The Collaborative International Dictionary of English v.0.48:

Leucomaine \Leu*co"ma*ine\ (l[-u]*k[=o]"m[.a]*[i^]n or -[=e]n),
   n. [Leuco- + -maine, as in ptomaine.] (Physiol. Chem.)
   An animal base or alkaloid, appearing in the tissue during
   life; hence, a vital alkaloid, as distinguished from a
   ptomaine or cadaveric poison.
   [1913 Webster]