title: Natural Products Screening for the Identification of Selective Monoamine Oxidase-B Inhibitors.
abstract: OBJECTIVE
  Monoamine oxidase-B inhibitors (MAO-BIs) are used for the initial therapy of Parkinson's disease. Also, MAO-BIs have shown to be effective neuroprotective agents in several neurodegenerative diseases. However, some concerns exist regarding the long-term use of these compounds. Meanwhile, natural compounds showed potential MAO-B selective inhibitions. To date, few selective natural MAO-BIs have been identified. Therefore, the current study is designed to identify plants with potent and specific MAO-B inhibition.
  
  
  METHODS
  In this work, we utilized high throughput screening to evaluate the different plants ethanolic extract for their effectiveness to inhibitrecombinant human(h)MAO-A andhMAO-B and to determine the relative selectivity of the top MAO-BI.
  
  
  METHODS
  Recombinant human isozymes were verified by Western blotting, and the 155 plants were screened. A continuous fluorometric screening assay was performed followed by two separatehMAO-A andhMAO-B microtiter screenings and IC50determinations for the top extracts.
  
  
  RESULTS
  In the screened plants, 9% of the extracts showed more than 1.5-fold relative inhibition ofhMAO-B (RIB) and another 9% showed more than 1.5-fold relative inhibition ofhMAO-A. The top extracts with the most potent RIBs werePsoralea corylifoliaseeds,Phellodendron amurensebark,Glycyrrhiza uralensisroots, andFerula assafoetidaroots, with the highest RIBof 5.9-fold. Furthermore, extensive maceration of the promising extracts led to increase inhibitory effects with a preserved RIBas confirmed with luminescence assay. The top four extractshMAO-BIs were equally potent (IC50= 1.3 to 3.8 μg/mL) with highly significant relative selectivities to inhibithMAO-B (4.1- to 13.4-fold).
  
  
  CONCLUSIONS
  The obtained results indicate thatPsoralea corylifoliaseeds,Ferula assafoetida, Glycyrrhiza uralensisroots, andPhellodendron amurenseethanolic extracts have selective inhibitions for human MAO-B. Investigating these plant extracts as natural resources for novel selective MAO-BIs may lead to the development of molecules that can be used in the therapeutic management of neurodegenerative diseases including Parkinson's disease.
authors.affiliation: College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, Florida 32307, USA.
authors.forename: Najla O
authors.initials: NO
authors.lastname: Zarmouh
authors.affiliation: College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, Florida 32307, USA.
authors.forename: Samia S
authors.initials: SS
authors.lastname: Messeha
authors.affiliation: College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, Florida 32307, USA.
authors.forename: Faisel M
authors.initials: FM
authors.lastname: Elshami
authors.affiliation: College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, Florida 32307, USA.
authors.forename: Karam F A
authors.initials: KF
authors.lastname: Soliman
keywords: Ferula assafoetida; Glycyrrhiza uralensis; Parkinson disease; Phellodendron amurense; Psoralea corylifolia seeds; selective monoamine oxidase-B inhibitors