28 research outputs found
Three new pentacyclic triterpenoids from twigs of Manniophyton fulvum (Euphorbiaceae)
No full textPhytochemical investigation of the methanol extracts of the twigs of Manniophyton fulvum has led to the isolation and characterization of three new pentacyclic triterpenoids, designated as 3α,28-dihydroxyfriedelan-1-one (1), manniotaraxerol A (3) and manniotaraxerol B (4), along with fourteen known compounds, 3α-hydroxy-1-oxofriedelane (2), betulinic acid (5), friedelin (S1), taraxerol (S2), a mixture of stigmasterol (S3) and β-sitosterol (S4), herranone (S5), docosanoic acid (S6), ursolic acid (S7), nasutin B (S8), bergenin (S9), stigmasterol-3-O-β-Dglucopyranoside (S10), 1,2-di-O-palmitoyl-3-O-(6-sulfo-α-D-quinovopyranosyl)glycerol (S11), and aridanin (S12). The structures of all compounds were determined by comprehensive spectroscopic analyses (1D and 2D NMR, EI and ESI-MS). 3α,28-Dihydroxyfriedelan-1-one (1), 3α-hydroxy-1-oxofriedelane (2), manniotaraxerol A (3), manniotaraxerol B (4), and betulinic acid (5) were evaluated against HeLa (human cervix adenocarcinoma) cancer cells. Manniotaraxerol A (3) showed weak in vitro cytotoxicity with a cell viability value of 49.3%. Betulinic acid (5) also showed significant cytotoxicity against HeLa cell with a cell viability value of 4.0%; the other compounds were inactive in this test
Monochrome symmetric subsets of colored groups
No full textAbstractIn (Electron. J. Combin. 10 (2003); http://www.combinatorics.org/volume-10/Abstracts/v1oi1r28.html), the first author (Yuliya Gryshko) asked three questions. Is it true that every infinite group admitting a 2-coloring without infinite monochromatic symmetric subsets is either almost cyclic (i.e., have a finite index subgroup which is cyclic infinite) or countable locally finite? Does every infinite group G include a monochromatic symmetric subset of any cardinal <G for any finite coloring? Does every uncountable group G such that B(G)< G where B(G)={x∈G:x2=1}, admit a 2-coloring without monochromatic symmetric subsets of cardinality G? We answer the first question positively. Assuming the generalized continuum hypothesis (GCH), we give a positive answer to the second question in the abelian case. Finally, we build a counter-example for the third question and we give a necessary and sufficient condition for an infinite group G to admit 2-coloring without monochromatic symmetric subsets of cardinality G. This generalizes some results of Protasov on infinite abelian groups (Mat. Zametki 59 (1996) 468–471; Dopovidi NAN Ukrain 1 (1999) 54–57)
<b>SCORODOPHLONE A, A NOVEL ALKYLSULFONE FROM THE SEEDS OF <i>SCORODOPHLOEUS ZENKERI</i>. HARMS</b>
No full textA novel alkylsulfone, scorodophlone A 1, from the seeds of Scorodophloeus zenkeri Harms, has been assigned the structure 6-(methylsulfonyl)-1,2,3-dithiazinan-4-one on the basis of its spectroscopic properties. The known compounds α-sophoradiol (12-oleanene-3β,22α-diol), lupeol and sitosterol were also obtained.
KEY WORDS: Scorodophloeus zenkeri, Caesalpiniaceae, Scorodophlone A, Pentacyclic triterpene, Phytosterol
Bull. Chem. Soc. Ethiop. 2006, 20(1), 173-176
Milton Friedman and U.S. monetary history: 1961-2006
No full textThis paper, using extensive archival material from several countries, brings together scattered information about Milton Friedman's views and predictions regarding U.S. monetary policy developments after 1960 (i.e., the period beyond that covered by his and Anna Schwartz's Monetary History of the United States). The author evaluates these interpretations and predictions in light of subsequent events.Friedman, Milton ; Federal Reserve System - History ; Economic history
In Vitro Antioxidant Activity of Extracts and Coumarins from the Stem Bark of Mammea africana Sabine
No full textThe theatre of the organised working class 1830-1930
No full textThis study of the theatre of the British Labour Movement had
its roots in 1985 when History Workshop published a collection
of documents relating to the Workers' Theatre Movements in
Britain and America between 1880 and 1935. In his introductory
essay in Theatres of the Left, Raphael Samuel concludes that
there are no traditions in British Labour Theatre except those
which have been broken or lost, that
There is no continuous history of socialist or
alternative history to be discovered, rather a
succession of moments separated from one another by
a rupture (1).
