RESUMEN
The aim of this study was to examine the antinociceptive potential of leaves of Ixora coccinea (family: Rubeaceae). One of four doses (500, 750, 1000 or 1500 mg/kg, n = 8/dose) of aqueous leaf extract (ALE) or 1 ml of distilled water was orally administered to male rats and antinociceptive activity was ascertained using three models ofnociception (tail flick, hot plate and formalin tests). The results showed that ALE possesses considerable antinociceptive activity (when evaluated in hot plate and formalin test but not in tail flick test). The antinociceptive activity of the ALE had a rapid onset (within 1h) and a fairly long duration of action (up to 5 h) with a peak effect at 3 h. Further, the antinociceptive activity was dose-dependent and was not associated with harmful side-effects or toxicity even following subchronic administration. The antinociceptive action was mediated centrally at the supraspinal level mainly via dopaminergic mechanism. In addition, it is likely that antioxidant activity of the ALE could have played an auxiliary role in inducing antinociception. Dopaminergic and antioxidative activities of ALE could arise, respectively, from its quaternary base alkaloid and flavonoid constituents.
Asunto(s)
Analgésicos/farmacología , Extractos Vegetales , Hojas de la Planta/metabolismo , Alanina Transaminasa/sangre , Animales , Antioxidantes/metabolismo , Aspartato Aminotransferasas/sangre , Membrana Celular/metabolismo , Creatinina/sangre , Dopamina/metabolismo , Femenino , Fertilidad/efectos de los fármacos , Formaldehído/metabolismo , Calor , Masculino , Músculos/efectos de los fármacos , Músculos/metabolismo , Dolor , Prostaglandinas/biosíntesis , Prostaglandinas/metabolismo , Distribución Aleatoria , Ratas , Receptores Dopaminérgicos/metabolismo , Receptores Opioides/metabolismo , Factores de Tiempo , Urea/metabolismo , Agua/metabolismoRESUMEN
In Sri Lankan folk medicine, the leaves of Crinum bulbispermum Burm. (Family: Amaryllidaceae) are claimed to be useful for earache, which is suggestive of antinociceptive activity. The aim of this study was to examine scientifically the antinociceptive activity of Crinum bulbispermum leaves. One of three doses (1000, 1500 and 3000 mg/kg, N=6/group) of aqueous leaf extract (ALE) or 1 ml of distilled water (DW) (vehicle) (N=6) was orally administered to male rats and antinociceptive activity was determined using three models of nociception (tail flick, hot plate and formalin tests). In the hot plate test, slight (18-42%) but significant (P<0.05) overall prolongation of reaction time was evident up to 4h. In the hot plate test, reaction time was markedly (84-121%) and significantly increased by the high dose up to 3h. In contrast, in the formalin test, the high and mid doses significantly impaired the number of lickings and time spent on licking at both phases, whilst the lower dose impaired only the time spent on licking at the late phase. Collectively these results suggest that the antinociception is mediated both spinally and supraspinally and is effective against phasic and continuous non-inflammatory/inflammatory pain. Additionally, the ALE had antihyperalgesic activity. The antinociception of the ALE appear to results from opioid mechanisms, sedation and antioxidant activities. Unfortunately, ALE is mild to moderately toxic.
Asunto(s)
Analgésicos/aislamiento & purificación , Analgésicos/farmacología , Crinum , Dimensión del Dolor/efectos de los fármacos , Administración Oral , Animales , Masculino , Dimensión del Dolor/métodos , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/farmacología , Hojas de la Planta , RatasRESUMEN
Barringtonia racemosa Linn. (Family Lecythidaceae) possess several bioactivities and is used in traditional medicine of Sri Lanka, but its analgesic potential has not been investigated so far. The aim of this study was therefore to examine the antinociceptive potential of an aqueous bark extract (500, 750, 1000 or 1500 mg/kg) of B. racemosa in male rats using three models of nociception (tail flick, hot plate and formalin tests). The results showed that the extract has antinociceptive activity (when evaluated in hot plate and formalin test but not in tail flick test) without producing unwanted side effects or toxicity. Further, the extract did not alter fertility, gestational length, peri- and neonatal development and appears to be non-teratogenic. The antinociceptive effect was mediated mainly via opioid mechanisms. Such inhibition of pain could arise from phenolic and steroidal constituents as was shown to be present in the extract.
