It relates to certain compounds having a polycyclic structure and a hydroxamic acid moiety, wherein the polycyclic structure comprises at least three ring systems, wherein one ring system is a polycyclic ring system comprising from 2 to 4 rings； at least one ring is an aromatic ring； and wherein the structure comprises at least 3 nitrogen atoms and 1 oxygen atom. It also relates to a process for their preparation, as well as to pharmaceutical compositions containing them, and to their use in medicine, in particular in the treatment and/or prevention of neurological disorders coursing with a cognition deficit or impairment, or neurodegenerative diseases. wherein B1 is a radical selected from the group consisting of formula (A&Prime；), formula (B&Prime；), formula (C&Prime；), and formula (D&Prime；):