Since this conclusion was reached, others have repeated
Samuel's assertion in varying forms. So, Andrew Davies talks
of "scanty Chartist theatrical activity" and of the mainstream
lab6ur movement in the 1920s remaining "uninterested in
cultural matters" and Ian Saville asserts that
the conception of a partisan, organised theatre
devoted to spreading the socialist message
throughout the working classes only began to take
shape in Britain in the mid-1920s (2).
Yet a cursory glance at the theatre which preceded the
Workers' Theatre Movement, a glance which Raphael Samuel
provides in his introductory essay on theatre and socialism in
Britain, reveals I a plethora of activity in the labour
movement. From the Chartists and the Owlenites in the nineteenth century, through the Socialist Sunday Schools and
the Socialist League to the Clarion movement, the Independent
Labour Party and the Labour Party, the theatrical activity
pointed to by Samuel is startling in comparison to anything we
can see today. What follows is an attempt to look at some of
those moments, to look at the plays they produced and at both
how and why working class political organisations looked to
the theatre, to try to ascertain if they were indeed no more
than broken threads and if so to try to account for why this
may be the case. It is also an attempt to re-examine some of
our notions of what is political theatre, for since the
discovery of the work of the Workers' Theatre Movement and
subsequently of the Actresses Franchise League much has been
made of these as the starting point of political theatre in
Britain. Yet, for a country with one of the longest traditions
of organised working class movements, such assertions seem at
best strange, at worst dishonest.
One clue as to the reason for such claims can be found in the
characterisation of the theatre of the organised working class
prior to the Workers' Theatre Movement which has become common
currency. It was, in the words of Colin Chambers, primarily
of ethical and anti-militarist rather than directly political",
or in the words of Raphael Samuel:
First, the belief that it is their mission to bring
the working class into contact with "great" art (ie
capitalist art) and second, the tendency to produce
plays which may deal with the misery of the workerss
may even deal with the class struggleg but which
show no way out, and which therefore spread a
feeling of defeat and despair (3).
Such definitions of what is (or rather what is not) political
theatre rest very heavily on a notion that political is most
importantly propaganda. If the theatre that existed in
connection with political organisations prior to 1926 was not
propagandist then it follows for some that it was not
political. What follows is therefore also an attempt to
uncover a different approach, by looking at the groups own
justifications for their involvement in theatrical ventures as
part of the struggle for socialism
Returning culture to peacebuilding : contesting the liberal peace in Sierra Leone
No full textThis thesis investigates the advantages and limitations of applying culture to the analysis of violent conflict and peacebuilding, with a particular focus on liberal peacebuilding in Sierra Leone. While fully aware of the critique of the concept of culture in terms of its uses for the production of difference and ‘otherness,’ it also seeks to respond to the critique of liberal peacebuilding on the account of its low sensitivity towards local culture, which allegedly undermines the peace effort. After a careful examination of the terms of discussion about culture enabled by theoretical approaches to conflict in Chapter 2, the thesis presents a theoretical framework for the analysis of cultural aspects of conflict and peace based on the processes and effects of meaning-generation (Chapter 3), developing the conceptual apparatus and vocabulary for the subsequent empirical study. Instead of bracketing out the recursive nature of cultural theorising, the developed approach embraces the recursive dynamics which arise as a result of cultural ‘embeddedness’ of the analyst and the processes which s/he seeks to elucidate, mirroring similar dynamics in the cultural production of meaning and knowledge. The framework of ‘embedded cultural enquiry’ is then used to analyse the practices of liberal peacebuilding as a particular culture, which shapes the interaction of the liberal peace with its ‘subjects’ and critics as well as framing its reception of the cultural problematic generally (Chapter 4). The application of the analytical framework to the case study investigates the interaction between the liberal peace and ‘local culture,’ offering an alternative reading of the conflict and peace process in Sierra Leone (Chapter 5). The study concludes that a greater attention to cultural meaning-making offers a largely untapped potential for peacebuilding, although any decisions with regard to its deployment will inevitably be made from within an inherently biased cultural perspective
Chemical constituents from the bark of the Cameroonian mahogany Trichilia emetica Vahl (Meliaceae)
