RESUMO
The aqueous extract of Rhizophora mangle bark and its polyphenolic fractions showed remarkable in vitro antiinflammatory activity in a preliminary study. The low molecular weight fraction exhibited cyclooxygenase-2 inhibitory activity while the total aqueous extract and the low molecular weight fraction showed secretory phospholipase A(2) inhibitory activity.
Assuntos
Ciclo-Oxigenase 2/efeitos dos fármacos , Proteínas de Membrana/efeitos dos fármacos , Fosfolipases A/efeitos dos fármacos , Fitoterapia , Extratos Vegetais/farmacologia , Rhizophoraceae , Inibidores de Ciclo-Oxigenase 2/administração & dosagem , Inibidores de Ciclo-Oxigenase 2/farmacologia , Inibidores de Ciclo-Oxigenase 2/uso terapêutico , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/administração & dosagem , Inibidores Enzimáticos/farmacologia , Inibidores Enzimáticos/uso terapêutico , Flavonoides/administração & dosagem , Flavonoides/farmacologia , Flavonoides/uso terapêutico , Humanos , Proteínas de Membrana/antagonistas & inibidores , Fenóis/administração & dosagem , Fenóis/farmacologia , Fenóis/uso terapêutico , Fosfolipases A/antagonistas & inibidores , Casca de Planta , Extratos Vegetais/administração & dosagem , Extratos Vegetais/uso terapêutico , PolifenóisRESUMO
Bioactivity-guided fractionation of the dichloromethane and ethanol extracts from the aerial parts of Artemisia copa led to the isolation of the flavonoids spinacetin, jaceosidin, axillarin, penduletin, tricin and chrysoeriol. These compounds were studied for possible inhibitory activity on the generation of inflammatory mediators in a cell line of mouse macrophages (RAW 264.7) stimulated with lipopolysaccharide. Spinacetin and jaceosidin weakly inhibited nitric oxide production whereas all flavonoids reduced prostaglandin E2 levels to different extents. The most active flavonoid was jaceosidin that inhibited cyclooxygenase-2 activity in a concentration-dependent manner with an IC50 value of 2.8 microM. In addition, the other flavonoids partially inhibited synovial phospholipase A2 activity. These mechanisms may provide a basis for explaining the anti-inflammatory activity of this plant.
Assuntos
Anti-Inflamatórios/farmacologia , Artemisia/química , Flavonoides/farmacologia , Animais , Linhagem Celular , Ciclo-Oxigenase 2/efeitos dos fármacos , Flavonoides/isolamento & purificação , Camundongos , Estrutura Molecular , Fosfolipases A/efeitos dos fármacos , Fosfolipases A2RESUMO
Phospholipase A2 (PLA2) is a family of key enzymes in membrane phospholipid metabolism. In rats, the inhibition of PLA2 activity in the hippocampus was found to impair memory formation. Because memory function is largely dependent on the fluidity of brain membranes, we performed the present study to investigate the effects of in vivo PLA2 inhibition (with PACOCF3) on the fluidity of hippocampal membranes from rats trained in a learning task. Hippocampal tissue from rats injected with 100 microM PACOCF3 showed reduced membrane fluidity as compared to vehicle (p < 0.01), and the reduction of membrane fluidity was highly correlated with PLA2 inhibition (r = .76, p < 0.03). This finding is of interest because reduction of brain membrane fluidity impairs memory formation and both decreased PLA2 activity and reduced membrane fluidity have been reported in the brain from patients with Alzheimer's disease.
