title: [Screening of a Lactobacillus casei with monoamine oxidase-inhibitory activity].
abstract: OBJECTIVE
  To screen for monoamine oxidase (MAO)-inhibiting lactobacillus from healthy human dejecta in an in vitro model, and to provide reference for anti-ageing study in vivo of lactobacillus in the future.
  
  
  METHODS
  The monoamine oxidase inhibitory model in vitro was applied to screen fermented supernatant and cell-free extracts originated from lactic acid bacteria, and two indices based on screened samples were determined, including biological dosage-effect and the effect of pre-incubated time between MAO and inhibitor on suppression rate. Meanwhile, with membrane separation technology, MAO inhibition from different molecular weight range of samples was measured. Screened strain JH-23 was investigated as target probiotic lactobacillus, identified through the sequence analysis of 16S rDNA gene and API system.
  
  
  RESULTS
  The MAO inhibitory rate of cell-free extracts produced by strain JH-23 reached 33.7%. After samples being vacuum freeze-dried, MAO inhibitory rate was up to 53.2% when the reactive concentration was 16 mg/mL. The inhibition was significantly enhanced with the duration of pre-incubation increased, and then the inhibitory effect became steady after 30 minutes. Crude samples were dialyzed for 48 hours, MAO inhibitory effect of dialysates was significantly increased compared with pre-dialysis. The result of bacteria identification demonstrated that strain JH-23 was ascribed to Lactobacillus casei.
  
  
  CONCLUSIONS
  A new screening model in vitro, regarding monoamine oxidase as a target enzyme, was explored in this study. This model was characterized by convenience, rapidity and high sensitivity, and it could be useful for the following anti-aging research in vivo. The cell-free extracts of Lactobacillus casei JH-23 was inhibitory to MAO, and the intracellular small-molecules played a major role in the inhibition.
authors.affiliation: Food College of Shanghai Ocean University, Shanghai 201306, China. wanghao840818@126.com
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Benheng
authors.initials: B
authors.lastname: Guo
authors.forename: Zhengjun
authors.initials: Z
authors.lastname: Wu
authors.forename: Yinyu
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000818:Animals; D005243:Feces / Q000382:microbiology*; D006801:Humans; D007700:Kinetics; D007780:Lacticaseibacillus casei / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D008099:Liver / Q000737:chemistry / Q000201:enzymology; D008995:Monoamine Oxidase / Q000737:chemistry / Q000378:metabolism; D008996:Monoamine Oxidase Inhibitors / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D008996:Monoamine Oxidase Inhibitors; D008995:Monoamine Oxidase