Fe3O4/Stixis scandens extract nanosystems for inhibiting African swine fever virus

African swine fever virus (ASFV) is a highly contagious and lethal pathogen that poses a serious threat to pig production and leads to significant economic losses. This study aimed to develop nanosystems based on iron oxide (Fe₃O₄) using different extracts (in different solvents) of Stixis scandens leaves and to evaluate their antiviral activity against ASFV. The synthesized nanosystems were characterized using various techniques, including Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV–Vis), field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), and thermogravimetric analysis (TGA). The total polyphenol (TP) and total alkaloid (TA) content of the extracts was quantified, as well as the corresponding loading and release profiles from the nanosystems. The Fe₃O₄ nanoparticles exhibited a uniform size distribution (10–15 nm), high colloidal stability (zeta potential ranging from –106.0 mV to –65.2 mV), superparamagnetic behavior, and efficient heat generation under an alternating magnetic field. Release studies showed that TA was released more slowly than TP under both passive and magnetically induced conditions, and that increased temperature improved both release kinetics and antiviral efficacy. Among the formulations tested, F2, which consitsted of extract E2 (with the highest TA content) and the highest extract loading (15.3%), exhibited the strongest antiviral activity. This formulation completely inhibited ASFV replication at a concentration of 250 ppm and an incubation temperature of 45 °C and achieved a 4.5 log10 reduction in viral titer. These results emphasize the potential of Fe₃O₄ plant extract nanosystems as a novel approach for ASFV inhibition in veterinary medicine.