The Collaborative International Dictionary of English v.0.48:

Ligustrin \Li*gus"trin\ (l[-i]*g[u^]s"tr[i^]n), n. (Chem.)
   A bitter principle found in the bark of the privet
   (Ligustrum vulgare), and extracted as a white crystalline
   substance with a warm, bitter taste; -- called also
   ligustron.
   [1913 Webster]