15 research outputs found
Sector-specific development and policy vulnerability in the Philippines
Ministry of Education, Singapore under its Academic Research Funding Tier
Poly-Electrophilic Sesquiterpene Lactones from <i>Vernonia amygdalina</i>: New Members and Differences in Their Mechanism of Thiol Trapping and in Bioactivity
In addition to known compounds, the
leaves of <i>Vernonia
amygdalina</i> afforded the new sesquiterpene lactones 14-<i>O</i>-methylvernolide (<b>2</b>), 3âČ-deoxyvernodalol
(<b>6</b>), and vernomygdalin (<b>8</b>). These and related
compounds were evaluated for modulation of a series of thiol trapping-sensitive
transcription factors (NF-ÎșB, STAT3, and Nrf2), involved in
the maintenance of the chronic inflammatory condition typical of human
degenerative diseases. Vernolide (<b>1</b>) emerged as a potent
inhibitor of STAT3 and NF-ÎșB and showed cytostatic activity
toward the prostate cancer cell line DU45, arresting the cell cycle
at the S phase. The exomethylene lactones are characterized by multiple
Michael acceptor sites, as exemplified by vernolide (<b>1</b>) and vernodalol (<b>5</b>). By using the nuclear magnetic
resonance-based cysteamine assay, the most reactive thiophilic site
could be identified in both compounds, and competitive experiments
qualified vernolide (<b>1</b>) as being more thiophilic than
vernodalol (<b>5</b>), in agreement with the results of the
pharmacological assays
Chemical structure of C14 porphyrin: meso-tri(N-methylpyridyl),meso-mono(N-tetradecylpyridyl)porphine.
<p>Chemical structure of C14 porphyrin: meso-tri(N-methylpyridyl),meso-mono(N-tetradecylpyridyl)porphine.</p
Larvicidal photosensitizing effect of C14 porphyrin.
<p>Mortality of <i>Ae. aegypti</i> larvae (nâ=â50) incubated with C14 at 28±2°C in the dark for 12 h, and then exposed to light (fluence rate 1.0â4.0 mW/cm<sup>2</sup>) for 1 or 6 h. After irradiation, larvae were kept in the dark and larval mortality was monitored daily for 6 days. Arithmetic means of % dead larvae. Error bars represent standard deviation (nâ=â3 replicates of 50 larvae each).</p
Effect of concentration on the absorbance of C14 porphyrin solutions.
<p>Solutions were prepared in PBS. <b>A:</b> absorbance of solutions at the maximum of the Soret band (424 nm); <b>B:</b> absorbance at a wavelength characterized by a lower molar extinction coefficient (404 nm).</p
Median lethal concentrations (LC<sub>50</sub>) of C14 porphyrin.
<p>C14 solutions at 7 increasing concentrations (range 0.03â4.3 ”M) were incubated with 6 mg PFP at 28±2°C in the dark for 48 h. <i>Ae. aegypti</i> larvae (3<sup>rd</sup>âearly 4<sup>th</sup> instar, nâ=â100, 3 replicates) were introduced 12 hours before the beginning of the irradiation (1.0â4.0 mW/cm<sup>2</sup>).</p
Larvicidal activities of C14 porphyrin-incubated and non incubated PFP.
<p>5 ”M C14 porphyrin solutions were used. PFP (70 mg), either pre-incubated with C14 or untreated, was added at the time of introduction of <i>Ae. aegypti</i> larvae (nâ=â50, see <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0001434#s2" target="_blank">methods</a> for details on preparation). Arithmetic means of percent dead, dying and living larvae after within 3 hours irradiation (intensity 1.0â4.0 mW/cm<sup>2</sup>). Error bars represent standard deviations, (nâ=â3 replicates of 50 larvae each). Lowercase letters above bars represent the results of LSD tests carried out independently for each category of larvae (see <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0001434#s2" target="_blank">methods</a>). Different letters above bars indicate statistically different means.</p
Efficiency of singlet oxygen generation by photoactivated C14 porphyrin.
<p>Effect of the irradiation time on the fluorescence properties of a DMA solution (initial absorbance around 1 at 380 nm) and porphyrin solution (initial absorbance around 0.4 at 420 nm) in N,N-dimethyl-formamide (DMF), which was exposed to white light (400â800 nm) at a fluence rate of 100 mW/cm<sup>2</sup>. The spectra taken at 1, 3, 5, 10 and 15 s were overlapping, and the corresponding coloured lines have been omitted from the legend, for clarity.</p
Influence of irradiation time on C14 porphyrin LC<sub>50</sub> on <i>Ae. aegypti</i> larvae.
<p>Error bars represent 95% confidence interval (nâ=â3 replicates of 100 larvae each). The shaded area in the graph indicates the period of incubation without light (night).</p
Residual activity of C14 solutions and formulates on <i>Ae. aegypti</i> larvae.
<p>Mortality was assessed after 12 h irradiation (1.0â4.0 mW/cm<sup>2</sup>).</p><p>*time elapsed between the preparation of the trays and the introduction of 3<sup>rd</sup>â4<sup>th</sup> instar larvae (nâ=â100 larvae; 3 replicates). During this period, trays were incubated in the climatic chamber (12 h photoperiod; 28±2°C; >90% RH). Numbers in parentheses indicate standard deviations.</p>â <p>trays contained 6 mg of untreated larval food in C14 porphyrin solutions at the indicated concentration.</p>âĄ<p>trays contained 6 mg of the indicated formulation in spring water.</p>§<p>one surviving larva was found in the tray. Such larvae were negative for C14 fluorescence at the microscope, therefore they hadn't fed during the experiment.</p