title: Triterpenoids isolated from the rhizomes and roots of Gentiana scabra and their inhibition of indoleamine 2,3-dioxygenase.
abstract: Gentiana scabra Bunge (Gentianaceae) is an important traditional Chinese medicine commonly used as a stomachic or appetite stimulant. In this study, 21 triterpenoids (1-21) were isolated from a methanol extract of the rhizomes and roots of G. scabra. Their structures were elucidated by comparing spectroscopic data with reported values. Among the isolated triterpenoids, scabanol (2) was firstly isolated from natural sources. All isolated compounds were evaluated for their inhibitory activity against indoleamine 2,3-dioxygenase (IDO), which catalyzes the rate limiting reaction for the conversion of tryptophan to kynurenine. Compounds 10 and 11 showed significant inhibitory activities, with IC(50) values of 12.5 and 9.5 μM, respectively. Compound 12 showed a moderate inhibitory effect, with an IC(50) value of 18.7 μM. Compounds 2 and 13 showed weaker inhibitory effects, with IC(50) values of 56.8 and 60.6 μM, respectively. Kynurenine is a potent immune modulator to suppress the functions of a variety of immune cells including T cells and natural killer cells. Given that, our results that a few selected triterpenoids inhibit IDO warrant further studies on their effects on the host immune system as natural immune stimulators.
authors.affiliation: School of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbuk, 712-749, Korea.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: College of Pharmacy, Chungnam National University, Daejeon, 305-764, Korea.
authors.forename: Lin Ying
authors.initials: LY
authors.lastname: Li
authors.affiliation: College of Pharmacy, Yanbian University, Yanji, 133002, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.affiliation: College of Pharmacy, Chungnam National University, Daejeon, 305-764, Korea. hwanginkyu@cnu.ac.kr.
authors.forename: Inkyu
authors.initials: I
authors.lastname: Hwang
authors.affiliation: Center of Herbal Medicine Improvement Research, Korea Institute of Oriental Medicine, Daejeon, 305-811, Korea. jyma@kiom.re.kr.
authors.forename: Jin Yeul
authors.initials: JY
authors.lastname: Ma
authors.affiliation: College of Pharmacy, Chungnam National University, Daejeon, 305-764, Korea. yhk@cnu.ac.kr.
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
mesh_terms: D004791:Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D030012:Gentiana; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D018517:Plant Roots; D027343:Rhizome; D014315:Triterpenes / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D010936:Plant Extracts; D014315:Triterpenes
keywords: Gentiana scabra; Gentianaceae; IDO inhibition; Triterpenoid