Understanding the Biosynthesis of Paxisterol in Lichen-Derived Penicillium aurantiacobrunneum for Production of Fluorinated Derivatives

The U.S. endemic lichen (Niebla homalea)-derived Penicillium aurantiacobrunneum produced a cytotoxic paxisterol derivative named auransterol (2) and epi-citreoviridin (6). Feeding assay using 13C1-labelled sodium acetate not only produced C-13-labelled paxisterol but also confirmed the biosynthetic origin of the compound. The fluorination of bioactive compounds is known to improve pharmacological and pharmacokinetic effects. Our attempt to incorporate the fluorine atom in paxisterol and its derivatives using the fluorinated precursor sodium monofluoroacetate resulted in the isolation of 7-monofluoroacetyl paxisterol (7). The performed culture experiment, as well as the isolation and structure elucidation of the new fluorinated paxisterol, is discussed herein

Ent-homocyclopiamine B, a Prenylated Indole Alkaloid of Biogenetic Interest from the Endophytic Fungus Penicillium concentricum

Ent-homocyclopiamine B (1), a new prenylated indole alkaloid bearing an alicyclic nitro group along with 2-methylbutane-1,2,4-triol (2) were isolated from an endophytic fungus Penicillium concentricum of the liverwort Trichocolea tomentella (Trichocoleaceae). The structure of 1 was elucidated through extensive spectroscopic analyses and comparison with data reported for a structurally related nitro-bearing Penicillium metabolite, clopiamine C (3), which contain an indolizidine ring instead of the quinolizine ring in 1. The new compound, ent-homocyclopiamine B, exhibited slight growth inhibition against Gram-positive bacteria. Based on the reported biosynthesis of related compounds and the isolation of the mevalonic acid derived compound 2-methyl-1,2,4-butanetriol (2), we proposed that ent-homocylopiamine B (1) was biosynthesized from lysine and prenyl group-producing mevalonic pathway

A natural agonist of mosquito TRPA1 from the medicinal plant <i>Cinnamosma fragrans</i> that is toxic, antifeedant, and repellent to the yellow fever mosquito <i>Aedes aegypti</i> - Fig 3

<p><b>Comparative toxic resistance of a pyrethroid-resistant strain of <i>Ae</i>. <i>aegypti</i> (Puerto Rican strain, PR) to CDIAL (A, B) vs. cypermethrin (C,D).</b> The concentration/dose-toxicity relationships of CDIAL against the LVP strain of <i>Ae</i>. <i>aegypti</i> are from <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006265#pntd.0006265.g002" target="_blank">Fig 2</a> (data points are omitted for clarity). A,C) Concentration-toxicity relationships in 1st instar larvae 24 h after adding indicated compound to the rearing water. Efficacy was defined as the percentage of larvae that were dead within 24 h. Values are means ± SEM based on 3–12 independent replicates of 5 larvae per concentration. The EC₅₀ of CDIAL in PR (97.1 μM; 95% CI = 82.4–114.5 μM) was slightly (1.4-fold), but significantly (P < 0.05; F-test), greater than that in LVP (70 nM; 95% CI = 53.8–91.0 μM). The EC₅₀ of cypermethrin in PR (88.0 nM; 95% CI = 46.2–167.7 nM) was dramatically (131-fold) and significantly (P < 0.05; F-test) greater than that in LVP (0.68 nM; 95% CI = 0.34–1.34 nM). B,D) Dose-toxicity relationships in adult females 24 h after applying indicated compound to the thoracic cuticle. Efficacy was defined as the percentage of adults that were incapacitated (dead or flightless) within 24 h. Values are means ± SEM based on 3–8 independent replicates of 10 females per dose. The ED₅₀ of CDIAL in PR (0.45 nmol/mg; 95% CI = 0.34–0.58 nmol/mg) was slightly (1.5-fold), but significantly, (P < 0.05; F-test) greater than that in LVP (0.29 nmol/mg; 95% CI = 0.25–0.34 nmol/mg). The ED₅₀ of cypermethrin in PR (2,685.0 fmol/mg; 95% CI = 1315.0–5484.0 fmol/mg) was dramatically (84-fold) and significantly (P < 0.05; F-test) greater than that in LVP (27.3 fmol/mg; 95% CI = 12.1–61.4 fmol/mg).</p

Capsicodendrin from <i>Cinnamosma fragrans</i> Exhibits Antiproliferative and Cytotoxic Activity in Human Leukemia Cells: Modulation by Glutathione