Assuntos
Hipocampo/enzimologia , Fluidez de Membrana/fisiologia , Fosfolipases A/metabolismo , Animais , Inibidores Enzimáticos/administração & dosagem , Hipocampo/efeitos dos fármacos , Injeções Intraventriculares , Cetonas/administração & dosagem , Masculino , Fluidez de Membrana/efeitos dos fármacos , Fosfolipases A/efeitos dos fármacos , Fosfolipases A2 , Ratos , Ratos WistarRESUMO
The use of plants as medicine has been referred to since ancient peoples, perhaps as early as Neanderthal man. Plants are a source of many biologically active products and nowadays they are of great interest to the pharmaceutical industry. The study of how people of different culture use plants in particular ways has led to the discovery of important new medicines. In this work, we verify the possible activity of Musa paradisiaca L. (Musaceae) against the toxicity of snake venoms. Musa paradisiaca, an important source of food in the world, has also been reported to be popularly used as an anti-venom. Interaction of Musa paradisiaca extract (MsE) with snake venom proteins has been examined in this study. Phospholipase A2 (PLA2), myotoxic and hemorrhagic activities, including lethality in mice, induced by crotalidae venoms were significantly inhibited when different amounts of MsE were mixed with these venoms before assays. On the other hand, mice that received MsE and venoms without previous mixture or by separated routes were not protected against venom toxicity. Partial chemical characterization of MsE showed the presence of polyphenols and tannins and they are known to non-specifically inactivate proteins. We suggest that these compounds can be responsible for the in vitro inhibition of the toxic effects of snake venoms. In conclusion, according to our results, using mice as experimental model, MsE does not show protection against the toxic effects of snake venoms in vivo, but if was very effective when the experiments were done in vitro.
Assuntos
Venenos de Crotalídeos/antagonistas & inibidores , Hemorragia/prevenção & controle , Musa/metabolismo , Músculo Esquelético/efeitos dos fármacos , Fosfolipases A/efeitos dos fármacos , Extratos Vegetais/farmacologia , Animais , Venenos de Crotalídeos/química , Venenos de Crotalídeos/toxicidade , Avaliação Pré-Clínica de Medicamentos/métodos , Flavonoides/química , Flavonoides/farmacologia , Frutas/química , Frutas/metabolismo , Hemorragia/induzido quimicamente , Masculino , Camundongos , Musa/química , Músculo Esquelético/patologia , Músculo Esquelético/ultraestrutura , Neurotoxinas/efeitos adversos , Neurotoxinas/antagonistas & inibidores , Neurotoxinas/química , Fenóis/química , Fenóis/farmacologia , Fosfolipases A/efeitos adversos , Fosfolipases A2 , Extratos Vegetais/química , Plantas Medicinais , Polifenóis , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Taninos/química , Taninos/farmacologiaRESUMO
Bothropstoxin-I (BthTX-I), a myotoxic Lys49 phospholipase A(2) (PLA(2)) homologue isolated from Bothrops jararacussu snake venom, causes a range of biological effects, including myonecrosis, mouse paw edema, irreversible neuromuscular blockade and lysis of cell cultures. Among eight divalent cations assayed, Mn(2+) was the most effective in reducing mouse paw edema induced by BthTX-I (25 microg). Preincubating BthTX-I with Mn(2+) (1.0mM) reduced mouse paw edema by 70% and myotoxicity by 60% in mice injected i.m. with 50 microg toxin. Mn(2+) (50 microl of a 1mM solution) administered within 1min at the site of toxin injection was still but less effective in antagonising BthTX-I-induced myotoxicity. Mn(2+) (1.0mM) completely prevented BthTX-I (1.4 microM)-induced neuromuscular blockade in the mouse phrenic-nerve diaphragm preparation. Mn(2+) (0.25mM) protected about 85% of NB41A3 cells from lysis when coincubated with BthTX-I (1.0 microM) for 25h. Preincubation with 0.25mM Mn(2+) increased the sensitivity of the cells to subsequent lysis by BthTX-I in the absence of Mn(2+). BthTX-I (1 microM) caused extensive fatty acid release (from 0.8% of the total radiolabeled lipid in control cells to 56% with toxin) when incubated with the NB41A3 cell line for 25h. PLA(2) activity observed in cell cultures after addition of BthTX-I was considerably reduced by 0.25mM Mn(2+). Mn(2+) ions constitute a promising agent to assess the action mechanism and the effects of enzymatic inhibition on the pharmacological activity of Lys49 PLA(2) homologues.
