Leishmaniasis is a neglected tropical disease caused by Leishmania sp. The therapeutic arsenal is reduced and limited. In this context, acridine derivatives present themselves as promising leishmanicidal compounds. This paper involved synthesizing and evaluating the antileishmanial and immunomodulatory potential of spiro-acridine derivatives. Six spiro-acridine derivatives were obtained through nucleophilic substitution reactions between the acetohydrazide/acetamide intermediates and 9-carbaldehydeacridine, followed by spontaneous cyclization. IR, NMR, and HRMS confirmed the structures. These were analyzed in vitro against L. infantum and L. amazonensis to determine anti-promastigote, anti-amastigote, and cytotoxicity effects. Immunomodulatory activity was evaluated using CBA, DCF-DA, and DAF-FM diacetate. In silico evaluation included molecular docking and dynamics. The spiro-acridines showed a wide range of anti-promastigote activities (IC₅₀ = 0.73–234.95 µM) and non-toxicity to red blood cells. AMTAC-02 and ACMD-03 demonstrated satisfactory anti-amastigote effect (IC₅₀ = 10.47–13.50 µM), low toxicity to macrophages (CC₅₀ = 27.22–569.50 µM), and cytokine and reactive species modulation. Molecular docking proposed cysteine protease B of L. amazonensis as a target, and molecular dynamics analysis highlighted the complex’s stability using RMSD, R_g, SASA, DCCM, PCA, and MM-PBSA (ΔG = −65.225 kJ/mol). Furthermore, QM-MM calculation provided the best energy for ACMD-03 (−199.30 au). Hence, AMTAC-02 and ACMD-03 demonstrated antileishmanial potential, making them promising entities for the development of leishmanicidal drug candidates.

Ibrutinib (IBR) is a tyrosine kinase inhibitor investigated for treating solid and non-solid tumors. Considering the advantages that a topical application of IBR could generate in terms of dose reduction and side effects in skin cancer treatment, this paper presents a simple and selective HPLC method for determining IBR concentration in in vitro skin permeation studies to support the development of topical formulations. The method uses a reversed-phase C₁₈ column and a mobile phase composed of acetonitrile and 0.01 mol/L phosphoric acid at pH 3.5 (35:65 v/v), flowing at 1.0 mL/min. The oven temperature was set at 35 °C, the injection volume was 20 μL, and UV drug detection was performed at 259 nm. The validation procedure certified that this method was selective for IBR determination even when extracted from human or porcine skin matrices. The method was linear over a range of 0.2 to 15.0 μg/mL, precise, robust, and accurate, with recovery rates from the skin layers higher than 89.5 ± 5.9% for the porcine skin and higher than 92.0 ± 0.2% for the human skin. The limits of detection and quantification were 0.01 and 0.02 μg/mL, respectively. The method showed, therefore, to be adequate for use in further skin permeation studies employing IBR topical formulations.

Background/Objectives: Ibrutinib (IBR) is a tyrosine kinase inhibitor under investigation in preclinical and clinical settings as an alternative treatment for melanoma. Nevertheless, the limited oral bioavailability of IBR and the need for high doses of the drug to kill melanoma cells are major drawbacks for this purpose. Considering that melanoma is restricted to the skin at early stages, the topical application of IBR might constitute an effective and safer administration route. In this study, we determined IBR’s toxicity and dermatokinetics using human primary cells and human organotypic skin explant cultures (hOSECs). Methods: After demonstrating that human primary fibroblasts and keratinocytes present IBR target genes, the cytotoxicity of the drug was determined using the MTT and annexin V/PI staining assays. IBR toxicity in the skin was assessed using the TTC assay, and the irritation potential was established using histological assessment. Finally, IBR cutaneous permeation was assessed ex vivo to determine the drug dermatokinetics. Results: Our findings reveal that IBR exerts dose-dependent toxicity towards skin cells, presenting an IC₅₀ in the same range as melanoma cells. The topical application of the drug successfully reduced irritation and toxicity in the skin, and the drug was shown to successfully permeate the stratum corneum and reach the viable skin layers in therapeutic concentrations. Conclusions: Overall, our data encourage the topical application of IBR to treat melanoma, paving the way for future studies in this theme.