Sector-specific development and policy vulnerability in the Philippines

Ministry of Education, Singapore under its Academic Research Funding Tier

Antiplasmodial β‑Triketone–Flavanone Hybrids from the Flowers of the Australian Tree <i>Corymbia torelliana</i>

The methanol extract of the flowers of the Australian eucalypt tree <i>Corymbia torelliana</i> yielded six new β-triketone–flavanone hybrids, torellianones A–F (<b>1</b>–<b>6</b>), the tetrahydroxycyclohexane torellianol A (<b>7</b>), and known β-triketones (4<i>S</i>)-ficifolidione (<b>8</b>) and (4<i>R</i>)-ficifolidione (<b>9</b>), and β-triketone–flavanones kunzeanone A (<b>10</b>) and kunzeanone B (<b>11</b>). Torellianones A and B, C and D, and E and F were each isolated as inseparable diastereomeric mixtures. Exchange correlations observed in a ROESY spectrum indicated that <b>5</b> and <b>6</b> also interconverted between stable conformers. The structures of <b>1</b>–<b>7</b> were elucidated from the analysis of 1D/2D NMR and MS data. Relative configurations of torellianones C–F and torrellianol A were determined from analysis of ROESY data. Compounds <b>1</b>–<b>10</b> were tested for antiplasmodial activity against a drug-sensitive (3D7) strain of <i>Plasmodium falciparum</i>, with <b>3</b>–<b>6</b> and <b>8</b>–<b>10</b> showing limited antiplasmodial activity, with IC₅₀ values ranging from 3.2 to 16.6 μM

Additional file 1: Figure S1. of Biological characterization of chemically diverse compounds targeting the Plasmodium falciparum coenzyme A synthesis pathway

Retention of gametocyte-infected RBCs after treatment for 2 h (light grey dots) or 24 h (dark grey triangles) with compound concentrations ranging from 10 μM to 0.1 nM. Viability of compound treated gametocytes assessed with Mitotracker Red (MTR), shown as black squares. For all tested compounds, any increased retention rates observed coincided with parasite death, therefore no specific RBC deformability change due to compound treatment could be determined. Figure S2. Effect of test compounds on kinase activity using a radiometric assay (n = 2). (A) Activity of all compounds on PanK at 100 μM; (B) activity of STK668036 on three kinases: PanK, Hexokinase (HK) and Choline kinase (ChK). Asterisks indicate a significant level of inhibition, compared to the control (P < 0.001). Error bars represent standard deviations. Table S1. Activity overview against P. falciparum asexual blood stage forms, early and late stage gametocytes, as well as T. b. brucei and T. cruzi. Table S2. Rescue of inhibitor-treated asexual blood stage P. falciparum, early stage and late stage P. falciparum gametocytes and T. b. brucei trypomastigotes by supplementation with CoA pathway intermediates. Percent rescue averages ± SEM. The rescue experiment was not carried out for inactive compounds (blank spaces). All numeric values are statistically significant (P < 0.001). Table S3. Activity of MMV000570 against Trypanosoma spp., cytotoxicity against a panel of cell lines and selectivity indices (A); the activity of MMV000570 against P. falciparum asexual stages and early stage gametocytes could not be rescued by CoA pathway metabolites; percent rescue averages ± SEM (B). Table S4. Cytotoxicity of test compounds on human cancer cell lines in comparison with reference cell lines and antiplasmodial activity. Figure S3. Concentration response curves displaying cytotoxic effect of MMV665820 on the four mammalian cell lines MCF7 (A), MDA-MB-231 (B), PC3 (C) and 3 T3 (D). (PDF 905 kb

Larvicidal photosensitizing effect of C14 porphyrin.

<p>Mortality of <i>Ae. aegypti</i> larvae (n = 50) incubated with C14 at 28±2°C in the dark for 12 h, and then exposed to light (fluence rate 1.0–4.0 mW/cm²) 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 (n = 3 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 (LC₅₀) of C14 porphyrin.

<p>C14 solutions at 7 increasing concentrations (range 0.03–4.3 µM) were incubated with 6 mg PFP at 28±2°C in the dark for 48 h. <i>Ae. aegypti</i> larvae (3^rd–early 4^th instar, n = 100, 3 replicates) were introduced 12 hours before the beginning of the irradiation (1.0–4.0 mW/cm²).</p

Larvicidal activities of C14 porphyrin-incubated and non incubated PFP.

<p>5 µM 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 (n = 50, 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 1.0–4.0 mW/cm²). Error bars represent standard deviations, (n = 3 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 (400–800 nm) at a fluence rate of 100 mW/cm². 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

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

Influence of irradiation time on C14 porphyrin LC₅₀ on <i>Ae. aegypti</i> larvae.

<p>Error bars represent 95% confidence interval (n = 3 replicates of 100 larvae each). The shaded area in the graph indicates the period of incubation without light (night).</p