Bioactivity of Novel Colchicine, Colchiceine, and 10-Methylthiocolchicine Complexes with Lithium, Sodium, and Potassium Chlorides: Experimental and Theoretical Studies

Complexes of colchicine, colchiceine, and 10-methylthiocolchicine with Li+, Na+, and K+ cations in the form of chlorides were synthesized and then subjected to spectral analysis, DFT theoretical studies, and molecular modeling. The values for water solubility and lipophilicity were also determined using various platforms; both factors are very important for determining the bioavailability of the tested compounds. These compounds were also tested for their fungicidal, herbicidal, insecticidal, and cytotoxic activities. Preliminary in silico studies showed that colchicine, colchiceine, 10-methylthio-colchicine, and their chloride complexes are inactive against selected fungi, weeds, and insects. Colchicine did not show antifungal properties in biological tests and was only active against Aureobasidium pullulans, as were its chloride complexes. The process of complexing colchiceine with metal cations in chloride salts significantly improved the antifungal potency against the selected species A. pullulans and Chaetomium globosum. The highest efficacy of colchiceine complexes was observed only against A. pullulans (MIC = 130 µg/mL) and Ch. globosum (MIC = 65 μg/mL). In contrast to the antifungal activity results, anticancer studies showed that 10-methylthiocolchicine complexes are more active against the SKOV-3 cell line (~IC50 = 2 nM) than colchicine or colchiceine. Molecular-modeling studies confirmed that lithium-coordinated compounds strongly stabilized the active ligand-tubulin complex, which may contribute to the observed cytotoxic activity.