(2S,2’S,3R,3’R)-2,2′-((3R,8R)-1,6-bis((2-formimidamidoethyl)thio)-5,10-dioxo-2,3,5,7,8,10-hexahydrodipyrrolo[1,2-a:1′,2′-d]pyrazine-3,8-diyl)bis(3-hydroxybutanoicacid)