Teratogen metabolism: activation of thalidomide and thalidomide analogues to products that inhibit the attachment of cells to concanavalin A coated plastic surfaces.

Thalidomide metabolites inhibited the attachment of tumor cells to concanavalin A coated polyethylene surfaces. Thalidomide, itself, was non-inhibitory. Thalidomide activation to inhibitory products required hepatic microsomes, an NADPH-generating system, and molecular oxygen. Production of inhibitory metabolites was unaffected by either epoxide hydrolase or 1,2-epoxy-3,3,3-trichloropropane (TCPO), an inhibitor of epoxide hydrolase endogenous to hepatic S9 fraction. Therefore, the attachment inhibitor was probably not an arene oxide. Inhibition was not accompanied by cytotoxicity, as judged by trypan blue exclusion. Although uninduced hepatic microsomes from mice, rats and dogs had similar abilities to activate thalidomide, microsomes from Aroclor 1254 induced rats were relatively inactive in the system. Inhibitory metabolites were generated from the thalidomide analogues EM8 , EM12 , EM16 , EM87 , EM136 , EM255 , E350 , phthalimide, phthalimido-phthalimide, indan, 1- indanone and 1,3- indandione . Glutarimide , glutamic acid and phthalic acid did not activate to inhibitory products.