Assuntos
Venenos de Crotalídeos/enzimologia , Venenos de Crotalídeos/farmacologia , Manganês/metabolismo , Fosfolipases A/química , Animais , Bothrops , Cátions Bivalentes/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Diafragma/efeitos dos fármacos , Diafragma/fisiologia , Relação Dose-Resposta a Droga , Edema/induzido quimicamente , Técnicas In Vitro , Injeções Intramusculares , Cinética , Lipídeos/análise , Masculino , Camundongos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/fisiopatologia , Necrose , Neuroblastoma/patologia , Bloqueio Neuromuscular , Fosfolipases A/efeitos dos fármacos , Nervo Frênico/efeitos dos fármacos , Nervo Frênico/fisiologia , Sensibilidade e Especificidade , Células Tumorais CultivadasRESUMO
Bothrops lanceolatus venom contains caseinolytic, phospholipase, esterase and haemorrhagic activities. We have investigated the coagulant and anticoagulant actions of B. lanceolatus venom on human citrated plasma and on purified plasma components. Although B. lanceolatus venom up to 50 microg/ml was unable to clot citrated plasma, at concentrations > or = 5 microg/ml the venom dose-dependently clotted purified human fibrinogen, indicating the presence of a thrombin-like enzyme. Human plasma (final concentration > or = 12.5%) dose-dependently inhibited the venom-induced fibrinogen clotting. This finding suggested that endogenous plasma protease inhibitors can affect the venom's action on fibrinogen. To investigate this possibility, B. lanceolatus venom was incubated with different plasma protease inhibitors and the activity on fibrinogen tested. alpha(2)-Macroglobulin and alpha(1)-antitrypsin did not interfere with the coagulant activity of the venom whereas the antithrombin-III/heparin complex partially inhibited this activity. A non-toxic, acidic phospholipase A(2) purified from B. lanceolatus venom prolonged the activated partial thromboplastin time in human plasma from 39.7+/-0.5 s (control with saline) to 60.2+/-0.9 s with 50 microg of PLA(2) (p<0.001), suggesting an anticoagulant activity associated with this enzyme. This anticoagulant activity may account for some of the effects of the venom on blood coagulation.
Assuntos
Coagulação Sanguínea/efeitos dos fármacos , Bothrops , Venenos de Crotalídeos/toxicidade , Fibrinogênio/efeitos dos fármacos , Fosfolipases A/efeitos dos fármacos , Animais , Venenos de Crotalídeos/enzimologia , Humanos , Fosfolipases A/metabolismoRESUMO
Bothrops asper is responsible for approximately half of the snakebite envenomations in Central America. Despite its medical relevance, only the venom of Costa Rican populations of this species has been studied to some detail, and there is very little information on intraspecies variability in venom composition and toxicity. Venom of B. asper from Guatemala was analyzed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis, and its basic pharmacological activities were investigated with standard laboratory assays. Venom has lethal, hemorrhagic, myotoxic, edema-forming, coagulant, defibrinating and phospholipase A(2) activities, showing a similar toxicological profile to the one previously described for B. asper from Costa Rica. In addition, polyvalent antivenoms produced in Mexico and Costa Rica, and currently used in Guatemala, were tested for their ability to neutralize venom's toxic activities. Both antivenoms were effective against all effects studied, although the Costa Rican product showed higher potency against most activities tested and higher antibody titer against venom components, as determined by enzyme immunoassay. It is suggested that different dosage regimes should be considered when using these antivenoms in B. asper envenomations in Guatemala.
