Antimicrobial and antioxidant properties of methanol extract, fractions and compounds from the stem bark of Entada abyssinica Stend ex A. Satabie

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to evaluate the antimicrobial and antioxidant activities of the methanol extract, fractions and isolated compounds from <it>Entada abyssinica </it>stem bark, plant used traditionally against gastrointestinal infections.</p> <p>Methods</p> <p>The methanol extract of <it>E. abyssinica </it>stem bark was pre-dissolved in a mixture of methanol and water, and then partitioned between <it>n</it>-hexane, ethyl acetate and <it>n</it>-butanol. The ethyl acetate portion was fractionated by column chromatography and the structures of isolated compounds elucidated by analysis of spectroscopic data and comparison with literature data. Antimicrobial activity was assayed by broth microdilution techniques on bacteria and yeasts. The antioxidant activity was determined by DPPH radical scavenging method.</p> <p>Results</p> <p>Four known compounds [(5<it>S</it>,6<it>R</it>,8a<it>R</it>)-5-(carboxymethyl)-3,4,4a,5,6,7,8,8a-octahydro-5,6,8a-trimethylnaphthalenecarboxylic acid (<b>1</b>), methyl 3,4,5-trihydroxybenzoate (<b>2</b>), benzene-1,2,3-triol (<b>3</b>) and 2,3-dihydroxypropyltriacontanoate (<b>4</b>)] were isolated. Compared to the methanol extract, fractionation increased the antibacterial activities of the <it>n</it>-hexane and ethyl acetate fractions, while the antifungal activities increased in ethyl acetate, <it>n</it>-butanol and aqueous residue fractions. The isolated compounds were generally more active on bacteria (9.7 to 156.2 μg/ml) than yeasts (78.1 to 312.5 μg/ml). Apart from compound <b>1</b>, the three others displayed DPPH^·scavenging activity (RSa), with RSa₅₀values of 1.45 and 1.60 μg/ml.</p> <p>Conclusion</p> <p>The results obtained from this study support the ethnomedicinal use of <it>E. abyssinica </it>in the treatment of gastrointestinal infections and the isolated compounds could be useful in the standardisation of antimicrobial phytomedicine from this plant.</p

Spatiotemporal climate and vegetation greenness changes and their nexus for Dhidhessa River Basin, Ethiopia

Background Understanding spatiotemporal climate and vegetation changes and their nexus is key for designing climate change adaptation strategies at a local scale. However, such a study is lacking in many basins of Ethiopia. The objectives of this study were (i) to analyze temperature, rainfall and vegetation greenness trends and (ii) determine the spatial relationship of climate variables and vegetation greenness, characterized using Normalized Difference in Vegetation Index (NDVI), for the Dhidhessa River Basin (DRB). Quality checked high spatial resolution satellite datasets were used for the study. Mann–Kendall test and Sen’s slope method were used for the trend analysis. The spatial relationship between climate change and NDVI was analyzed using geographically weighted regression (GWR) technique. Results According to the study, past and future climate trend analysis generally showed wetting and warming for the DRB where the degree of trends varies for the different time and spatial scales. A seasonal shift in rainfall was also observed for the basin. These findings informed that there will be a negative impact on rain-fed agriculture and water availability in the basin. Besides, NDVI trends analysis generally showed greening for most climatic zones for the annual and main rainy season timescales. However, no NDVI trends were observed in all timescales for cool sub-humid, tepid humid and warm humid climatic zones. The increasing NDVI trends could be attributed to agroforestry practices but do not necessarily indicate improved forest coverage for the basin. The change in NDVI was positively correlated to rainfall (r2 = 0.62) and negatively correlated to the minimum (r2 = 0.58) and maximum (r2 = 0.45) temperature. The study revealed a strong interaction between the climate variables and vegetation greenness for the basin that further influences the biophysical processes of the land surface like the hydrologic responses of a basin. Conclusion The study concluded that the trend in climate and vegetation greenness varies spatiotemporally for the DRB. Besides, the climate change and its strong relationship with vegetation greenness observed in this study will further affect the biophysical and environmental processes in the study area; mostly negatively on agricultural and water resource sectors. Thus, this study provides helpful information to device climate change adaptation strategies at a local scale

Keeping diversity alive : an Ethiopian perspective

In IDL-3258

Improvement of Durum Wheat Yield and Associated Effects on Morpho-Phsiological Characters

Six durum wheat ( Triticum turgidum var. durum ) cultivars released in the central highlands of Ethiopia from 1967 to 1992, were evaluated to estimate progress in improving grain yield, and to determine changes in crop morphological and physiological attributes. The six durum wheat cultivars differed in all crop parameters studied. Over the 25 year period represented by the varietal releases, grain yield increased by 68 kg ha-1y-1 (1.58%y-1). Grain yield of durum wheat was positively correlated with harvest index, grains m-2, grains spike-1, grains spikelet-1, and thousand grain weight, all of which increased significantly over time. Spike density (ie., spikes m-2) decreased slightly while the other parameters did not exhibit significant temporal trends. Protein yield increased over time along with grain yield, while grain protein was unchanged. The national durum improvement programme has substantially improved the grain yield of rainfed durum wheat by increasing the magnitude of the grain sink and the efficiency of assimilate partitioning into grain. Durum breeders in Ethiopia should emphasise spike fertility and kernel size as reliable selection criteria for continued improvement in yield potential

Improvement of Durum Wheat Yield and Associated Effects on Morpho-Phsiological Characters

Six durum wheat ( Triticum turgidum var. durum ) cultivars released in the central highlands of Ethiopia from 1967 to 1992, were evaluated to estimate progress in improving grain yield, and to determine changes in crop morphological and physiological attributes. The six durum wheat cultivars differed in all crop parameters studied. Over the 25 year period represented by the varietal releases, grain yield increased by 68 kg ha-1y-1 (1.58%y-1). Grain yield of durum wheat was positively correlated with harvest index, grains m-2, grains spike-1, grains spikelet-1, and thousand grain weight, all of which increased significantly over time. Spike density (ie., spikes m-2) decreased slightly while the other parameters did not exhibit significant temporal trends. Protein yield increased over time along with grain yield, while grain protein was unchanged. The national durum improvement programme has substantially improved the grain yield of rainfed durum wheat by increasing the magnitude of the grain sink and the efficiency of assimilate partitioning into grain. Durum breeders in Ethiopia should emphasise spike fertility and kernel size as reliable selection criteria for continued improvement in yield potential

Farmers of the future: a strategy for action

Much of this book is the product of an international round-table discussion held in Nairobi in May 2002 focussing on ways in which different partners will complement and support Farmers of the Future initiative. It details the initiative's strategy for the improvement of natural resource management education. The strategy encompasses 10 cornerstones that seek to enhance the relevance and impact of basic education programmes. These cornerstones have been identified as fundamental conditions for effective integration of natural resource mangement in basic education