No full textTsopgni WDT, Happi GM, Stammler H-G, et al. Chemical constituents from the bark of the Cameroonian mahogany Trichilia emetica Vahl (Meliaceae). Phytochemistry Letters. 2019;33:49-54.Phytochemical investigation of the stem bark extract of Trichilia emetica led to the isolation of two new naturally occurring compounds including a prieurianin-class limonoid named trichirokin (1) and the steroid ergosta-5,24(28)-diene-3S, 16S, 20S-triol (4), along with nine known compounds characterized as rohituka-3 (3), rohituka-9 (2), scopoletin, benzoic acid, protocatechuic acid, lignoceric acid, beta-sitosterol, stigmasterol and beta-sitosterol-3-O-beta-D-glucopyranoside. The crystal structures of rohituka-3 (3) and ergosta-5,24(28)-diene-3S, 16S, 20S-triol (4) are reported here for the first time. The structures of the compounds were elucidated by extensive spectroscopic and spectrometric data interpretation. The stereochemistry of compound 1 was established on the basis of its NOESY spectrum and the comparison of its optical rotation value with that of its congener 2. None of the reported compounds displayed antibacterial or cytotoxic activity
Biological activities of plant extracts from Ficus elastica and Selaginella vogelli : An antimalarial, antitrypanosomal and cytotoxity evaluation
No full textThe cytotoxic, antiplasmodial, and antitrypanosomal activities of two medicinal plants traditionally used in Cameroon were evaluated. Wood of Ficus elastica Roxb. ex Hornem. aerial roots (Moraceae) and Selaginella vogelii Spring (Selaginellaceae) leaves were collected from two different sites in Cameroon. In vitro cell-growth inhibition activities were assessed on methanol extract of plant materials against Plasmodium falciparum strain 3D7 and Trypanosoma brucei brucei, as well as against HeLa human cervical carcinoma cells. Criteria for activity were an IC50 value 10 μg/mL. The extract of S. vogelii did not significantly reduce the viability of P. falciparum at a concentration of 25 μg/mL but dramatically affected the trypanosome growth with an IC50 of 2.4 μg/mL. In contrast, at the same concentration, the extract of F. elastica exhibited plasmodiacidal activity (IC50 value of 9.5 μg/mL) and trypanocidal (IC50 value of 0.9 μg/mL) activity. Both extracts presented low cytotoxic effects on HeLa cancer cell line. These results indicate that the selected medicinal plants could be further investigated for identifying compounds that may be responsible for the observed activities and that may represent new leads in parasitical drug discovery
Compound isolation and biological activities of Piptadeniastrum africanum (hook.f.) Brennan roots
No full textEthnopharmacological relevance: The dicotyledonous plant Piptadeniastrum africanum (hook.f.) Brennan (Fabaceae) is used in traditional medicine to treat various human complaints including bronchitis, coughing, urino-genital ailments, meningitis, abdominal pain, treatment of wounds, malaria and gastrointestinal ailments, and is used as a purgative and worm expeller. Aim of the study: The present study describes the phytochemical investigation and the determination of the antimicrobial, antiplasmodial and antitrypanosomal activities of crude extract, fractions and compounds extracted from Piptadeniastrum africanum roots. Materials and methods: Isolated compounds were obtained using several chromatographic techniques. The structures of all compounds were determined by comprehensive spectroscopic analyses (1D and 2D NMR) and by comparing their NMR data with those found in literature. In vitro antimicrobial activity of samples was evaluated using the microdilution method on bacterial (Escherichia coli, Proteus mirabilis, Staphylococcus aureus) and fungal (Candida krusei) strains, while in vitro cell-growth inhibition activities were assessed against two parasites (Trypanosoma brucei brucei and Plasmodium falciparum strain 3D7). The cytotoxicity properties of samples were assayed against HeLa human cervical carcinoma. Results: Five compounds were isolated and identified as: tricosanol 1, 5α-stigmasta-7,22-dien-3-β-ol 2, betulinic acid 3, oleanolic acid 4 and piptadenamide 5. This is the first report of the isolation of these five compounds from the roots of P. africanum. The (Hex:EtOAc 50:50) fraction exhibited moderate antibacterial activity against P. mirabilis (MIC 250 μg/mL), while the other fractions and isolated compounds had weak antimicrobial activities. Only the EtOAc fraction presented a moderate antimalarial activity with an IC50 of 16.5 μg/mL. The MeOH crude extract and three fractions (Hexane, Hexane-EtOAc 25% and EtOAc-MeOH 25%) exhibited significant trypanocidal activity with IC50 values of 3.0, 37.5, 3.8 and 9.5 μg/mL, respectively. Conclusion: These results demonstrated a scientific rational of the traditional uses of P. africanum and indicate that this plant should be further investigated to identify some of the chemical components that exhibited the activities reported in this study and therefore may constitute new lead candidates in parasiticidal drug discovery.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
