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- Abuzeid, Nadir, et al.
(author)
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Antimycobacterial activity of selected medicinal plants traditionally used in Sudan to treat infectious diseases
- 2014
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In: Journal of Ethnopharmacology. - : Elsevier. - 0378-8741 .- 1872-7573. ; 157, s. 134-139
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Journal article (peer-reviewed)abstract
- Ethnopharmacological relevance: The emergence of multidrug-resistant strains of Mycobacterium tuberculosis underscores the need for continuous development of new and efficient methods to determine the susceptibility of isolates of Mycobacterium tuberculosis in the search for novel antimycobacterial agents. Natural products constitute an important source of new drugs, and design and implementation of antimycobacterial susceptibility testing methods are necessary to evaluate the different extracts and compounds. In this study we have explored the antimycobacterial properties of 50 ethanolic extracts from different parts of 46 selected medicinal plants traditionally used in Sudan to treat infectious diseases. Materials and methods: Plants were harvested and ethanolic extracts were prepared. For selected extracts, fractionation with hydrophilic and hydrophobic solvents was undertaken. A luminometry-based assay was used for determination of mycobacterial growth in broth cultures and inside primary human macrophages in the presence or absence of plant extracts and fractions of extracts. Cytotoxicity was also assessed for active fractions of plant extracts. Results: Of the tested extracts, three exhibited a significant inhibitory effect on an avirulent strain of Mycobacterium tubercluosis (H37Ra) at the initial screening doses (125 and 6.25 mu g/ml). These were bark and leaf extracts of Khaya senegalensis and the leaf extract of Rosmarinus officinalis L. Further fractions of these plant extracts were prepared with n-hexane, chloroform, ethyl acetate, n-butanol, ethanol and water, and the activity of these extracts was retained in hydrophobic fractions. Cytotoxicity assays revealed that the chloroform fraction of Khaya senegalensis bark was non-toxic to human monocyte-derived macrophages and other cell types at the concentrations used and hence, further analysis, including assessment of IC50 and intracellular activity was done with this fraction. Conclusion: These results encourage further investigations to identify the active compound(s) within the chloroform fraction of Khaya senegalensis bark. (C) 2014 Elsevier Ireland Ltd. All rights reserved.
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| 3. |
- Pacheco-Contreras, R., et al.
(author)
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Determination of the energy landscape of Pd12Pt1 using a combined genetic algorithm and threshold energy method
- 2013
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In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 3:29, s. 11571-11579
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Journal article (peer-reviewed)abstract
- In this work we present a thorough exploration of the potential energy surface (PES) of Pd-Pt bimetallic nanoparticles at the specific composition Pd12Pt1, using the combination of a genetic algorithm and the threshold method for global optimization and exploration of the barrier structure, employing the semi-empirical Gupta many-body potential for modeling the interatomic interactions. The structural and energetic analysis of Pd12Pt1 nanoparticles, including binding energies (E-b), symmetries and common-neighbor analysis (CNA) allowed us to identify a large set of representative structures of local minima, with an icosahedral motif found to be the putative global minimum for Pd12Pt1. A detailed study of the icosahedral motif was carried out by an exhaustive exploration of low energy isomers, in order to understand qualitatively structural interconversion. 2-D tree (disconnectivity) graphs are plotted to map the structures of minima on the PES of Pd12Pt1. DFT calculations were performed on representative structures to establish the energetic hierarchy and structural stability.
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| 4. |
- Pacheco-Contreras, R., et al.
(author)
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Tetrahelix Conformations and Transformation Pathways in Pt1Pd12 Clusters
- 2012
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In: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 116:21, s. 5235-5239
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Journal article (peer-reviewed)abstract
- The threshold method is used to explore the potential energy surface of the Pt1Pd12 bimetallic cluster, defined by the Gupta semiempirical potential. A set of helical structures, which follow a Bernal tetrahelix pattern, correspond to local minima for the Pt1Pd12 cluster, characterizing the region of the energy landscape where these structures are present. Both right-handed and left-handed chiral forms were discovered in our searches. Energetic and structural details of each of the tetrahelices are reported as well as the corresponding transition probabilities between these structures and with respect to the icosahedron-shaped global minimum structure via a disconnectivity graph analysis.
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