title: Methylations of tryptophan-modified naphthoquinone affect its inhibitory potential toward Aβ aggregation.
abstract: Aggregation of amyloid beta (Aβ) is the hallmark of Alzheimer's disease (AD). Small molecules inhibiting Aβ can be valuable therapeutics for AD. We have previously reported that 1,4-naphthoquinon-2-yl-l-tryptophan (NQTrp), reduces aggregation and oligomerization of Aβ in vitro and in vivo. In silico analysis further showed that certain functional groups of NQTrp, not in the aromatic rings, are also involved in binding and inhibiting Aβ. To better understand the exact mode of action and identify the groups crucial for NQTrp inhibitory activity, we conducted structure-activity analysis. Four derivatives of NQTrp were studied in silico: a D-isomer, two single-methylated and one double-methylated derivative. In silico results showed that the NQTrp groups involved in hydrogen bonds are the anilinic NH (i.e., the NH linker between the quinone and tryptophan moieties), the quinonic carbonyls, and the carboxylic acid. These predictions were supported by in vitro results. Our results should aid in designing improved small-molecule inhibitors of Aβ aggregation for treating AD.
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Tel-Aviv University, Tel-Aviv 69978, Israel.
authors.forename: Roni
authors.initials: R
authors.lastname: Scherzer-Attali
authors.forename: Marino
authors.initials: M
authors.lastname: Convertino
authors.forename: Riccardo
authors.initials: R
authors.lastname: Pellarin
authors.forename: Ehud
authors.initials: E
authors.lastname: Gazit
authors.forename: Daniel
authors.initials: D
authors.lastname: Segal
authors.forename: Amedeo
authors.initials: A
authors.lastname: Caflisch
mesh_terms: D000544:Alzheimer Disease / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005454:Fluorescence Polarization; D006801:Humans; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D009285:Naphthoquinones / Q000138:chemical synthesis / Q000737:chemistry* / Q000627:therapeutic use; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry* / Q000627:therapeutic use
chemical_list: C582984:1,4-naphthoquinon-2-yltryptophan; D016229:Amyloid beta-Peptides; D009285:Naphthoquinones; D010446:Peptide Fragments; C433241:amyloid beta-protein (1-16); C075222:amyloid beta-protein (1-42); D014364:Tryptophan