Preliminary in vitro evaluation of the immunomodulatory, schistosomicidal, antibacterial, antifungal, and antitumor activities of naphthyl-thiazole compounds.

The search for new compounds with multiple therapeutic actions is crucial to address public health challenges such as microbial and parasitic resistance, as well as cancer. In this context, this study evaluated the in vitro immunomodulatory, schistosomicidal, antimicrobial, and antitumor activities of 13 thiosemicarbazones (1a-m) and 16 thiazoles (2a-p). All compounds exhibited low cytotoxicity in murine splenocytes, maintaining cell viability above 95%. They significantly modulated markers of pro- and anti-inflammatory immune responses, increasing levels of IL-2, IL-4, IL-10, IFN-γ, mitochondrial and cytosolic reactive oxygen species (ROS), mitochondrial membrane potential, intracellular calcium concentration, and increasing CD4⁺ and CD8⁺ lymphocyte populations, while reducing nitric oxide production. Against Schistosoma mansoni, thiazoles demonstrated greater activity than thiosemicarbazones, particularly compound 2k (IC₅₀: 31.4µM for juveniles, 30.1µM for adults). In antimicrobial assays, moderate activity was observed, with MIC values ranging from 16 to 128µg/mL against bacteria and fungi. In antitumor tests, thiazole derivatives demonstrated greater potency and selectivity than thiosemicarbazones (IC₅₀: 0.80-0.92µM vs. 1.11-1.30µM), particularly compounds 2g and 2f. These findings confirm the multi-target therapeutic potential of these compounds, supporting their candidacy for the development of drugs targeting infectious diseases and cancer.