330 research outputs found

    Anti-pancreatic cancer potential of secalonic acid derivatives from endophytic fungi isolated from Ocimum basilicum.

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    The word endophyte means "in the plant" and refers to all microorganisms that live in the intercellular spaces of stems, petioles, roots and leaves of plants causing no apparent symptoms of disease. Seven endophytic fungi were isolated from the medicinal plant of Ocimum basilicum L. The fungal strain, labeled as 2L, was cultivated at large scale on the potato dextrose agar semi solid medium and was extracted with ethyl acetate. Normal phase silica gel column chromatography of the ethyl acetate extract afforded ergosterol (1), secalonic acid A (2) and secalonic acid D (3). The structures of these compounds (1-3) were elucidated unequivocally by UV, IR, MS, a series of 1D & 2D NMR analyses. The cytotoxicity of these compounds was evaluated by the MTT assay against human pancreatic cancer cell line. Secalonic acid A (2) and secalonic acid D (3) exhibited significant anti-pancreatic cancer activity with IC 50 values of 7.3 and 1.6 µM, respectively

    Bioactividad de los extractos y aislamiento de los lignanos de las semillas de Centaurea dealbata

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    Centaurea dealbata Willd. (Family: Asteraceae) belongs to the big genus Centaurea that comprises ca. 500 species. Then-hexane, dichloromethane (DCM) and methanol (MeOH) extracts of the seeds of C. dealbata have been assessed forantioxidant activity and general toxicity using, respectively, the DPPH assay, and the brine shrimp lethality assay. Boththe DCM and the MeOH extract showed signifi cant levels of antioxidant activities with an RC50 value 6.8 x 10-2 and4.7 x 10-2 mg/mL, respectively. None of the extracts exhibited any signifi cant general toxicity (LD50 = >1000 mg/mL).Three major bioactive components of the MeOH extract were found to be the lignans, arctigenin, arctiin and matairesinoside.The structures of these lignans were elucidated by comprehensive spectroscopic analyses, and also by directcomparison with the respective published data. This is the fi rst report on the occurrence of arctiin and matairesionl inC. dealbata. The distribution of these lignans within the genus Centaurea has also been presented.La Centaurea dealbata Willd. (familia: Asteraceae) pertenece al género Centaurea, que comprende unas 500 especies.Para evaluar la actividad antioxidante y la toxicidad general de los extractos de n-hexano, diclorometano (DCM)y metanol (MeOH) de las semillas de C. dealbata se han utilizado, respectivamente, el ensayo DPPH y el ensayo deletalidad de gambas en salmuera. Tanto el extracto de DCM como el de MeOH presentaron niveles signifi cativosde actividad antioxidante, con valores de RC50 de 6,8 x 10-2 y 4,7 x 10-2 mg/mL, respectivamente. Ninguno de losextractos presentó una toxicidad general signifi cativa (LD50 = >1000 mg/mL). Se observó que los tres principalescomponentes bioactivos del extracto de MeOH fueron los lignanos arctigenina, arctiina y matairesinosida. Lasestructuras de estos lignanos se dilucidaron mediante análisis espectroscópicos exhaustivos y comparación directacon los datos respectivos publicados. Éste es el primer informe sobre la ocurrencia de arctiina y matairesinol en C.dealbata. También se presenta la distribución de estos lignanos dentro del género Centaurea

    Solar irradiance nowcasting system trial and evaluation for islanded microgrid control purposes

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    The rapid increase in solar photovoltaic (PV) integration into electricity networks introduces technical challenges due to varying PV outputs. Rapid ramp events due to cloud movements are of particular concern for the operation of remote islanded microgrids (IMGs) with high solar PV penetration. PV systems and optionally controllable distributed energy resources (DERs) in IMGs can be operated in an optimised way based on nowcasting (forecasting up to 60 min ahead). This study aims to evaluate the performance under Perth, Western Australian conditions, of an all-sky imager (ASI)-based nowcasting system, installed at Murdoch University in Perth, Western Australia (WA). Nowcast direct normal irradiance (DNI) and global horizontal irradiance (GHI) are inputted into a 5 kWp solar PV system with a direct current (DC) power rating/alternating current (AC) power rating ratio of 1.0. A newly developed classification method provided a simplified irradiance variability classification. The obtained nowcasting system evaluation results show that the nowcasting system’s accuracy decreases with an increase in lead time (LT). Additionally, the nowcasting system’s accuracy is higher when the weather is either mostly clear (with a recorded LT15 mean absolute deviation (MAD) of 0.38 kW) or overcast (with a recorded LT15 MAD of 0.19 kW) than when the weather is intermittently cloudy with varying cloud conditions (with a recorded LT15 MAD of 0.44 kW). With lower errors observed in lower LTs, overall, it might be possible to integrate the nowcasting system into the design of IMG controllers. The overall performance of the nowcasting system at Murdoch University was as expected as it is comparable to the previous evaluations in five other different sites, namely, PSA, La Africana, Evora, Oldenburg, and Julich

