162 research outputs found
Discovery of natural antiprotozoals from medicinal plants Saussurea costus and Carica papaya
No full textMedicinal plants have been an important source for the discovery of therapeutic agents for infectious diseases. In order to explore their potential an appropriate selection of plant species is important. In our attempt to find hits targeting antiprotozoal diseases, we utilized an extract library setting, and ethnomedicinal information. A library of 1800 plant and fungal extracts was screened for in vitro effects against Trypanosoma brucei rhodesiense STIB 900 strain and Plasmodium falciparum K1 strain. The ethyl acetate extract of Saussurea costus roots, and the methanolic extract of Carica papaya leaves were selected for further studies. HPLC-based activity profiling enabled the localization and identification of the active constituents of these plants extracts. Sensitive hyphenated analytical methods such as HPLC-PDA-ESI-TOF-MS and microprobe NMR were used for structure elucidation of the isolated compounds. X-ray crystallography was used in combination with electronic circular dichroism to determine the absolute configuration of selected compounds.
The ethyl acetate extract of S. costus roots potently inhibited the growth of T. b. rhodesiense in vitro. HPLC-based activity profiling led to the identification of four sesquiterpene lactones. Three structurally related sesquiterpene lactones that originated from different sources were also investigated. All compounds exhibited profound activity against T. b. rhodesiense with IC50 values between 0.8 – 21.9 µM. Cytotoxicity was tested on rat myoblast L-6 cells, where IC50 values of 1.6 to 19.4 µM were observed, and provided selectivity indices (SI) between 0.5 and 6.5. The most active compounds in this study were the germacranolides costunolide, parthenolide, and eupatoriopicrin.
The leaves of the Indonesian ethnomedicinal plant C. papaya are a known antimalarial remedy. So far, the active principles have not been investigated from a phytochemical and pharmacological point of view. HPLC-based activity profiling of the methanolic extract from C. papaya leaves against P. falciparum led to the discovery of five alkaloids and four flavonol glycosides. All compounds exhibited in vitro antimalarial activity against P. falciparum K1 strain, albeit to varying degrees. Three dimeric alkaloids showed potent activity with IC50 values ranging from 0.2 to 1.8 µM, and SI from 24.2 to 107.5. The isolated flavonol glycosides were less active, with IC50 values between 13.2 – 16.8 µM, and selectivity indices of more than 9. Lower activity was observed for the two monomeric alkaloids (IC50 = 77 µM). Carpaine (IC50 of 0.2 µM; SI of 107.5) was the most interesting compound in this study and was, hence, selected for further evaluation of its in vivo pharmacological properties using a 4-day suppressive assay on mice. However, only a reduction of parasitemia by 11.9% was observed. With the aid of X-ray crystallography and ECD calculation, the absolute configuration for carpaine was established as 1S,11R,13S,14S,24R,26S. Carpaine represents a new scaffold for anti-plasmodial drugs. An analysis of carpaine content by means of UPLC-MS/MS was pursued with 28 leaf samples from Indonesia and one from India. The carpaine content varied from 0.02 to 0.31%
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
Measurement of the polarization amplitudes and triple product asymmetries in the B0s → Φ Φ decay
No full text<p>Using 1.0 fb−1 of pp collision data collected at a centre-of-mass energy of s√=7 TeV with the LHCb detector, measurements of the polarization amplitudes, strong phase difference and triple product asymmetries in the B0s→ϕϕ decay mode are presented. The measured values are</p>
<p>|A0|2=0.365±0.022(stat)±0.012(syst),|A⊥|2=0.291±0.024(stat)±0.010(syst),cos(δ∥)=−0.844±0.068(stat)±0.029(syst),AU=−0.055±0.036(stat)±0.018(syst),AV=0.010±0.036(stat)±0.018(syst).</p>
Analysis of University Researcher Collaboration Networks using co-authorship
No full textSocial network analysis gives evidence for the connections between groups of individuals. It is these connections that channel flow of information and the sharing of knowledge. As universities move towards more interdisciplinary modes of research and funding, an effective network that links its entire cohort of active researchers is vital. This project conducted a co-authorship network analysis and a path length analysis on a small institutional database. The major advantage of our analysis over other similar work is that we used author's background details in supporting our analysis and generated co-authorship graphs with authors' names and groups. The network metrics have been compared and contrasted to similar work conducted with large-scale cross-institutional databases in several domains. We found the most of metrics are not affected by the network size and showed that the ECS community is a small-world network with similar knowledge sharing to those communities formed by an entire discipline
Measurement of the branching fraction
No full textThe B
0
s
→ J/ψK
0
S
branching fraction is measured in a data sample corresponding to 0.41 fb−1
of integrated luminosity collected with the LHCb detector at the LHC. This channel is sensitive to
the penguin contributions affecting the sin 2β measurement from B
0
→ J/ψK
0
S
. The time-integrated
branching fraction is measured to be B(B
0
s
→ J/ψK
0
S
) = (1.83±0.28)×10−5
. This is the most precise
measurement to date
Mosquito Larvicidal Constituents from Lantana Viburnoides SP Viburnoides Var Kisi (A. rich) Verdc (Verbenaceae).
