A compound selected from those of the formula I: ##STR1## in which: R.sub.1 represents hydrogen or alkyl having 1 to 3 inclusive carbon atoms,R represents hydrogen, alkyl having 1 to 4 inclusive carbon atoms, or acyl --CO--R' in which R' represents alkyl having 1 to 4 inclusive carbon atoms,X represents O or H.sub.2,an isomer,and an addition salt thereof with a pharmaceutically-acceptable acid or base, andmedicinal products containing the same which are useful in treating or in preventing disorder resulting from or associated with phenomena of peroxidation and disturbance of the synthesis of eicosanoids.