Parkinson's disease and dementia with Lewy bodies are associated with abnormal neuronal aggregation of α-synuclein. However, the mechanisms of aggregation and their relationship to disease are poorly understood. We developed anin vivomultiphoton imaging paradigm to study α-synuclein aggregation in mouse cortex with subcellular resolution. We used a green fluorescent protein-tagged human α-synuclein mouse line that has moderate overexpression levels mimicking human disease. Fluorescence recovery after photobleaching (FRAP) of labeled protein demonstrated that somatic α-synuclein existed primarily in an unbound, soluble pool. In contrast, α-synuclein in presynaptic terminals was in at least three different pools: (1) as unbound, soluble protein; (2) bound to presynaptic vesicles; and (3) as microaggregates. Serial imaging of microaggregates over 1 week demonstrated a heterogeneous population with differing α-synuclein exchange rates. The microaggregate species were resistant to proteinase K, phosphorylated at serine-129, oxidized, and associated with a decrease in the presynaptic vesicle protein synapsin and glutamate immunogold labeling. Multiphoton FRAP provided the specific binding constants for α-synuclein's binding to synaptic vesicles and its effective diffusion coefficient in the soma and axon, setting the stage for future studies targeting synuclein modifications and their effects. Ourin vivoresults suggest that, under moderate overexpression conditions, α-synuclein aggregates are selectively found in presynaptic terminals.

The polyamine pathway in Leishmania parasites has emerged as a promising target for therapeutic intervention, yet the functions of polyamines in parasites remain largely unexplored. Ornithine decarboxylase (ODC) and spermidine synthase (SPDSYN) catalyze the sequential conversion of ornithine to putrescine and spermidine. We previously found that Leishmania donovani Δodc and Δspdsyn mutants exhibit markedly reduced growth in vitro and diminished infectivity in mice, with the effect being most pronounced in putrescine-depleted Δodc mutants. Here, we report that, in polyamine-free media, ∆odc mutants arrested proliferation and replication, while ∆spdsyn mutants showed a slow growth and replication phenotype. Starved ∆odc parasites also exhibited a marked reduction in metabolism, which was not observed in the starved ∆spdsyn cells. In contrast, both mutants displayed mitochondrial membrane hyperpolarization. Hallmarks of apoptosis, specifically DNA fragmentation and membrane modifications, were observed in Δodc mutants incubated in polyamine-free media. These results show that putrescine depletion had an immediate detrimental effect on cell growth, replication, and mitochondrial metabolism and caused an apoptosis-like death phenotype. Our findings establish ODC as the most promising therapeutic target within the polyamine biosynthetic pathway for treating leishmaniasis.

χ-Conotoxins are known for their ability to selectively inhibit norepinephrine transporters, an ability that makes them potential leads for treating various neurological disorders, including neuropathic pain. PnID, a peptide isolated from the venom of Conus pennaceus, shares high sequence homology with previously characterized χ-conotoxins. Whereas previously reported χ-conotoxins seem to only have a single native disulfide bonding pattern, PnID has three native isomers due to the formation of different disulfide bond patterns during its maturation in the venom duct. In this study, the disulfide connectivity and three-dimensional structure of these disulfide isomers were explored using regioselective synthesis, chromatographic coelution, and solution-state nuclear magnetic resonance spectroscopy. Of the native isomers, only the isomer with a ribbon disulfide configuration showed pharmacological activity similar to other χ-conotoxins. This isomer inhibited the rat norepinephrine transporter (IC₅₀ = 10 ± 2 µM) and has the most structural similarity to previously characterized χ-conotoxins. In contrast, the globular isoform of PnID showed more than ten times less activity against this transporter and the beaded isoform did not display any measurable biological activity. This study is the first report of the pharmacological and structural characterization of an χ-conotoxin from a species other than Conus marmoreus and is the first report of the existence of natively-formed conotoxin isomers.

The genus Leishmania consists of over 20 different species causing a spectrum of disease symptoms categorized as cutaneous, mucocutaneous, or visceral leishmaniasis. No vaccine is available in humans, and current drug regimens suffer from low efficacy, associated toxicities, and are increasingly becoming side-lined by drug resistance. Because of this, the development of new therapeutics is desperately needed. Recent years, the therapeutic use of nanotechnology has increased exponentially. The biogenic synthesis of these nanostructures creates particles similar to those chemically synthesized but are often more environmentally safe, cost-effective, and allow for increased control over size, shape, and composition. Here, we provided a review of the current publications using the biogenic synthesis of nanoparticles particularly focusing on those used in the treatment of leishmaniasis published from January 1, 2010, to April 30, 2025. The documents were analyzed by applying criteria such as nanometal type, source of green synthesis (plant or microorganism), nanoparticles size, Leishmania species (sp.) and stage (promastigote or amastigote), cytotoxicity, and in vivo studies. A total of 50 articles were analyzed. Among biogenic nanoparticles (NPs), silver NPs were the most extensively studied (15 studies), while Leishmania tropica (L. tropica) was the most frequently investigated sp. Plant material was the most sources starting material for green synthesis. Produced NPs’ size varied between 2 and 500 nm. Regarding the effect of NPs on Leishmania parasites, most were done in vitro, and only 5 in vivo studies (10%) reported. Moreover, leishmanicidal effects were reported via oxidative stress, mainly through production of reactive oxygen species and nitrogen radical species. In general, green synthesis produced NPs with smaller sizes, larger surface area to volume ratios, and better internalization by the cells. Thus, green synthesis of NPs could be a promising option to resolve current treatment safety and efficacy concerns while also maintaining accessibility in low- and middle-income countries.