Capsicodendrin (CPCD, <b>1</b>), an epimeric mixture of a dimeric drimane-type sesquiterpene, is one of the major compounds present in the three endemic species of Madagascan traditional chemopreventive plants: <i>Cinnamosma</i> species (<i>C. fragrans, C. macrocarpa</i>, and <i>C. madagascariensis</i>). Despite the popular use of <i>Cinnamosma</i> in Madagascan traditional medicine and the reported antiproliferative properties of CPCD, elucidation of its mechanism(s) of action is still to be accomplished. In the present study, CPCD at low micromolar concentrations was cytotoxic and induced apoptosis in human myeloid leukemia cells in a time- and concentration-dependent manner. The activity of CPCD in HL-60 and K562 cells was modulated by glutathione (GSH), since depletion of this intracellular thiol-based antioxidant with buthionine sulfoximine resulted in significantly (<i>p</i> < 0.05) greater potency in antiproliferation assays. GSH depletion also significantly potentiated the cytotoxic activity in CPCD-treated human HL-60 cells. Single-cell gel electrophoresis (Comet) assays revealed that GSH depletion in HL-60 cells enhanced the formation of DNA strand breaks in the presence of CPCD. Although CPCD does not contain an obvious Michael acceptor in its structure, ¹H NMR analyses indicated that cinnamodial (<b>2</b>), a monomer of CPCD, was formed within a few hours when dissolved in DMSO-<i>d</i>₆ and interacts with GSH to form a covalent bond via Michael addition at the C-7 carbon. Together the results strongly suggest that <b>2</b> is responsible for the DNA-damaging, pro-apoptotic, and cytotoxic effects of CPCD and that depletion of GSH enhances overall activity by diminishing covalent interaction between GSH and this 2-alkenal decomposition product of CPCD

Effects of CDIAL on <i>TRPA1-/- Ae</i>. <i>aegypti</i>.

<p>A) Antifeedant activity of CDIAL (1.5 mM) in adult females of the parental ORL and <i>TRPA1-/-</i> strains of <i>A</i>. <i>aegypti</i>, as determined via the CAFE choice bioassay. Antifeedant activity was calculated as described in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006265#pntd.0006265.g004" target="_blank">Fig 4</a>. Values are means ± SEM; N = number of independent replicates of 5 mosquitoes each. P value indicates significant difference from ORL strain as determined via an unpaired t-test. B) Dose-toxicity relationship of CDIAL in adult females of ORL and <i>TRPA1-/- Ae</i>. <i>aegypti</i>. Efficacy was defined as the percentage of adults that were incapacitated (dead or flightless) within 24 h. Values are means ± SEM, based on 3–6 independent replicates of 10 mosquitoes per dose. The ED₅₀ values and Hill slopes for the two strains were not significantly different from each other (P > 0.05; F-test). ORL: ED₅₀ = 0.33 nmol/mg (95% C.I. = 0.28–0.38 nmol/mg); Hill slope = 4.77 (95% C.I. = 2.70–6.83). <i>TRPA1-/-</i>: ED₅₀ = 0.30 nmol/mg (95% C.I. = 0.24–0.37 nmol/mg); Hill slope = 2.87 (95% C.I. = 1.16–4.58).</p

Structural comparison of representative drimane sesquiterpenes.

<p>CDIAL, CFRAG, and CMOS were the focus of the present investigation. The conjugation of Ald1 with the double-bond at C-7 and C-8 makes CDIAL a strong electrophile (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006265#pntd.0006265.s001" target="_blank">S1 Fig</a>). The presence of Ald2 attached to a quaternary carbon (C-9) bearing a hydroxyl group also contributes to the electrophilic nature of the molecule (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006265#pntd.0006265.s001" target="_blank">S1 Fig</a>).</p

Dose-toxicity parameters of sesquiterpenes isolated from CINEX on adult females of <i>Ae</i>. <i>aegypti</i> (LVP strain).

<p>^{<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006265#t001fn001" target="_blank">*</a>} = significantly different from CDIAL as determined by a F-test (P < 0.05).</p

Antifeedant activity of CINEX and isolated sesquiterpenes as determined via choice CAFE assays in adult female <i>Ae</i>. <i>aegypti</i> (LVP strain).

<p>Groups of 5 mosquitoes were allowed to feed equally on two capillaries of 10% sucrose with 0.01% trypan blue; the control capillary included 1% acetone (the solvent), and the treatment capillary included 1% acetone and CINEX (0.48 μg/μl) or a sesquiterpene (0.75 or 1.5 mM). In ‘Mock’ experiments, both capillaries included 1% acetone alone. The difference in volume consumed between the capillaries was used to calculate the antifeedant activity (see <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006265#sec002" target="_blank">Methods</a> for details). Values are means ± SEM; N = number of independent replicates of 5 mosquitoes each. Lower-case letters indicate statistical categorization of the means as determined by a one-way ANOVA and Holm-Sidak’s posttest (P < 0.05).</p