Interactions of Extracts from Selected Plant Materials Supporting the Treatment of Alzheimer’s Disease with Free Radicals—EPR and UV-Vis Studies

<b>Background/objectives</b>: Interactions of infusions of <i>Ginkgo biloba</i>, ginseng, Yerba Mate, and green tea, with free radicals, were examined. The aim of these studies was to determine quenching of free radicals by the extracts from the selected plant raw materials that are useful in the treatment of Alzheimer's disease. <b>Methods</b>: The interactions were tested by an X-band (9.3 GHz) EPR spectroscopy and UV-Vis spectrophotometry. The model DPPH free radicals were used. The magnitude and changes with time of EPR and UV-Vis spectra of DPPH by the tested extracts were measured. <b>Results</b>: EPR and UV-Vis lines of DPPH free radicals decrease with increasing time of interactions of the extracts with DPPH, and after reaching the minimum value, it does not change with time. Ginseng infusion quenched free radicals the least. <i>Ginkgo biloba</i> extract quenches free radicals a little stronger than ginseng extract. Taking into account the tested extracts, <i>Ginkgo biloba</i> and ginseng extracts interact with free radicals less effectively compared to extracts of Yerba mate and green tea. <i>Ginkgo biloba</i> and ginseng extracts quench free radicals weaker than Yerba Mate and green tea extracts. <b>Conclusions</b>: Yerba Mate extract definitely had the strongest antioxidant properties. This extract quenches free radicals most effectively, what can be useful in the case of Alzheimer's disease. Given its strong antioxidant properties, green tea extract can also be particularly recommended in the case of Alzheimer's disease.