The structural evolution of β-secretase inhibitors: a focus on the development of small-molecule inhibitors.
Effective treatment of Alzheimer's disease (AD) remains a critical unmet need in medicine. The lack of useful treatment for AD led to an intense search for novel therapies based on the amyloid hypothesis, which states that amyloid β-42 (Aβ42) plays an early and crucial role in all cases of AD. β-Secretase (also known as BACE-1 β-site APP-cleaving enzyme, Asp-2 or memapsin-2) is an aspartyl protease representing the rate limiting step in the generation of Aβ peptide fragments, therefore it could represent an important target in the steady hunt for a disease-modifying treatment. Generally, β-secretase inhibitors are grouped into two families: peptidomimetic and nonpeptidomimetic inhibitors. However, irrespective of the class, serious challenges with respect to blood-brain barrier (BBB) penetration and selectivity still remain. Discovering a small molecule inhibitor of β-secretase represents an unnerving challenge but, due to its significant potential as a therapeutic target, growing efforts in this task are evident from both academic and industrial laboratories. In this frame, the rising availability of crystal structures of β-secretase-inhibitor complexes represents an invaluable opportunity for optimization. Nevertheless, beyond the inhibitory activity, the major issue of the current research approaches is about problems associated with BBB penetration and pharmacokinetic properties. This review follows the structural evolution of the early β-secretase inhibitors and gives a snap-shot of the hottest chemical templates in the literature of the last five years, showing research progress in this field.
European Research Centre for Drug Discovery and Development (NatSynDrugs), University of Siena, Via Aldo Moro, 2, 53100 Siena, Italy.
Stefania
S
Butini
Simone
S
Brogi
Ettore
E
Novellino
Giuseppe
G
Campiani
Arun K
AK
Ghosh
Margherita
M
Brindisi
Sandra
S
Gemma
D000544:Alzheimer Disease / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D016282:Aspartic Acid Endopeptidases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D001812:Blood-Brain Barrier; D002199:Capillary Permeability; D015195:Drug Design; D006801:Humans; D057786:Peptidomimetics / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000627:therapeutic use; D011480:Protease Inhibitors / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000627:therapeutic use; D054852:Small Molecule Libraries / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000627:therapeutic use
D016229:Amyloid beta-Peptides; D057786:Peptidomimetics; D011480:Protease Inhibitors; D054852:Small Molecule Libraries; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human