Novel phenanthrene derivatives represented by the general formula (1), ##STR1## wherein the group of the formula ##STR2## is a group of the formula ##STR3## (wherein R.sup.1 is a hydrogen atom or a lower alkyl group), a group of the formula ##STR4## (wherein R.sup.2 is a hydrogen atom or a lower alkanoyl group) or a group of the formula ##STR5## (wherein R.sup.2 is the same as defined above), and salts thereof, and other compounds derived therefrom and salts thereof; processes for preparing the same; and interleukin-1 (IL-1) inhibitors containing the abovementioned novel phenanthrene derivatives as to the active ingredient(s).