## 3 Results and Discussion
### Influence of Temperature on the Resultant Effect of the Mixture's Antioxidant Activity
Undoubtedly, the temperature also affects the kinetics of the radical neutralization reaction by the antioxidant. It should be noted here that the measurements of antioxidant properties were carried out in the 60 th minute of the reaction, i.e., after a certain time, not necessarily sufficient for the reaction to reach a steady state. Additionally, the increase in temperature affects the dissociation of the antioxidant, which is necessary for the neutralization reaction of the ABTS radical cation [24]. Moreover, under the influence of temperature, the structure of the solvent may change (breakdown of clusters in the form of which methanol is present), which may facilitate the transfer of the electron and/or hydrogen from the antioxidant to the radical, thus resulting in a faster reaction [25; 26]. In light of the presented data, it seems more important to compare the position and course of the curves obtained for binary mixtures--experimental and computational. These curves do not overlap; the theoretical curve is above the experimental curve, which indicates the antagonistic antioxidant effect of the mixture containing chlorogenic acid and kaempfer. There are not many reports in the literature about the antagonistic effects of compounds in the mixture. For example, in [27] it was shown that the co-occurrence of alkaloids and saponins significantly reduces the antioxidant activity of the quinine tree (_Rauvolfiaacaffra_ sond) extracts (activity of alkaloids alone \(=63\%\); activity of alkaloids with saponins \(=15\%\)). A similar effect was described in [28] for mixtures of \(\beta\)-carotene with flavonoids (daidzein, baicalein) or with green tea polyphenols ((\(-\))-epicatechin (EC), (\(-\))-epigallocatechin (EGC), (\(-\))-epicatechingallate (ECG) and (\(-\))-epigallocatechingallate (EGCG)). The last of the cited works is significant in that it confirms the results presented in this paper. It was shown that although \(\alpha\)-tocopherol with caffeic acid has a synergistic effect, its combination with chlorogenic acid shows antagonism. According to the results presented in this study in Figure 1, this effect is observed regardless of the measurement temperature used. This conclusion is also confirmed by the data in Table 2--\(F>Fcrit\) at \(p<0.05\) are obtained in all tested systems. Assuming that the size of the \(F\) value is an exponent of the size of the antagonistic effect, it can be stated that the greatest antagonism is observed at 15 and 35 \({}^{\circ}\)C (\(F\) values for these temperatures are the highest). Moreover, by comparing the \(F\) value with the change in the concentration of chlorogenic acid, it is possible to observe a temperature-independent increase in the \(F\) value (increase in the antagonistic effect) with an increase in the concentration of chlorogenic acid. At room temperature, for the two volume ratios, i.e., 20/80 and 50/50, the changes are the smallest because the \(F\) values only slightly exceed the \(Fcrit\) value. It is difficult to unambiguously explain the observed antagonistic effect, because it is not only the result of the temperature effect on the individual components of the measurement system, but it may also be the effect of the interaction of the components (antioxidants) with each other. According to the literature, the antagonistic antioxidant effect may be the result of a weaker antioxidant being rebuilt by a stronger one [7]. However, in light of the presented results, the validity of this hypothesis in the case of the kaempfer-chlorogenic acid mixture is questionable. According to the data in Figure 1B (see blue and red curves), kaempfer is a slightly stronger antioxidant than chlorogenic acid. Therefore, it would be expected that with an increase in the amount of kaempfer and not chlorogenic acid, an increase in the antagonistic effect of antioxidants in the mixture would be observed.