Estimation of blood ergothioneine by determination of brominelabile sulfur.

Behre and Benedict (2) developed a procedure for the determination of ergothioneine, based upon the separation of this substance from uric acid, followed by estimation of the ergothioneine by its reaction with a phosphotungstic acid reagent. In discussing the inadequacies of this method and its modifications, Behre in 1932 (3) stated that “no great, reliance can be placed on the figures so far obtained.” Hunter (4) described a method based upon the reaction between diazotized sulfanilic acid and ergothioneine under conditions designed to minimize coupling with other blood constituents. This procedure also proved unsatisfactory (5-8) and was later modified (9) so that it now appears to be considerably more reliable. It was implied, however, that tyrosine and histidine react to some extent in this procedure (9) and it has been suggested that uric acid may affect the test adversely (7, 9). Latner (7) has also reported a diazo procedure for determining blood ergothioneine, but the details of this method have not as yet been published.