▁c oval ent ▁Michael ▁addition . ▁ ▁Site - direct ed ▁spin ▁label ing ▁for ▁E PR ▁or ▁param agnet ic ▁relax ation - en hanced ▁N MR ▁also ▁uses ▁c yst e ine ▁extens ively . ▁ ▁Red uc ing ▁to xic ▁effects ▁of ▁alco hol ▁C yst e ine ▁has ▁been ▁proposed ▁as ▁a ▁prevent ive ▁or ▁ant id ote ▁for ▁some ▁of ▁the ▁negative ▁effects ▁of ▁alco hol , ▁including ▁li ver ▁damage ▁and ▁hang over . ▁It ▁counter act s ▁the ▁poison ous ▁effects ▁of ▁ac etal de hy de . ▁C yst e ine ▁supports ▁the ▁next ▁step ▁in ▁met abol ism , ▁which ▁turns ▁ac etal de hy de ▁into ▁ac etic ▁acid . ▁ ▁In ▁a ▁rat ▁study , ▁test ▁animals ▁received ▁an ▁L D 9 0 ▁do se ▁of ▁ac etal de hy de . ▁Those ▁that ▁received ▁c yst e ine ▁had ▁an ▁ 8 0 % ▁surv ival ▁rate ; ▁when ▁both ▁c yst e ine ▁and ▁th iam ine ▁were ▁admin ister ed , ▁all ▁animals ▁surv ived . ▁ ▁The ▁control ▁group ▁had ▁a ▁ 1 0 % ▁surv ival ▁rate . ▁No ▁direct ▁evidence ▁indicates ▁its ▁effect iveness ▁in ▁humans ▁who ▁consume ▁alco hol ▁at ▁low ▁levels . ▁ ▁N - Ac et yl c yst e ine ▁N - Ac et yl -- c yst e ine ▁is ▁a ▁derivative ▁of ▁c yst e ine ▁where in ▁an ▁ac et yl ▁group ▁is ▁attached ▁to ▁the ▁nit ro gen