Injury-Induced Biosynthesis of Methyl-Branched Polyene Pigments in a White-Rotting Basidiomycete

A stereaceous basidiomycete was investigated with regard to its capacity to produce yellow pigments after physical injury of the mycelium. Two pigments were isolated from mycelial extracts, and their structures were elucidated by ESIMS and one- and two-dimensional NMR methods. The structures were identified as the previously undescribed polyenes (3<i>Z</i>,5<i>E</i>,7<i>E</i>,9<i>E</i>,­11<i>E</i>,13<i>Z</i>,15<i>E</i>,17<i>E</i>)-18-methyl-19-oxoicosa-3,5,7,9,11,13,15,17-octaenoic acid (<b>1</b>) and (3<i>E</i>,5<i>Z</i>,7<i>E</i>,9<i>E</i>,11<i>E</i>,­13<i>E</i>,15<i>Z</i>,17<i>E</i>,19<i>E</i>)-20-methyl-21-oxodocosa-3,5,7,9,11,13,15,17,19-nonaenoic acid (<b>2</b>). Stable-isotope feeding with [1-¹³C]­acetate and l-[methyl-¹³C]­methionine demonstrated a polyketide backbone and that the introduction of the sole methyl branch is most likely <i>S</i>-adenosyl-l-methionine-dependent. Dose-dependent inhibition of <i>Drosophila melanogaster</i> larval development was observed with both polyenes in concentrations between 12.5 and 100 μM. GI₅₀ values for <b>1</b> and <b>2</b> against HUVEC (K-562 cells) were 71.6 and 17.4 μM (15.4 and 1.1 μM), respectively, whereas CC₅₀ values for HeLa cells were virtually identical (44.1 and 45.1 μM)

Structure and Biomedical Applications of Amyloid Oligomer Nanoparticles

Amyloid oligomers are nonfibrillar polypeptide aggregates linked to diseases, such as Alzheimer’s and Parkinson’s. Here we show that these aggregates possess a compact, quasi-crystalline architecture that presents significant nanoscale regularity. The amyloid oligomers are dynamic assemblies and are able to release their individual subunits. The small oligomeric size and spheroid shape confer diffusible characteristics, electrophoretic mobility, and the ability to enter hydrated gel matrices or cells. We finally showed that the amyloid oligomers can be labeled with both fluorescence agents and iron oxide nanoparticles and can target macrophage cells. Oligomer amyloids may provide a new biological nanomaterial for improved targeting, drug release, and medical imaging