Uptake and Protective Effects of Ergothioneine in Human Endothelial Cells

Abstract

Ergothioneine is a thiourea derivative of histidine found in food, especially mushrooms. Experiments in cell-free systems and chemical assays identified this compound as a powerful antioxidant. Experiments were designed to test the ability of endothelial cells to take up ergothioneine and hence benefit from protection against oxidative stress. Reverse-transcription polymerase chain reaction and Western blotting demonstrated transcription and translation of an ergothioneine transporter in human brain microvascular endothelial cells (HBMECs). Uptake of [3 H]ergothioneine occurred by the organic cation transporter novel type-1 (OCTN-1), was sodium-dependent, and was reduced when expression of OCTN-1 was silenced by small interfering RNA (siRNA). The effect of ergothioneine on the production of reactive oxygen species (ROS) in HBMECs was measured using dichlorodihydrofluorescein and lucigenin, and the effect on cell viability was studied using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. ROS production and cell death induced by pyrogallol, xanthine oxidase plus xanthine, and high glucose were suppressed by ergothioneine. The antioxidant and cytoprotective effects of ergothioneine were abolished when OCTN-1 was silenced using siRNA. The expression of NADPH oxidase 1 was decreased, and those of glutathione reductase, catalase, and superoxide dismutase enhanced by the compound. In isolated rat basilar arteries, ergothioneine attenuated the reduction in acetylcholine-induced relaxation caused by pyrogallol, xanthine oxidase plus xanthine, or incubation in high glucose. Chronic treatment with the compound improved the response to acetylcholine in arteries of rats with streptozotocin-induced diabetes. In summary, ergothioneine is taken up by endothelial cells via OCTN-1, where the compound then protects against oxidative stress, curtailing endothelial dysfunction.

The biology of ergothioneine, an antioxidant nutraceutical

“…The distribution of solute transporters between tissues in differentiated organisms is particularly heterogeneous (119) , and it is to be expected that both SLC22A4 and ERG might also be distributed heterogeneously as well. This is indeed the case, their distribution being especially high in tissues that are considered to have the potential for oxidative stress (4) , such as erythrocytes (120)(121)(122)(123)(124)(125)(126)(127)(128)(129) , bone marrow (130) , liver and kidney (85,131) , seminal fluid (132,133) and the lens and cornea of the eyes (134) . It may also be accumulated in the CNS (135,136) .…”

“…In evaluating the antioxidant potency of ERG or anything else, it is molecules such as these that are normally assessed. Although the literature is somewhat scattered and heterogeneous, it seems clear that as well as hydroxyl radicals (228)(229)(230)(231)(232) , ERG can also react with and detoxify, or prevent the formation of, singlet oxygen (233)(234)(235)(236)(237)(238)(239)(240)(241)(242) , ozone (243) , superoxide (231,241,(244)(245)(246) , peroxide (32,124,247,248) , hypochlorite (32,232,249) and peroxynitrite (224,231,250,251) . Consequently, it is a potent antioxidant.…”

“…At a high level, ERG is seen as an excellent cytoprotectant against all kinds of cellular insults (3,4,6,124) . We split some of the more detailed analyses into subdivisions in the following few sections.…”

“…It is protective against the oxidation of various kinds of molecule (251,474) , including astaxanthin (475) , and accumulates in a guinea-pig model of non-alcoholic fatty liver disease (476) , massively so in mouse models of myocardial infarction and heart failure (477) , and in a rat model of optic nerve crush (478) . It serves to resist H 2 O 2 -induced cell death (479) , pyrogallolinduced toxicity (124) , cisplatin- (480) or oxaliplatin-induced (481) toxicity, glucose-induced senescence (246,482) , as well as lipopolysaccharide-induced inflammation (483) . In particular, it is protective against ischaemia-reperfusion injury (484)(485)(486) , and may have uses in prolonging the lifetime of stored blood (487) .…”

A Safety Evaluation of a Nature-Identicall-Ergothioneine in Sprague Dawley Rats

“…10,12 The ability to accumulate L-ergothioneine in these tissues has been reported to confer increased antioxidant potential, the reduction of which can lead to mitochondrial DNA damage, lipid peroxidation, and protein oxidation. [12][13][14][15][16] Case-control and in vitro studies of inflammatory disease, such as Crohn's, ulcerative colitis and diabetes, have reported an association with polymorphism in the SLC22A4 gene responsible for L-ergothioneine production and expression. [17][18][19][20][21] Beneficial physiologic properties of L-ergothioneine include its rapid clearance from the circulation into retained tissues with minimal metabolism and high stability (low redox potential), long half-life (approximately 30 days), and its reduced tendency to auto-oxidize or generate free radicals from peroxide and Fe 2þ at physiologic pH, apart from that of glutathione.…”