Penicillixanthone A, a marine-derived dual-coreceptor antagonist as anti-HIV-1 agent

<p>Marine micro-organisms have been proven to be excellent sources of bioactive compounds against HIV-1. Several natural products obtained from marine-derived <i>Aspergillus</i> fungi were screened for their activities to inhibit HIV-1 infection. Penicillixanthone A (PXA), a natural xanthone dimer from jellyfish-derived fungus <i>Aspergillus fumigates</i>, displayed potent anti-HIV-1 activity by inhibiting infection against CCR5-tropic HIV-1 SF162 and CXCR4-tropic HIV-1 NL4-3, with IC₅₀ of 0.36 and 0.26 μM, respectively. Molecular docking study was conducted to understand the possible binding mode of PXA with the CCR5/CXCR4. The results revealed that, the marine-derived PXA, as a CCR5/CXCR4 dual-coreceptor antagonist, presents a new type of potential lead product for the development of anti-HIV therapeutics.</p

The identity of amino acid signatures in the proteins of pandemic IAVs and human, swine, and avian IAVs.

<p>The identity of amino acid signatures in the proteins of pandemic IAVs and human, swine, and avian IAVs.</p

Schematic representation of the functional domains with mutated residues in the 2009 H1N1pdm proteins.

<p><b>Left panels</b>: bird's eye view of protein structures of 2009 H1N1pdm collected at the pre-epidemic period in 2009; <b>Middle panels</b>: close-up view of the mutated amino acid residues in proteins of 2009 H1N1pdm collected at the pre-epidemic period in 2009; <b>Right panels</b>: close-up view of the mutated amino acid residues in proteins of 2009 H1N1pdm collected at the late period in 2009. The amino acid numberings were based on influenza virus A/Puerto Rico/8/1934 (H1N1) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0009549#pone.0009549-Chen1" target="_blank">[6]</a>. The residues in viruses collected in the pre-epidemic period are colored in red, and those in viruses collected in the late period are colored in yellow. <b>A–C:</b> NP trimer and monomer. <b>D–F:</b> NA tetramer and monomer. Drug target domain (DTD) is highlighted in dark blue. H260 [274 in A/Vietnam/1203/04(H5N1)] is a critical residue for the NA inhibitor, oseltamivir. NA H274Y mutation results in resistance of 2009 H1N1pdm and other influenza viruses to oseltamivir. <b>G–I</b>: HA trimer and monomer. Receptor binding domain (RBD) was highlighted in wheat color, while other part is in green color. <b>J–L</b>: Dimer and monomer of effector domain (ED) in NS1.</p

Comparison of the amino acid signatures in the proteins of 2009 H1N1pdm with those in human, swine, and avian IAVs, as well as those causing past influenza pandemics.

<p>Note: Only the dominant residues were listed. The human-like amino acid signatures in the 2009 H1N1pdm were highlighted in bold and italic.</p

Chemical structures of polyanion-based microbicides and GAGs.

<p>Chemical structures of the molecules include cellulose sulfate (A), λ-carrageenan (B), CAP (C), polystyrene sulfonate (D), PRO 2000 (E), heparin sulfate (F) and methyl cellulose (G).</p

Mutation trend analysis of signature and non-signature amino acid residues in the functional domains of the proteins of 2009 H1N1pdm during the influenza pandemic in 2009.

<p>Note: the number in brackets indicates the percent (%) of sequences with the mutated amino acid in total number of the sequences collected in the period; ‘-’ means unavailable in non-H1N1 virus.</p

A brief schematic of the assays for testing the effect of polyanions on HIV-1 infection in the presence of PAP248-286 or SE-F.

<p>Polyanions at graded concentration was mixed with an indicated concentration of PAP248-286 or SE-F at an indicated interval with agitation as described in the “<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059777#s2" target="_blank">Materials and Methods</a>”. After centrifugation, the supernatants were collected for testing the inhibitory activity of the unbounded polyanions on HIV-1 infection. The pellets containing the PAP248-286 (SEVI) - or SE-F-derived amyloid fibrils were re-suspended in 100 µl medium for testing the enhancing effect on HIV-1 infection.</p

Enhancement of HIV-1 infection of SE-F in the presence of polyanions.

<p>SE-F or PBS (as a control) was agitated with various polyanions at graded concentration for 5 h. The pellet portion of the mixture was mixed with R5 tropic (A) and X4 tropic viruses (B), respectively. The mixtures were added to TZM-b1 cells. After culture at 37°C for 3 h, the medium was replaced. Luciferase activity was detected 72 h later. The experiment was repeated once and similar results were obtained. Shown are average values (± standard deviations) of triplicate measurements of a representative experiment. *vs. HIV-1 in SE, <i>P</i><0.05 by <i>t</i>-test.</p

Time courses of PAP248-286 aggregation in the absence or presence of polyanionic candidate microbicides.

<p>2 mg/ml PAP248-286 was agitated at 37°C and 1200 rpm in the presence or absence of various polyanions (30 µg/ml). The status of peptide aggregation is monitored by Thioflavin T staining (A) or Congo red staining (B). The facilitation of the fibrillogenesis of PAP248-286 mediated by cellulose sulfate is dose-dependant as revealed by Thioflavin T staining (C) and Congo red staining (D). The data presented were the median values obtained from one experiment performed in triplicate. Experiments were repeated once that yielded similar trends.</p

No significant cytotoxicity of SE-F and polyanions at the concentrations used in the present study.

<p>(<b>A</b>) Cytotoxicity of SE-F to different target cells. Seminal fluids (1∶500) and seminal pellet (1∶200) were incubated with TZM-bl cells or MT-2 cells respectively. After 48-h culture, cytotoxicity was determined by the XTT cell viability assay. The results were expressed as the mean of three different experiments. (<b>B</b>) Cytotoxicity of polyanions to different target cells. Various polyanions (50 µg/ml) were incubated with TZM-bl cells or MT-2 cells respectively. After 48-h culture, cytotoxicity was determined by the XTT cell viability assay. The results were expressed as the mean of three different experiments.</p