## 3 Results and Discussion  
Figures 1-4 show the antioxidant properties, expressed as percent inhibition, determined for the one-component systems containing either chlorogenic acid or kaempfer and for the systems that are binary mixtures thereof. The studies used methanol or ethanol solutions of the tested antioxidants at a concentration of 0.06 mg/mL, which were mixed with each other in different volume ratios to prepare their binary mixtures (20/80; 50/50; 80/20 \(v/v\)--see Table 1). Each of the presented graphs was created on the basis of data obtained in various measurement systems, which were differentiated due to the temperature (Figure 1), solvent used (Figure 2) or the presence of water (Figure 3), or metal ions or hydrogen ions (Figure 4). In each of the figures presented, the red curve shows the changes in antioxidant activity in systems containing a variable amount of chlorogenic acid, while the blue curve reflects the antioxidant properties observed in the systems with different kaempfer content. Additionally, each figure contains two curves--the purple one, which is called \"the experimental curve\", and the green one, which is the so-called \"calculated curve\". The former shows the antioxidant activity changes for the experimental systems containing different volumes of the test compounds in the binary mixtures and the latter presents the calculated value of the antioxidant activity in the mixtures. The calculated curve was constructed based on the summation of antioxidant activity obtained for individual antioxidants in one-component systems containing the same amount of the ingredient as in the two-component mixture. For clarification, for a mixture containing 20 \(\upmu\)L of chlorogenic acid and 80 \(\upmu\)L of kaempfer, the calculated percentage of inhibition is 46.12 as shown in point \"d\" in Figure 1A. This value was obtained after adding up the % of inhibition determined in the systems containing: 20 \(\upmu\)L of chlorogenic acid solution, i.e., 12.07% (value in point \"a\" on the graph, single-component system marked No. 1 in Table 1) and 80 \(\upmu\)L of kaempfer solution, i.e., 34.05% (value in point \"b\" on the graph, single-component system marked No. 6 in Table 1). Point \"c\" is the experimental value (le), the actual value obtained for a mixture containing 20 \(\upmu\)L of chlorogenic acid and 80 \(\upmu\)L of kaempfer. The difference between the experimental value, the value in point \"c\" (le), and the theoretical value, the value in point \"d\" (lc), indicates the observed, resultant effect of the antioxidant effect of the mixture--if it is negative, we are dealing with antagonism, and if it is a positive value, we are dealing with synergism. It is worth noting at this point that in the plots, the antioxidant amounts in the measuring system are expressed as the volume of its solution of a given concentration in a 100 \(\upmu\)L sample introduced to the system. The solution volume of the chlorogenic acid in the pair, is shown on the lower \(X\) axis. The volume of the kaempfer is shown on the upper \(X\) axis. Values on the axis titled \"volume for kaempfer\" (top axis) should be read from right to left. Figure 1: The antioxidant activity changes assessed by the ABTS method for the systems containing different volumes of chlorogenic acid solution (red line with squares), kaempfer solution (blue line with diamonds), and their binary mixtures (violet line with “x”). The green line with triangles corresponds to the expected activity values for the tested pairs of compounds. The experimental values are the mean values for \(n=5\). The experiments were carried out at three different temperatures, i.e., 15 \({}^{\circ}\)C (**A**), 25 \({}^{\circ}\)C (**B**) and 35 \({}^{\circ}\)C (**C**). Figure 2: The antioxidant activity changes assessed by the ABTS method for the systems containing different volumes of methanolic (**A**) and ethanolic (**B**) solutions of: chlorogenic acid (red line with squares), kaempfer (blue line with diamonds), and their binary mixtures (violet line with “x”).