    The knowledge of Marma parents in Chittagong Hill Tracts area on the role of play in Early Childhood Development and their contributions towards children's play practices

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    This thesis is submitted in partial fulfillment of the requirements for the degree of Masters of Science in Early Child Development, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (page 44 - 50).A.T.M Shoeb ChowdhuryM. Early Child Developmen

    Bioactivity of the extracts and isolation of lignans and a sesquiterpene from the aerial parts of Centaurea pamphylica (Asteraceae).

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    Centaurea pamphylica Boiss. & Heldr. (Family: Asteraceae), commonly known as 'pamphylia daisy', is a Turkish endemic species of the genus Centaurea that comprises ca. 500 species, many of which have been used as traditional medicines. The n-hexane, dichloromethane (DCM) and methanol (MeOH) extracts of the aerial parts of C. pamphylica were assessed for antioxidant activity and general toxicity using, respectively, the 2,2-diphenyl-1-picrylhydrazyl (DPPH), and the brine shrimp lethality assays. The reversed-phase preparative HPLC and PTLC were used to isolate compounds from the extracts. The structures of these compounds [1-4] were elucidated by spectroscopic means, and also by direct comparison with the respective published data. Both the DCM and the MeOH extract showed significant levels of antioxidant activities with the RC50 values of 72.6 x 10-2 and 47.3 × 10-2 mg/mL, respectively. The MeOH extract exhibited low levels of toxicity towards brine shrimps (LD50 = 125.0 × 10-2 mg/mL). Three major bioactive components of the MeOH extract were matairesinoside [1], arctiin [2] and matairesinol [3]. An eudesmane-type sesquiterpene, pterodontriol [4], was also isolated from the DCM extract. Since reactive oxygen species are important contributors to various ailments, the antioxidant properties of the extracts as well as the isolated compounds may be of medicinal significance. This is the first report on the occurrence of 1-4 in C. pamphylica, and 4 in the genus Centaurea

    Bioactivity of two Turkish endemic centaurea species, and their major constituents.

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    The antioxidant activity, general toxicity and cytotoxicity of the methanol extracts of Centaurea urvillei subs, armata and C. mucronifera have been assessed, respectively, by the DPPH assay, the brine shrimp lethality and the MTT cytotoxicity assays. The reversed-phase HPLC analysis of the methanol extracts afforded two bioactive dibenzylbutyrolactone-type lignans, matairesinoside (1) and arctiin (2). The structures of these lignans were elucidated by comprehensive spectroscopic analyses as well as by the direct comparison of experimental data with respective literature data

    Organochlorine pesticide residues in poultry meats of Bangladesh

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    Forty poultry meat samples from four large companies were analyzed for the presence of organochlorine pesticides. Homogenized samples were mixed with silica sand and anhydrous sodium sulfate, and extracted with ethyl acetate followed by n-hexane: MTBE. Clean up of samples were done by silica sulphuric acid and analyzed by GC-ECD, and confirmed by GC-MS. The limit of detection (LOD) and limit of quantification (LOQ) were 0.5, 0.5 and 0.7, and 2.5, 2.5 and 3.5 ng/g, respectively. The calibration curves were linear and the correlation coefficients (r2) were 0.991, 0.992 and 0.997 for DDE, DDD and DDT, respectively and the recoveries for them were 76%, 78% and 80%. DDT and its metabolites, DDE and DDD were detected in 28 (70%), out of 40 samples and ranged 0.039-0.769 mg/kg

    Oleoquímica I: Estudios sobre la preparación y la estructura de los jabones de litio.

