genotoxins and the putative mechanisms by which they might trigger neurodegenerative disease.


Assuntos
Esclerose Amiotrófica Lateral/induzido quimicamente , Encéfalo/metabolismo , Cycas/química , Acetato de Metilazoximetanol/análogos & derivados , Mutagênicos/toxicidade , Neurotoxinas/toxicidade , Esclerose Amiotrófica Lateral/epidemiologia , Encéfalo/efeitos dos fármacos , Encéfalo/crescimento & desenvolvimento , Cicasina/farmacologia , Cicasina/toxicidade , Dano ao DNA , Glicosídeos/farmacologia , Glicosídeos/toxicidade , Guam/epidemiologia , Humanos , Acetato de Metilazoximetanol/farmacologia , Acetato de Metilazoximetanol/toxicidade , Mutagênicos/farmacologia , Neurotoxinas/farmacologia , Ilhas do Pacífico/epidemiologia , Tauopatias/epidemiologia , Tauopatias/etiologia
6.
J Chem Ecol ; 37(7): 736-40, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21656034

RESUMO

Aulacoscelinae beetles have an ancient relationship with cycads (Cycadophyta: Zamiaceae), which contain highly toxic azoxyglycoside (AZG) compounds. How these "primitive" leaf beetles deal with such host-derived compounds remains largely unknown. Collections were made of adult Aulacoscelis appendiculata from Zamia cf. elegantissima in Panama, A. vogti from Dioon edule in Mexico, and Janbechynea paradoxa from Zamia boliviana in Bolivia. Total AZG levels were quantified in both cycad leaves and adult beetles by high performance liquid chromatography (HPLC). On average, cycad leaves contained between 0.5-0.8% AZG (frozen weight, FW), while adult beetles feeding on the same leaves contained even higher levels of the compounds (average 0.9-1.5% FW). High AZG levels were isolated from reflex bleeding secreted at the leg joints when beetles were disturbed. Nuclear magnetic resonance and mass spectroscopy identified two AZGs, cycasin and macrozamin, in the reflex bleeding; this is the first account of potentially plant-derived compounds in secretions of the Aulacoscelinae. These data as well as the basal phylogenetic position of the Aulacoscelinae suggest that sequestration of plant secondary metabolites appeared early in leaf beetle evolution.


Assuntos
Secreções Corporais/química , Besouros/química , Folhas de Planta/química , Zamiaceae/química , Animais , Evolução Biológica , Bolívia , Cromatografia Líquida de Alta Pressão , Cicasina/isolamento & purificação , Feminino , Espectroscopia de Ressonância Magnética , Masculino , Espectrometria de Massas , Acetato de Metilazoximetanol/análogos & derivados , Acetato de Metilazoximetanol/isolamento & purificação , México , Panamá
7.
Zhong Yao Cai ; 31(1): 49-51, 2008 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-18589749

RESUMO

OBJECTIVE: To investigate the chemical constituents of the roots of Anemone altaica Fisch. ex C. A. May. METHODS: The constituents of n-BuOH-soluble portion were isolated and purified by means of chromatography. Compounds were identified by their physical characteristics and spectral features. RESULTS: Six compounds were isolated and identified as cimigenol-3-O-beta-D-xylopyranoside (1), cimigenol-3-O-beta-D-xylopyranol (1 -->3)-beta-D-xylopyranoside (2), isolariciresinol-9-O-beta-D-glucopyranoside (3), adenosine (4), uridine (5) and methyl-beta-D-glucopyranoside (6). CONCLUSION: All compounds are isolated from this genus for the first time.


Assuntos
Anemone/química , Glucosídeos/isolamento & purificação , Glicosídeos/isolamento & purificação , Raízes de Plantas/química , Plantas Medicinais/química , Adenosina/química , Adenosina/isolamento & purificação , Cicasina/química , Cicasina/isolamento & purificação , Glucosídeos/química , Glicosídeos/química , Uridina/química , Uridina/isolamento & purificação
10.
Neurology ; 58(6): 956-9, 2002 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-11914415

RESUMO

The Chamorro people of Guam have been afflicted with a complex of neurodegenerative diseases (now known as ALS-PDC) with similarities to ALS, AD, and PD at a far higher rate than other populations throughout the world. Chamorro consumption of flying foxes may have generated sufficiently high cumulative doses of plant neurotoxins to result in ALS-PDC neuropathologies, since the flying foxes forage on neurotoxic cycad seeds.


