176 The Biochemistry of Semen 



oxidizing agents such as ferric chloride or bromine water. These 

 facts suggested that the reducing substance under investigation may 

 be the imidazole base ergothioneine. Further purification led to the 

 isolation from 1300 ml. of boar vesicular secretion of 0-48 g. crystal- 

 line material which was finally identified by analysis of sulphur 

 (140%), nitrogen (18-3%), carbon (471%) and hydrogen (6-6%), 

 and by other chemical means, as pure ergothioneine, C9H15N3O2S. 

 With the isolation of ergothioneine from the boar vesicular secre- 

 tion and boar semen, a rather unsuspected and abundant source 

 of this sulphur-containing base in nature has been discovered. Un- 

 like in blood, however, ergothioneine in the vesicular secretion is an 

 extracellular constituent. Moreover, the concentration of ergothio- 

 neine in this accessory secretion is much higher than in blood. In 

 samples from twenty boars of the Large White and Essex variety, 

 we found from 29 to 256 mg./lOO ml.; the average was 79 mg./lOO 

 ml.; in boar semen itself the concentration is about 15 to 20 mg./lOO 

 ml., but pig urine (boar and sow), and the foetal fluids contain 

 practically no ergothioneine (Mann and Leone, 1953). 



The function of seminal ergothioneine and its behaviour towards 

 sulphydryl-binding substances 



If ergothioneine possesses a specific physiological role in boar 

 semen, this may well be linked, through its reducing sulphydryl 

 groups, with a protective influence on spermatozoa. Boar semen, 

 it must be remembered, differs from that of most other domestic 

 animals by its exceptionally large volume and, at the same time, 

 very low concentration of spermatozoa. Moreover, the period of 

 time required for the completion of ejaculation is much longer in 

 the boar than in other animals. Under storage conditions in vitro, 

 the survival period of ejaculated boar spermatozoa compares on 

 the whole unfavourably with that of ram and bull sperm. 



The results of investigations by Brachet (1944) and MacLeod 

 (1951) have brought into prominence the importance of reduced 

 sulphydryl groups for sperm motility, and, as previously mentioned 

 (p. 58), substances with sulphydryl groups in a reduced form, such 

 as cysteine or reduced glutathione, protect spermatozoa in vitro 

 from the inhibitory action of SH-binding reagents. It is probable 

 that glutathione plays actually a role in vivo since it has been shown 