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    Lithium stéarate, palmitate, myristate, laurate, caprate and caprylate were prepared by means of fusion method. Elementary analysis and the infrared absorptions spectra of the prepared lithium soaps as well as their X-ray diffractions and the thermogravimetric analyses were carried out. The anhydrous lithium salts of fatty acids with 12 carbon atoms or less showed thermal stability up to ca. 300 ± 78 °C depending on the chain length. On other hand the salts with 14 carbon atoms or more were decomposed at 126 ± 4 °C leading to formation of lithium carbonate. The homologous lithium soaps had very similar crystal structure among them and their metal -to- oxygen bonds were similar for the acyl chains between 8 and 18 carbons. However the angle of inclination of the molecular axes to the basal plane increased with the decreasing of the number of carbon atoms of the fatty acid chain, as determined by X-ray diffraction. In addition, the ionic character of the metal -to- oxygen bond was enhanced with the decrease of the number of carbon atoms as shown by infrared spectroscopy.Se han preparado estearato, palmitato, miristato, laurato, caprato y caprilato de litio por fusión. Se ha realizado el análisis elemental, los espectros de absorción en el infrarrojo y las difracciones de rayos X de los Jabones de litio preparados, además del análisis termogravimétrico de los mismos. Las sales de litio anhidra de los ácidos con 12 átomos de carbono o menos mostraron una estabilidad térmica hasta los 300 ± 78 °C dependiendo de la longitud de la cadena. Por otro lado las sales con 14 átomos de carbono o más se descompusieron a 126 ± 4 °C formándose carbonato de litio. Los jabones homólogos de litio mostraron una estructura cristalina similar, siendo los enlaces metal-oxígeno del mismo tipo para los ácidos grasos de número de átomos de carbono entre 8 y 18. Sin embargo el ángulo de inclinación que forma la molécula con el plano basal aumentó con la disminución del número de átomos de carbono, lo que se observó por difracción de rayos X. Se comprobó por espectroscopia infrarroja la intensificación del carácter iónico del enlace metal-oxígeno al disminuir el número de átomos de carbono

    El impacto de las inundaciones y las tormentas de arena en el crecimiento y la supervivencia de las plántulas del manglar Avicennia marina en el sur del Mar Rojo

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    Mangroves occur in tropical and subtropical regions, including harsh arid areas. Little is known about how the environmental conditions of deserts influence the ecology of mangrove seedlings. The seedlings of the mangrove Avicennia marina were examined in situ in a natural stand of the southern Red Sea coast of Saudi Arabia to (1) estimate and compare the growth rate of A. marina between selected microhabitats with different tidal exposures, and (2) examine the influence of sandstorms on the growth and survival of the seedlings. Samplings were conducted in four zones established according to their tidal exposure: low tidal exposure (Z1), medium tidal exposure (Z2), high tidal exposure with numerous burrows (Z3), and high tidal exposure with a few or no burrows (Z4). Vertical growth and mortality of the seedlings and selected environmental variables were quantified. The results show that seedling growth rates differed significantly between the sampling zones, the highest growth being found in the high tidal regions (Z3 followed by Z4) and the lowest growth in Z1. Growth rate followed a significant decreasing pattern over time, coinciding with increasing air temperature and decreasing relative humidity. Sandstorms showed a marked increase in July, leading to massive dust deposition that caused extensive mortality of the seedlings by burial. Our study highlights that seedling growth can be affected by the extent of tidal inundation and that sandstorms act as a natural stressor.Los manglares proliferan en regiones tropicales y subtropicales, incluidos los desiertos. Sin embargo, se sabe poco acerca de cómo las condiciones ambientales de los desiertos influyen en la ecología de las plántulas de manglares. Las plántulas del manglar Avicennia marina se examinaron in situ en un manglar natural de la costa sur del Mar Rojo de Arabia Saudita para (1) estimar y comparar la tasa de crecimiento de A. marina entre microhábitats seleccionados con diferente exposición a las mareas, y (2) examinar la influencia de las tormentas de arena en el crecimiento y supervivencia de las plántulas. Los muestreos se realizaron en cuatro zonas establecidas en función de su exposición a las mareas: exposición a las mareas bajas (Z1), exposición a las mareas medias (Z2), exposición a las mareas altas con numerosas madrigueras de cangrejos (Z3) y exposición a las mareas altas pero con pocas o ninguna madriguera (Z4). Se cuantificó el crecimiento vertical y la mortalidad de las plántulas, así como las variables ambientales seleccionadas. Los resultados muestran que las tasas de crecimiento de las plántulas difirieron significativamente entre las zonas de muestreo con el mayor crecimiento encontrado en las regiones de marea alta (Z3 seguida de Z4) y el crecimiento más bajo en Z1. La tasa de crecimiento siguió un patrón decreciente significativo a lo largo del tiempo, que coincidió con el aumento de la temperatura del aire y la disminución de la humedad relativa. Las tormentas de arena aumentaron en julio, causando una deposición masiva de polvo que enterró a las plántulas, desencadenando una gran mortalidad. Nuestro estudio destaca que el crecimiento y la supervivencia de las plántulas pueden verse afectados por la extensión de la inundación de las mareas y las tormentas de arena, actuando como factores de estrés natural
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