International Journal of Molecular Sciences

Salt stress is one of the main abiotic stresses that restrict crop production. Melatonin (MT), a signal molecule widely present in plants, plays an important role in regulating abiotic stress response. In this study, celery seedlings were used as experimental materials, and the control, salt stress, and exogenous MT treatment groups under salt stress were set up. Through phenotypic, physiological index determination, transcriptome sequencing, and expression analysis, the alleviation effects of MT on salt stress were comprehensively investigated. The results showed that exogenous MT treatment significantly reduced seedling growth inhibition caused by salt stress. Physiological measurements showed that MT significantly reduced malondialdehyde content, increased the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), promoted the accumulation of free proline and soluble protein, and increased photosynthetic parameters such as chlorophyll, ΦPSII, Fv/Fm, and ETR. Transcriptome analysis showed that MT regulates the expression of several genes associated with carbon metabolism, including β-amylase gene (AgBAM), sucrose-degrading enzyme genes (AgSUS, AgINV), and glucose synthesis-related genes (AgAG, AgEGLC, AgBGLU). The results of qRT-PCR verification were highly consistent with the transcriptome sequencing data, revealing that MT synergistically regulates starch and sucrose metabolic pathways, and effectively alleviates the damage of celery seedlings under salt stress at the molecular level. In summary, exogenous MT significantly improved the salt tolerance of celery by enhancing antioxidant capacity, maintaining photosynthetic function, promoting the accumulation of osmotic adjustment substances, and synergistically regulating carbon metabolism-related pathways. The concentration of 200 μM was identified as optimal, based on its most pronounced alleviating effects across the physiological parameters measured. This study provides an important theoretical basis for utilizing MT to enhance plant salt resistance.

Cutaneous leishmaniasis (CL) is a neglected tropical disease for which current chemotherapeutic options are limited by systemic toxicity (such as hepato-nephrotoxicity, arrhythmia, nausea, vomiting) and difficult administration regimens. Pentamidine (PTM), although effective, exhibits severe dose-limiting adverse effects. Polymeric micelles based on Pluronic^® F127 (F127) offer an attractive strategy to improve PTM delivery by enhancing solubility, reducing cytotoxicity, and enabling controlled release. Here, we developed PTM-loaded F127 polymeric micelles and performed a multidisciplinary evaluation combining physicochemical characterization, in vitro biological assays, and gene expression profiling. Dynamic light scattering, UV–visible absorption, fluorescence spectroscopy, and NMR confirmed micelle formation, PTM–polymer interactions, and temperature-dependent assembly. PTM-loaded micelles exhibited biorelevant nanoscale dimensions and preserved stability under physiological conditions. Biological assays demonstrated that F127 micelles markedly reduced PTM cytotoxicity in RAW264.7 macrophages while maintaining potent antileishmanial activity against Leishmania major promastigotes. RT-qPCR analysis revealed modulation of key pathways involved in redox homeostasis, oxidative stress, calcium regulation, apoptosis-like responses, and drug resistance, suggesting that micellar encapsulation influences both PTM bioavailability and parasite stress responses. Overall, PTM-loaded F127 micelles significantly improved the therapeutic index of PTM in vitro. These findings support the potential of F127 polymeric micelles as a promising nanocarrier platform for safer and more effective CL therapy.

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