Assuntos
Esclerose Amiotrófica Lateral/induzido quimicamente , Quirópteros , Cycas/efeitos adversos , Dieta/efeitos adversos , Doença de Alzheimer/induzido quimicamente , Doença de Alzheimer/epidemiologia , Diamino Aminoácidos/efeitos adversos , Esclerose Amiotrófica Lateral/epidemiologia , Animais , Cicasina/efeitos adversos , Feminino , Guam/epidemiologia , Humanos , Incidência , Masculino , Grupo com Ancestrais Oceânicos , Doença de Parkinson/epidemiologia , Doença de Parkinson Secundária/induzido quimicamente , Plantas Tóxicas/efeitos adversos , Sementes/efeitos adversos
12.
J Neurochem ; 70(2): 772-7, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9453573

RESUMO

Although cycasin (methylazoxymethanol beta-D-glucoside) is proposed to be a significant etiological factor for the prototypical neurodegenerative disorder Western Pacific amyotrophic lateral sclerosis and parkinsonism-dementia complex, the mechanism underlying transport of cycasin across the blood-brain barrier (BBB) is unknown. We examined cycasin transport in cultured bovine brain endothelial cells, a major element of the BBB. Cycasin was taken up into endothelial cells in a dose-dependent manner with maximal uptake observed at a concentration of 10 microM. Cycasin uptake was significantly inhibited by alpha-methyl-D-glucoside, a specific analogue for the Na+-dependent glucose transporter (SGLT), by the SGLT inhibitor phlorizin, by replacement of extracellular NaCl with LiCl, and by dinitrophenol (DNP), an inhibitor of energy metabolism. In addition, cycasin produced inward currents in a whole-cell voltage clamp configuration. Peak currents were observed at 10 microM with a trend toward reduction at higher concentrations, and currents were clearly blocked by alpha-methyl-D-glucoside, phlorizin, and DNP. In addition, cycasin never evoked currents in Na+-free extracellular solution. These results suggest that cycasin is selectively transported across brain endothelial cells, possibly across the BBB by a Na+/energy-dependent glucose transporter.


Assuntos
Cicasina/farmacocinética , Endotélio Vascular/metabolismo , Glucose/metabolismo , Proteínas de Transporte de Monossacarídeos/metabolismo , Florizina/farmacologia , Animais , Transporte Biológico/efeitos dos fármacos , Bovinos , Células Cultivadas , Artérias Cerebrais , Córtex Cerebral/irrigação sanguínea , Cicasina/farmacologia , Citocalasina B/farmacologia , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/fisiologia , Glucose/farmacologia , Potenciais da Membrana/efeitos dos fármacos , Metilglucosídeos/farmacologia , Proteínas de Transporte de Monossacarídeos/efeitos dos fármacos , Sódio/farmacologia
14.
Biochim Biophys Acta ; 1289(3): 315-21, 1996 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-8620014

RESUMO

Initial rates of transglucosylation with diglucosides and diglucose-azoxyglycosides as acceptor by cycad beta-glucosidase were tentatively obtained. The formation of beta-1,3 glucosidic linkage was predominant, except for neocycasin A (beta-laminaribioside of methylazoxymethanol, MAM) as an acceptor. With neocycasin A as an acceptor, beta-1,4 and beta-1,6 glucosidic linkages were formed but beta-1,3 linkage was not. Whereas with laminaribiose as acceptor, laminaritriose and triose with beta-1,6 linkage were formed, but triose with beta-1,4 linkage was not. On the other hand, with other diglucoses and neocycasin B (beta-gentiobioside of MAM) as acceptor, all the linkages formed were beta-1,3 glucosidic. The aglycone of azoxyglycosides, MAM, affected the kind of linkages formed in the trisaccharides. When initial rates of the linkage formation of the transglucosylation at 100 mM acceptor were compared with the hydrolysis rates obtained by Lineweaver-Burk plot, the order of formation rates of the di- and tri-glucosides by transglucosylation was the same as obtained for the hydrolysis parameter, kcat/Km. Km values for various substrates could be grouped according to the kind of the linkages (beta-1,3, beta-1,4, and beta-1,6) first split by the enzyme.


Assuntos
Plantas/enzimologia , beta-Glucosidase/metabolismo , Configuração de Carboidratos , Sequência de Carboidratos , Cicasina/química , Cicasina/metabolismo , Glicosídeos/química , Glicosídeos/metabolismo , Glicosilação , Hidrólise , Cinética , Dados de Sequência Molecular , Oligossacarídeos/química , Oligossacarídeos/metabolismo , Especificidade por Substrato
15.
Lett Appl Microbiol ; 22(2): 145-8, 1996 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8936375

RESUMO

beta-Glucosidase was extracted from sonicated Bifidobacterium adolescentis Int-57 and partially purified by Sepharose CL-6B gel-filtration and DEAE-cellulose ion-exchange chromatography. The partially purified enzyme was confirmed to convert cycasin to a mutagen in the Ames and SOS chromotests. beta-Glucosidase negative strains were unable to activate cycasin mutagenically.


