Inhibition of Human Monoamine Oxidases A and B by Specialized Metabolites Present in Fresh Common Fruits and Vegetables

Abstract

Diets rich in fruits and vegetables are associated with better psychological wellbeing and cognitive functions, although it is unclear which molecules and mechanisms are involved. One potential explanation is the inhibition of monoamine oxidases (MAOs), which have been linked to several neurological disorders. The present study investigated the ability of kiwifruit to inhibit MAO-A and MAO-B, refining an in vitro assay to avoid confounding effects. Ultra-performance liquid chromatography/mass spectrometry (UPLC-QTOF) and nuclear magnetic resonance spectroscopy (NMR) were used to select individual kiwifruit metabolites for further analysis. Moreover, extracts of other common fruits and vegetables were screened to identify promising candidate inhibitors. Multiple extracts and compounds inhibited both enzymes, and the selective inhibition of MAO-B by the major kiwifruit specialized metabolite D-(−)-quinic acid was observed. These results suggest that fruits and vegetables contain metabolites that inhibit the activity of MAO-A and -B, offering a potential natural option for the treatment of neurological disorders, in which MAOs are involved.

Screening of Monoamine Oxidase Inhibitors from Seeds of Nigella glandulifera Freyn et Sint. by Ligand Fishing and Their Neuroprotective Activity

“…This is the first report on the MAO-B inhibitory activity of both compounds while supporting the ethnomedicinal claims of N. glandulifera as an anti-neurodegenerative herb and a functional food. Furthermore, previous studies report that several compounds from herbal medicines, such as caffeic acid, catechin, and esculin, possess significant MAO-B inhibitory effects [ 44 , 45 , 46 , 47 ]. Our findings support the conclusion of previous studies that medicinal plants are a rich source for discovering inhibitors of MAO-B [ 46 , 47 ].…”

Untargeted Metabolomics Analysis of the Orchid Species Oncidium sotoanum Reveals the Presence of Rare Bioactive C-Diglycosylated Chrysin Derivatives

“…MAO-B activity was tested using a two-step bioluminescent MAO-Glo assay (Promega, Milan, Italy) as previously reported [ 88 ]. Briefly, 250 µL of flower, leaf or pseudobulb methanol extract was placed in a speedvac (Heto-Holten, Frederiksborg, Denmark) to remove the solvent, and the dry pellets were solubilized in 250 µL of MAO reaction buffer, comprising 100 mM HEPES (pH 7.5), 5% ( v / v ) glycerol and 10% ( v / v ) dimethyl sulfoxide (DMSO).…”

The Advent of Nutrigenomics: A Narrative Review with an Emphasis on Psychological Disorders

“…ID and MAOA polymorphisms in humans suggest that this association may be a significant predictor of cognitive abilities ( Golub and Hogrefe, 2014 ). The discovery that fruits and vegetables contain metabolites that inhibit MAO-A and -B activity provides a natural treatment option for neurological disorders ( Marzo et al, 2022 ).…”