Homoisoflavonoids: Natural Scaffolds with Potent and Selective Monoamine Oxidase-B Inhibition Properties

Abstract

A series of homoisoflavonoids [(E)-3-benzylidenechroman-4-ones 1a-w, 3-benzyl-4H-chromen-4-ones 2a-g, and 3-benzylchroman-4-ones 3a-e] have been synthesized and tested in vitro as inhibitors of human monoamine oxidase isoforms A and B (hMAO-A and hMAO-B). Most of the compounds were found to be potent and selective MAO-B inhibitors. In general, the (E)-3-benzylidenechroman-4-ones 1a-w showed activities in the nano- or micromolar range coupled with high selectivity against hMAO-B. The reduction of the exocyclic double bond results in compounds 3a-e selective against isoform B and active in the micromolar range. In contrast, the endocyclic migration of the double bond (compounds 2a-g) generally produces the loss of the inhibitory activity or a marked reduction in potency. (E)-3-(4-(Dimethylamino)benzylidene)chroman-4-one (1l) and (E)-5,7-dihydroxy-3-(4-hydroxybenzylidene)chroman-4-one (1h) were the most interesting compounds of the entire series of inhibitors, showing hMAO-B affinity better than the selective inhibitor selegiline. Molecular modeling studies have been carried out to explain the selectivity of the most active homoisoflavonoids 1h and 1l.

Synthesis of a series of unsaturated ketone derivatives as selective and reversible monoamine oxidase inhibitors

“…Next, an aliquot of the enzyme solution with 2 μM of each compound was washed using an effective centrifugation-ultrafiltration method. 26 The activities of MAO-B were almost recovered after repeated washout of MAO-B inhibitors 10b and 10e, indicating that they are fully reversible inhibitors. However, irreversible inhibitor selegiline showed no recovery of hMAO-B activity in the same assay (Fig.…”

Quantitative Structure-cytotoxicity Relationship of 3-Benzylidenechromanones

“…(3E)-2,3-Dihydro-3-(phenylmethylene)-4H-1-benzopyran-4-one [1], (3E)-2,3-dihydro-3-[(4-hydroxyphenyl) methylene]-4H-1-benzopyran-4-one [2], (3E)-2,3-dihydro-3-[(3,4-dihydroxyphenyl)methylene]-4H-1-benzopyran-4-one [3], (3E)-2,3-dihydro-3-[(4-methoxyphenyl)methylene]-4H-1-benzopyran-4-one [4], (3E)-2,3-dihydro-3-[(3,4-dimethoxyphenyl)methylene]-4H-1-benzopyran-4-one [5], (3E)-2,3-dihydro-3-[(4-dimethylaminophenyl)methylene]-4H-1-benzopyran-4-one [6], (3E)-2,3-dihydro-3-[(4-fluorophenyl)methylene]-4H-1-benzopyran-4-one [7], (3E)-3-[(4-chlorophenyl)methylene]-2,3-dihydro-4H-1-benzopyran-4-one [8], (3E)-2,3-dihydro-7-hydroxy-3-[(4-hydroxyphenyl)methylene]-4H-1-benzopyran-4-one [9], (3E)-2,3-dihydro-3-[(3,4-dihydroxyphenyl)methylene]-7-hydroxy-4H-1-benzopyran-4-one [10], (3E)-2,3-dihydro-7-hydroxy-3-[(4-methoxyphenyl)methylene]-4H-1-benzopyran-4-one [11], (3E)-2,3-dihydro-3-[(4-dimethylaminophenyl)methylene]-7-hydroxy-4H-1-benzopyran-4-one [12], (3E)-2,3-dihydro-7-methoxy-3-(phenylmethylene)-4H-1-benzopyran-4-one [13], (3E)-2,3-dihydro-3-[(4-hydroxyphenyl)methylene]-7-methoxy-4H-1-benzopyran-4-one [14], (3E)-2,3-dihydro-3-[(3,4-dihydroxyphenyl)methylene]-7-methoxy-4H-1-benzopyran-4-one [15], (3E)-2,3-dihydro-7-methoxy-3-[(4-methoxyphenyl)methylene]-4H-1-benzopyran-4-one [16] and (3E)-2,3-dihydro-3-[(4-dimethylaminophenyl)methylene]-7-methoxy-4H-1-benzopyran-4-one [17] (structures shown in Figure 1) were synthesized by base-catalyzed condensation of appropriate 4-chromanone with substituted benzaldehyde derivatives according to previous methods (19,20). All compounds were dissolved in DMSO at 40 mM and stored at -20˚C before use.…”

Evaluation of the oxidation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to toxic pyridinium cations by monoamine oxidase (MAO) enzymes and its use to search for new MAO inhibitors and protective agents

“…Thus, inhibition of MAO may afford neuroprotection through a lower production of reactive oxygen species (ROS) and aldehydes, as well as a diminished activation of toxins such as MPTP and/ or related substances 2,6,16,17 . Therefore, studying MAO enzymes and finding new MAO inhibitors as purported neuroprotectants is a subject of current interest in drug discovery 1,[18][19][20][21][22][23][24][25][26] . MAO enzymes are usually monitored by measuring the absorbance and/or fluorescence of the oxidation products generated from key amines (kynuramine, tryptamine, tyramine, etc) [27][28][29][30][31][32][33] .…”