Assuntos
Bifidobacterium/enzimologia , Cicasina/metabolismo , Mutagênicos/metabolismo , beta-Glucosidase/metabolismo , Biodegradação Ambiental , Fezes/química , Fermentação , Microbiologia de Alimentos , Humanos , Técnicas In Vitro , Testes de Mutagenicidade , Especificidade por Substrato , beta-Glucosidase/isolamento & purificação
16.
Biochem Pharmacol ; 50(3): 355-65, 1995 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-7646537

RESUMO

Environmental toxins may be risk factors for some forms of diabetes mellitus and neurodegenerative diseases. The medicinal and food use of seed from the cycad plant (Cycas spp.), which contains the genotoxin cycasin, is a proposed etiological factor for amyotrophic lateral sclerosis/Parkinsonism-dementia complex (ALS/PDC), a prototypical neurodegenerative disease found in the western Pacific. Patients with ALS/PDC have a very high prevalence of glucose intolerance and diabetes mellitus (in the range of 50-80%). We investigated whether the cycad plant toxin cycasin (methylazoxymethanol (MAM) beta-D-glucoside) or the aglycone MAM are toxic in vitro to mouse or human pancreatic islets of Langerhans. Mouse pancreatic islets treated for 6 days with cycasin impaired the beta-cell insulin response to glucose, but this effect was reversible after a further 4 days in culture without the toxin. When mouse islets were exposed for 24 hr to MAM/MAM acetate (MAMOAc; 0.1-1.0 mM), there was a dose-dependent impairment in insulin release and glucose metabolism, and a significant decrease in islet insulin and DNA content. At higher MAM/MAMOAc concentrations (1.0 mM), widespread islet cell destruction was observed. Glucose-induced insulin release remained impaired even after removal of MAM and a further culturing for 4 days without the toxin. MAM damages islets by two possible mechanisms: (a) nitric oxide generation, as judged by increased medium nitrite accumulation; and (b) DNA alkylation, as judged by increased levels of O6-methyldeoxyguanosine in cellular DNA. Incubation of mouse islets with hemin (10 or 100 microM), a nitric oxide scavenger, or nicotinamide (5-20 mM) protected beta-cells from a decrease in glucose oxidation by MAM. In separate studies, a 24 hr treatment of human beta-islet cells with MAMOAc (1.0 mM) produced a significant decrease in both insulin content and release in response to glucose. In conclusion, the present data indicate that cycasin and its aglycone MAM impair both rodent and human beta-cell function which may lead to the death of pancreatic islet cells. These data suggest that a "slow toxin" may be a common aetiological factor for both diabetes mellitus and neurodegenerative disease.


Assuntos
Alquilantes/toxicidade , Cicasina/toxicidade , Ilhotas Pancreáticas/efeitos dos fármacos , Diamino Aminoácidos/toxicidade , Animais , DNA/análise , Diabetes Mellitus/induzido quimicamente , Exposição Ambiental , Glucose/metabolismo , Glucose/farmacologia , Humanos , Técnicas In Vitro , Insulina/análise , Insulina/metabolismo , Resistência à Insulina , Secreção de Insulina , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Acetato de Metilazoximetanol/análogos & derivados , Acetato de Metilazoximetanol/toxicidade , Camundongos
17.
Mutat Res ; 346(3): 145-9, 1995 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-7700278

RESUMO

Cycasin, methylazoxymethanol-beta-glucoside, is a naturally occurring carcinogenic compound. The genotoxicity of cycasin was assayed in the Drosophila wing spot test. Cycasin induced small single and large single spots on feeding at 10 mumol/g medium. The presence of these spots indicates that cycasin is genotoxic in Drosophila melanogaster. Microorganisms which showed beta-glucosidase activity for cleaving cycasin to toxic aglycon were isolated from gut flora of the Drosophila larvae. Consequently, the Drosophila wing spot test would be useful for mutagenicity screening of other naturally occurring glucosides.


Assuntos
Cicasina/toxicidade , Mutagênicos/toxicidade , Animais , Biotransformação , Drosophila melanogaster/genética , Feminino , Intestinos/microbiologia , Masculino , Testes de Mutagenicidade , beta-Glucosidase/metabolismo
18.
Ann Nutr Metab ; 39(1): 42-51, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-7872655

