The influence of histamine and quercetin, as well as their combined effect on the content of histamine in whole blood, the content of the superoxide anion radical, sialic acids, sulfhydryl groups, the activity of catalase, glutathione peroxidase, and glutathione transferase in rat erythrocytes was studied. It was established that quercetin at a concentration of 0.1 mM causes an increase in the content of histamine in the whole blood of rats, while all other studied concentrations cause a significant decrease in the content of biogenic amine. Adding histamine to whole blood at a concentration of 1 μM leads to a decrease in the content of endogenous histamine in the blood, while at a concentration of 10 μM, it causes an increase in the content of this biogenic amine. The combined effect of exogenous histamine and quercetin mainly leads to an increase in the amount of endogenous histamine in the whole blood of rats. In rat erythrocytes, quercetin causes the generation of the superoxide anion radical. An increase in the superoxide anion radical content occurs under the influence of histamine at a concentration of 0.1; 1 and 10 μM, while under the action of biogenic amine 0.01 μM, the amount of the studied product decreases. The combined effect of histamine and quercetin intensifies the formation of superoxide anion radical in erythrocytes, in addition to the effect of flavonoid in therapeutic concentration. Adding quercetin and histamine to whole blood causes an increase in the content of sialic acids. Such an effect was also found under the combined action of histamine at a concentration of 0.01 µM and quercetin at a concentration of 0.1; 0.5; 3; 5 mM. The combined effect of histamine at a concentration of 10 µM and quercetin at a concentration of 5 mM leads to a decrease in the content of sialic acids in erythrocytes. Addition of quercetin to whole blood causes an increase in the content of sulfhydryl groups, except for a concentration of 5 mM, at which the content of this indicator decreases. Histamine in a concentration of 0.01; 0.1 μM leads to an increase in the content of SH-groups, and at a concentration of 1 μM – to a decrease. Histamine against the background of exposure to quercetin leads to an increase in the content of sulfhydryl groups. The degree of influence of histamine and quercetin, as well as their combined effect, is the same on the content of endogenous histamine in the blood, sialic acids, sulfhydryl groups in erythrocytes. The independent effect of histamine and quercetin causes a weak effect on the indicated indicators of blood and erythrocytes. The combined effect of histamine and quercetin on the content of the studied indicators has a more pronounced effect. The most significant effect of the combined effect of histamine and quercetin was found on the content of the superoxide anion radical and sialic acids. Quercetin in a concentration of 0.1; 3; 5 mM leads to a decrease in catalase activity, while the studied flavonoid, with a concentration of 0.3; 1 mM, leads to an increase in the activity of the studied enzyme. Histamine at a concentration of 0.1 and 10 µM activates catalase, while biogenic amine (at a concentration of 0.01 and 1 µM) reduces the activity of the enzyme. The combined action of histamine and quercetin leads to an increase in the activity of catalase in hemolysates of erythrocytes of rats. Quercetin only at a concentration of 5 mM, histamine at a concentration of 0.1; 1; 10 μM enhances the activity of glutathione peroxidase. Simultaneous addition to the blood of histamine at a concentration of 10 μM and quercetin at a concentration of 3 and 5 mM, as well as the combined effect of histamine at a concentration of 0.01 μM and quercetin at a concentration of 0.1; 0.5; 3; 5 mM results in the intensification of glutathione peroxidase. Quercetin at a concentration of 0.1 and 0.3 mM does not change the activity of glutathione-S-transferase, while the studied flavonoid (at a concentration of 0.5; 1; 3; 5 mM) causes a significant increase in the activity of the studied enzyme. Histamine in a concentration of 0.01; 0.1; 1 and 10 μM significantly dose-dependently activate glutathione-S-transferase. The combined action of histamine, at a concentration of 10 µM, and quercetin, at a concentration of 0.1; 0.5; 3; 5 mM, leads to a decrease in enzyme activity in rat erythrocyte hemolysates compared to samples to which only histamine was added, but glutathione-S-transferase values did not reach control limits. Compared to the control, the activity of glutathione-S-transferase increases under the simultaneous action of histamine and quercetin. Simultaneous exposure to histamine at a concentration of 0.01 µM and quercetin causes a significant increase in the activity of glutathione-S-transferase. Histamine has a significant effect on catalase activity in rat erythrocytes, while the combined administration of quercetin and histamine into the blood has a powerful effect on the work of glutathione peroxidase and glutathione-S-transferase.
