Bioavailability and antioxidant effect of ergothioneine in human blood

Edible mushrooms, such as the white button mushrooms contain several biological compounds including ergothioneine (ET). The main function of ET seems to be to protect cells from oxidative stress. Although humans cannot synthesize ET, the human body does have its own ergothioneine transporter (ETT), which allows cells, for instance red blood cells (RBCs), to take up and store ET. The existence of this transporter suggests that ET might have a physiological importance in humans. The aims of this study were to examine the availability of ET in RBCs and the protective effect of ET on oxidative stress in RBCs. The uptake of ET in RBCs was studied in vitro by treating RBCs with known concentrations of ET (0-100 µM). The amount of ET in the RBCs was determined using high performance liquid chromatography (HPLC). The protective effect of ET was studied by measuring the haemolysis in oxidative stress induced RBCs, which were pre-treated with ET in concentrations ranging from 0-100 µM. In addition, a pilot study was performed where 10,6 mg ET was administered to subjects (n = 6) through a mushroom soup. Before and three hours after consumption, blood samples were collected. The blood samples were analyzed to determine the concentration ET in the RBCs using HPLC and the protective effect of ET was studied the same way as for in vitro. Main findings were that ET was taken up in RBCs after treatment with all ET concentrations, but only after 30 minutes and two hours. Furthermore, RBCs pre-treated with ET had less haemolysis than nontreated RBCs; pre-treatment with 100 µM ET was observed to significantly (p<0,016) decrease haemolysis in comparison with the non-treated RBCs. Consumption of the mushroom soup did not result in increased ET levels in the RBCs, although three out of five subjects had less haemolysis compared to consumption of the placebo soup. However, the beneficial effects after consumption of the mushroom soup cannot be assigned to ET for sure; other unobserved compounds could be involve