RESUMO

Changes in colonic faecal microflora, enzymes of colonic energy metabolism, of cell proliferation and lipid profile in the serum and colon were studied in 48 mice exposed to cycas and fed a Nigeria-type diet. The animals were divided into three diet classes of 16 mice per class, and each class of animals was fed ad libitum either a normal diet, a high-carbohydrate high-fibre (HCF) diet or a high-protein high-fat (HPF) diet. Each diet class was subdivided into two equal groups of 8 animals each. One group was fed a diet type (acted as the diet control) without cycas, and the other group was fed the corresponding diet with cycas. The study period lasted for 3 weeks. The colonic faecal materials were acidified in the HCF-fed mice compared with the other diet-fed mice. Faecal beta-glucuronidase activity was significantly (p < 0.05) increased in the cycas-fed mice compared with the diet controls. Feeding mice with the HPF diet significantly (p < 0.05) increased beta-glucuronidase and mucinase activities. Colonic phosphofructokinase, glucose 6-phosphate dehydrogenase, lactate dehydrogenase and hyaluronidase activities were also significantly (p < 0.05) elevated in the cycas-treated mice. Feeding mice with the HPF diet also significantly (p < 0.05) increased these enzyme activities. Mice fed with the HCF diet significantly (p < 0.05) lowered serum total cholesterol, triglyceride and colonic total lipid. Colonic phosphatidylethanolamine and phosphatidylcholine were significantly (p < 0.05) increased in the HPF-fed mice. This study shows that the HCF diet alters the colonic faecal environment, colonic energy metabolism and hyaluronidase activity in ways which suggest its protective ability against the development of colon cancer in mice.


Assuntos
Neoplasias do Colo/etiologia , Cicasina , Dieta , Animais , Divisão Celular , Colo/metabolismo , Colo/microbiologia , Neoplasias do Colo/epidemiologia , Carboidratos da Dieta/administração & dosagem , Gorduras na Dieta/administração & dosagem , Proteínas na Dieta/administração & dosagem , Metabolismo Energético , Glucuronidase/metabolismo , Concentração de Íons de Hidrogênio , Metabolismo dos Lipídeos , Lipídeos/sangue , Camundongos , Nigéria , Plantas , Polissacarídeo-Liase/metabolismo
19.
J Ethnopharmacol ; 43(2): 67-72, 1994 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-7967657

RESUMO

The underground caudex of the cycad Stangeria eriopus is used extensively by several ethnic groups in South Africa, mainly as an ingredient in magical potions but also as an emetic. An assessment of two main outlets showed that 3410 plants were sold in the month of July 1992; continued usage of this material now threatens the remaining plant populations. A proximate analysis of the caudex material gives high carbohydrate content with only small percentages of fat, protein, fibre and ash. An unusually high content of sodium sulphate may explain the efficacy of Stangeria-containing preparations as an emetic. The phytosterols sitosterol and stigmasterol are present in a 4:1 ratio while the fatty acid component comprises palmitic, oleic, stearic and arachidic acids. Twelve amino acids were identified in the material, including the non-protein amino acids beta-alanine, gamma-aminobutyric acid and pyroglutamic acid. The candidate neurotoxin beta-N-methylamino-L-alanine could not be detected but cycasin is present at the levels of 0.17% and 0.21% in fresh and dry caudex material, respectively and appears to be accompanied by the related toxin, macrozamin.


Assuntos
Magia , Medicina Tradicional Africana , Extratos Vegetais/análise , Plantas Medicinais , Atitude Frente a Saúde , Conservação dos Recursos Naturais , Cicasina/efeitos adversos , Cicasina/isolamento & purificação , Eméticos/isolamento & purificação , Eméticos/uso terapêutico , Cromatografia Gasosa-Espectrometria de Massas , Humanos , África do Sul
20.
Biochim Biophys Acta ; 1193(1): 151-4, 1994 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-8038185

RESUMO

The medicinal and food use of seed from the cycad plant (Cycas spp.), which contains the neurotoxin cycasin, is a proposed etiological factor for amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC), a prototypical neurodegenerative disease found in the western Pacific. Cycasin, the beta-D-glucoside of methylazoxymethanol might enter neurons and other cells via a glucose transporter. Since the intestinal brush-border Na+/glucose cotransporter plays a major role in the absorption of monosaccharides, the following studies were conducted to determine if cycasin, the beta-D-glucoside of methylazoxymethanol, is a substrate for the transporter. We measured the ability of cycasin to (i) inhibit Na+/glucose uptake into rabbit intestinal brush-border membrane vesicles, and (ii) to generate current by the cloned Na+/glucose cotransporter (SGLT1) expressed in Xenopus laevis oocytes. The results show that cycasin inhibits Na(+)-dependent sugar transport in the vesicles, and cycasin generates phlorizin-sensitive currents in oocytes. We conclude that cycasin is a substrate for the intestinal brush-border Na+/glucose cotransporter, albeit with a lower affinity than D-glucose. This suggests that cycasin may be absorbed from the gut lumen by the cotransporter, and as a result either cycasin or the aglycone is presented to the blood-brain barrier for uptake into the brain.


Assuntos
Cicasina/metabolismo , Mucosa Intestinal/metabolismo , Proteínas de Transporte de Monossacarídeos/metabolismo , Animais , Transporte Biológico , Córtex Renal/metabolismo , Microvilosidades/metabolismo , Oócitos/metabolismo , Coelhos , Xenopus
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