The Collaborative International Dictionary of English v.0.48:

Alkaloid \Al"ka*loid\ ([a^]l"k[.a]*loid), Alkaloidal
\Al`ka*loid"al\ ([a^]l`k[.a]*loid"al), a. [Alkali + -oid: cf. F.
   alcalo["i]de.]
   1. Pertaining to, resembling, or containing, alkali.
      [1913 Webster]

   2. of or pertaining to alkaloids.
      [WordNet 1.5]

WordNet (r) 3.0 (2006):

alkaloidal
    adj 1: pertaining to or consisting of alkaloids