title: Chemical Components fromAloeand their Inhibition of Indoleamine 2, 3-dioxygenase.
abstract: BACKGROUND
  In Korea,Aloeis routinely ingested as a traditional medicine or as a component of health beverages.
  
  
  OBJECTIVE
  To research the inhibition of indoleamine 2, 3-dioxygenase (IDO) activities of components fromAloe.
  
  
  METHODS
  the compounds were isolated by a combination of silica gel and YMC Rp-18 column chromatography, and their structures were identified by analysis of spectroscopic data (1D, 2D-NMR, and MS). All of the isolated compounds were examined for their ability to inhibit IDO, which actively suppresses immune functions by catalyzing the rate limiting reaction in the conversion of tryptophan to kynurenine.
  
  
  RESULTS
  In this phytochemical study, 18 known compounds were isolated from aqueous dissolvedAloeexudates. All of the isolated compounds were examined for their ability to inhibit IDO activities for a series of anthraquinone derivatives (1-7) isolated from theAloeextract; the IC50values of these compounds ranged from 39.41 to 53.93 µM. Enzyme kinetic studies of their modes of inhibition indicated that all of the compounds were uncompetitive inhibitors.
  
  
  CONCLUSIONS
  The aqueous dissolvedAloeexudate can be used as a source of novel natural IDO inhibitors and merit testing as therapeutic agents in the treatments of cancer and immunopathologic diseases, such as autoimmune, inflammatory, and allergic disorders.
  
  
  CONCLUSIONS
  In this study, 18 known compounds were isolated from aqueous dissolved Aloe exudates. All of the isolated compounds were examined for their ability to inhibit indoleamine 2, 3-dioxygenase (IDO) activities for a series of anthraquinone derivatives (1-7) isolated from the Aloe extract.Abbreviation used:IDO: inhibit indoleamine 2, 3-dioxygenase, TMS: tetramethylsilane, HMQC: heteronuclear multiple quantum correlation, HMBC: heteronuclear multiple bond correlation, COSY: 1H-1H correlation spectroscopy, ESI-MS: Electrospray ionization mass spectrometry, DMSO: dimethyl sulfoxide.
authors.affiliation: College of Pharmacy, Chungnam National University, Daejeon, Korea.
authors.forename: Ya Nan
authors.initials: YN
authors.lastname: Sun
authors.affiliation: College of Pharmacy, Chungnam National University, Daejeon, Korea.
authors.forename: Lin Ying
authors.initials: LY
authors.lastname: Li
authors.affiliation: School of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbuk, Korea.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: College of Pharmacy, Chungnam National University, Daejeon, Korea.
authors.forename: Jong Seong
authors.initials: JS
authors.lastname: Kang
authors.affiliation: College of Pharmacy, Chungnam National University, Daejeon, Korea.
authors.forename: Inkyu
authors.initials: I
authors.lastname: Hwang
authors.affiliation: College of Pharmacy, Chungnam National University, Daejeon, Korea.
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
keywords: 3-dioxygenase (IDO); Aloe; Asphodelaceae; anthraquinone derivatives; indoleamine 2