Assuntos
Antivenenos/farmacologia , Bothrops , Venenos de Crotalídeos/antagonistas & inibidores , Venenos de Crotalídeos/toxicidade , Fosfolipases A/efeitos dos fármacos , Animais , Venenos de Crotalídeos/enzimologia , Eletroforese em Gel de Poliacrilamida , Guatemala , Humanos , Dose Letal Mediana , Camundongos , Testes de NeutralizaçãoRESUMO
The effects of crotapotin (a non-toxic and non-enzymatic acid polypeptide naturally complexed with phospholipase A2) and heparin on rat paw edema induced by different secretory phospholipases A2 (sPLA2) have been investigated. The ability of crotapotin to affect the enzymatic activity of the sPLA2(s) have also been evaluated. Secretory PLA2(s) obtained from both snake (Naja naja, Naja mocambique mocambique, Crotalus adamanteus and Crotalus durissus terrificus) and bee (Apis mellifera) venoms as well as that from bovine pancreas were used in this study. Rat paw oedema was induced by a single subplantar injection of the sPLA2s (5-30 microg/paw) in absence and presence of either crotapotin (10-100 microg/paw) or heparin (50 U/paw). Paw volume was measured using a hydroplethysmometer. Phospholipase A2 from Naja naja, Naja mocambique mocambique, Apis mellifera venoms and the basic component of Crotalus durissus terrificus venom all induced dose-dependent rat paw oedema whereas those from Crotalus adamanteus venom and bovine pancreas were ineffective. Paw oedema induced by PLA2(s) from both Naja naja and Apis mellifera venoms was significantly (P < 0.05) inhibited by crotapotin (0.1-100 microg/site) whereas the Naja mocambique mocambique venom PLA2-induced oedema was significantly potentiated (P < 0.05) by this polypeptide (40 microg/site). On the other hand, heparin (50 U/paw) had no effect on the paw oedema induced by PLA2 from Naja naja and Apis mellifera venoms but significantly inhibited the Naja mocambique mocambique venom PLA2-induced oedema. The measurement of the in vitro phospholipasic activity revealed that crotapotin inhibited by 60-70% the enzymatic activities of PLA2(s) from Crotalus adamanteus, Naja mocambique mocambique, Apis mellifera venoms and bovine pancreas. Our results suggest that despite the great homology between the various types of sPLA2 they interact with crotapotin on cell surfaces in different ways leading to either inhibition or potentiation of the paw oedema by a mechanism unrelated to their enzymatic activities. Since heparin reduced paw oedema induced by PLA2 from Naja mocambique mocambique venom it is likely that this sPLA2 is similar to the novel heparin-sensitive PLA2 found in mast cells.
Assuntos
Venenos de Abelha/toxicidade , Crotoxina/farmacologia , Edema/prevenção & controle , Heparina/farmacologia , Fosfolipases A/toxicidade , Venenos de Serpentes/toxicidade , Animais , Edema/induzido quimicamente , Masculino , Fosfolipases A/efeitos dos fármacos , Fosfolipases A/metabolismo , Fosfolipases A2 , Ratos , Ratos WistarRESUMO
Crotamine, a basic, myonecrotic, histamine-releasing neurotoxin, was isolated from Crotalus durissus terrificus venom. Carboxypeptidase A was shown to be activated by crotamine when acting upon N-carbobenzoxyglycil-L-phenylalanine. However the activity of carboxypeptidase B upon the substrate hippuryl-L-arginine was not enhanced by this toxin. Teh basic histamine releasers protamine and compound 48/80 also activated carboxypeptidase A. These three agents activated both alpha-chymotrypsin when acting upon acetyl-L-tyrosine ethyl ester and also five snake venom phospholipase-like myotoxins acting upon egg yolk phosphatidylcholine. These findings suggest that the action of these agents during histamine release may involve the participation of specific intermediary hydrolases which, upon activation, would enhance their cytolytic effects on the sequence of events which lead to granule extrusion and histamine release from mast cells.