A Multifunctional Oxovanadium(V) Schiff Base Complex: Integrated Pyridoxine Sensing and Anticancer and Antimicrobial...

The multifunctional properties of a new oxovanadium(V) complex [VO(L) (5-Cl-8-HQ)] containing a Schiff base derived from L-arginine and salicylaldehyde and 5-chloroquinolin-8-ol, were investigated in this study. The complex was characterized using elemental analysis, cyclic voltammetry, powder X-ray diffraction, as well as FTIR, UV-Vis, and ¹H NMR spectroscopies. The electrochemical function of the complex as a sensor for pyridoxine detection showed a quasireversible behavior with an electrochemical rate constant of k _e  = 0.133 s^-1 in the linear range of detection of 1.0 × 10^-8 to 1.0 × 10^-4 mol·L^-1, with a limit of detection of 4.24 × 10^-8 mol·L^-1. The complex also exhibited good activity as a potential anticancer agent in regard to the MDA-MB-231 breast cancer cell line, with IC₅₀ = 35.09 ± 0.03 μg/mL with a steep hill slope of 2.575 in the dose-response curve, suggesting a sensitive cellular response to the complex, indicating promising anticancer potential. UV-Vis spectroscopy remains the method of choice for stability studies conducted under physiological conditions. The results showed a progressive complex breakdown in the cell culture medium at 37°C over 96 h, implying that its biological activity could be a mixture of the degradation products of the complex. The complex also showed antimicrobial effects at concentrations of 10 and 20 ppm against Staphylococcus aureus, Enterococcus faecalis, and Aspergillus niger, with the diameter of the inhibition zone (IZ) increasing with increasing complex concentration. The combination of these electrochemical sensing properties with the dual therapeutic potential as an anticancer and antimicrobial agent places this class of vanadium complexes in a versatile position for further development in both analytical and medicinal fields.