Tacrolimus anhydrous 8-epimer is a new l-pipecolic acid macrolide lactone, an important immunosuppressive drug that blocks T cell proliferation in vitro by inhibiting the generation of several lymphokines, especially IL-2.

[1] Skytte D M ,  Frydenvang K ,  Hansen L , et al. Synthesis and Characterization of an Epimer of Tacrolimus, an Immunosuppressive Drug[J]. Journal of Natural Products, 2010, 73(4):776-9.