Asunto(s)
Analgésicos/toxicidad , Barringtonia , Dolor/tratamiento farmacológico , Corteza de la Planta , Extractos Vegetales/toxicidad , Administración Oral , Analgésicos/aislamiento & purificación , Analgésicos/uso terapéutico , Animales , Etnofarmacología , Fertilidad/efectos de los fármacos , Masculino , Fitoterapia , Extractos Vegetales/uso terapéutico , RatasRESUMEN
Scopoletin (7-hydroxy-6-methoxy coumarin) which inhibited the conidial germination of Corynespora cassiicola was isolated from the uninfected mature leaves of Hevea brasiliensis. Scopoletin was not detected in uninfected immature rubber leaves. The immature leaves produced scopoletin after being infected with C. cassiicola. The concentration of scopoletin in infected leaves was higher than in uninfected mature leaves. Scopoletin also inhibited the conidial germination of other fungal pathogens of H. brasiliensis. However, no correlation was observed between scopoletin accumulation and clonal resistance.
Asunto(s)
Ascomicetos/efectos de los fármacos , Hevea/metabolismo , Hevea/microbiología , Hojas de la Planta/química , Escopoletina/aislamiento & purificación , Escopoletina/farmacología , Antifúngicos/aislamiento & purificación , Antifúngicos/metabolismo , Antifúngicos/farmacología , Ascomicetos/crecimiento & desarrollo , Hevea/química , Enfermedades de las Plantas/microbiología , Hojas de la Planta/metabolismo , Hojas de la Planta/microbiología , Escopoletina/metabolismoRESUMEN
The hexane extract of the stem bark of Gordonia dassanayakei showed high antifungal activity against plant pathogenic fungi Curvularia sp., Colletotrichum gloeosporioides, Rhizoctonia solani, Corynespora cassiicola, and Fusarium sp. A compound responsible for the antifungal activity was isolated and identified as 3-formyl-2,4-dihydroxy-6-methylbenzoic acid 3-hydroxy-4-(methoxycarbonyl)-2,5-dimethylphenyl ester (1).
Asunto(s)
Antifúngicos/farmacología , Ericales , Hongos/efectos de los fármacos , Plantas Medicinales , Humanos , Pruebas de Sensibilidad Microbiana , Extractos Vegetales/farmacología , Tallos de la PlantaRESUMEN
Beta-Secondary and solvent deuterium kinetic isotope effects have been determined for the steady-state kinetic parameters V/K and V for turnover of a depsipeptide substrate, m-[[(phenylacetyl)glycyl]-oxy]benzoic acid, and of a beta-lactam substrate, penicillanic acid, by three typical class A beta-lactamases and a class C beta-lactamase. The isotope effects on alkaline hydrolysis of these substrates have been used as a frame of reference. The effect of the transition state conformation of the substrates in determining the beta-secondary isotope effects has been explicitly considered. The inverse beta-secondary isotope effects on both V/K and V for the class A enzymes with both substrates indicate transition states where the carbonyl group of the scissile bond has become tetrahedral and therefore reflect typical acyl-transfer transition states. The solvent isotope effects indicate that enzyme deacylation (as reflected in V for the Staphylococcus aureus PC1 beta-lactamase) may be a classical general-base-catalyzed hydrolysis but that there is little proton motion in the enzyme acylation transition state (as revealed by V/K) for the TEM beta-lactamase and Bacillus cereus beta-lactamase I. These results provide kinetic support for the conjecture made on structural grounds that class A beta-lactamases employ an asymmetric double-displacement mechanism. The isotope effects on V/K for the class C beta-lactamase of Enterobacter cloacae P99 suggest an acyl-transfer transition state for the penicillin, although, as for the class A enzymes, without significant proton motion. On the other hand, the V/K transition state for depsipeptide does not seem to involve covalent chemistry. Suggestive of this conclusion are the measured beta-secondary isotope effect of 1,002 +/- 0.012 and the inverse solvent isotope effect. These results provide an example of a significant difference between the kinetics of turnover of a beta-lactam and a depsipeptide by a beta-lactamase. The V transition state for both substrates with the P99 beta-lactamase probably involves acyl-transfer (deacylation) where the conformation of the acyl-enzyme is closely restricted. The conformations of acyl-enzymes of the PC1 and P99 beta-lactamases correlate to the (different) dispositions of general base catalysts at their active sites.