No full text\ud
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Lantana viburnoides sp viburnoides var kisi is used in Tanzania ethnobotanically to repel mosquitoes as well as in traditional medicine for stomach ache relief. Bioassay-guided fractionation and subtraction bioassays of the dichloromethane extract of the root barks were carried out in order to identify the bioactive components for controlling Anopheles gambiae s.s. mosquito larvae. Twenty late III or early IV instar larvae of An. gambiae s.s. were exposed to various concentrations of the plant extracts, fractions, blends and pure compounds, and were assayed in the laboratory by using the protocol of WHO 1996. Mean mortalities were compared using Dunnett's test (p < 0.05) and lethal concentration calculated by Lackfit Inversel of the SAS programme. The crude extract (LC50 = 7.70 ppm in 72 h) and fractions exhibited different level of mosquito larvicidal activity with subtraction of some fractions resulting in activity enhancement. The active fractions contained furanonaphthaquinones regio-isomers (LC50 = 5.48-5.70 ppm in 72 h) and the lantadene triterpenoid camaric acid (LC50 = 6.19 ppm in 72 h) as active principles while the lupane triterpenoid betulinic acid (LC50 < 10 ppm in 72 h) was obtained from the least active fraction. Crude extracts and some fractions had higher or comparable larvicidal activity to the pure compounds. These results demonstrate that L. viburnoides sp viburnoides var kisi extracts may serve as larvicides for managing various mosquito habitats even in their semi-purified form. The isolated compounds can be used as distinct markers in the active extracts or plant materials belonging to the genus Lantana
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Prompt charm production in pp collisions at √<span style="text-decoration:overline">s</span>=7 TeV
No full textCharm production at the LHC in pp collisions at s√=7 TeV is studied with the LHCb detector. The decays D0→K−π+, D+→K−π+π+, D⁎+→D0(K−π+)π+, D+s→ϕ(K−K+)π+, Λ+c→pK−π+, and their charge conjugates are analysed in a data set corresponding to an integrated luminosity of 15 nb−1. Differential cross-sections dσ/dpT are measured for prompt production of the five charmed hadron species in bins of transverse momentum and rapidity in the region 0<pT<8 GeV/c and 2.0<y<4.5. Theoretical predictions are compared to the measured differential cross-sections. The integrated cross-sections of the charm hadrons are computed in the above pT-y range, and their ratios are reported. A combination of the five integrated cross-section measurements gives
σ(cc¯)pT<8 GeV/c,2.0<y<4.5=1419±12(stat)±116(syst)±65(frag) μb,
where the uncertainties are statistical, systematic, and due to the fragmentation functions
Measurement of the cross-section ratio σ(χc2)/σ(χc1) for prompt χc production at √s=7 TeV
No full textThe prompt production of the charmonium χc1 and χc2 mesons has been studied in proton–proton collisions at the Large Hadron Collider at a centre-of-mass energy of . The χc mesons are identified through their decays χc→J/ψγ with J/ψ→μ+μ− using 36 pb−1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for the two χc spin states, σ(χc2)/σ(χc1), has been determined as a function of the J/ψ transverse momentum, , in the range from 2 to 15 GeV/c. The results are in agreement with the next-to-leading order non-relativistic QCD model at high and lie consistently above the pure leading-order colour-singlet prediction
Measurement of the effective B_s^0 -> J/ψ K_S^0 lifetime
No full textThis paper reports the first measurement of the effective B_s^0 -> J/{\psi} K_S^0 lifetime and an updated measurement of its time-integrated branching fraction. Both measurements are performed with a data sample, corresponding to an integrated luminosity of 1.0 fb^{-1} of pp collisions, recorded by the LHCb experiment in 2011 at a centre-of-mass energy of 7 TeV. The results are: tau_J/{\psi}K_S^0 = 1.75 +/- 0.12 (stat) +/- 0.07 (syst) and BR(B_s^0 -> J/{\psi} K_S^0) = (1.97 +/- 0.23) X 10^{-5}.
For the latter measurement, the uncertainty includes both statistical and systematic sources
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