A novel tetracyclic compound useful as an immuno-suppressant, represented by general formula (I), or a pharmacologically acceptable salt thereof wherein X¹ and X² may be the same or different from each other and each represents hydrogen or lower alkyl, and n represents an integer of 1 to 4.
The present invention relates to novel tetracyclic compounds represented by formula (I) ##STR1## (wherein each of X.sup.1 and X.sup.2 independently represents hydrogen or lower alkyl; n represents an integer of 1 to 4), or a pharmaceutically acceptable salt thereof, which are useful as immunosuppressive agents.