title: Alkaloids from the stem bark of Micromelum falcatum.
abstract: Two new quinoldione alkaloids, methyl 2-(3-hydroxy-1-methyl-2,4-dioxo-1,2,3,4-tetrahydroquinolin-3-yl)acetate (1) and 3-hydroxy-1-methyl-3-(2-oxopropyl)quinoline-2,4(1H,3H)-dione (2), and two quinolinone alkaloids previously synthesized but first isolated as natural products, N-methylflindersine (3) and 4-hydroxy-3-methoxy-1-methyl-2(1H)-quinolinone (4), were isolated from the stem bark of Micromelum falcatum, together with the known N-methylswietenidine-B (5). Their structures were established mainly on the basis of 1D- and 2D-NMR techniques. All compounds were evaluated for toxicity towards brine shrimp larvae, and 3 showed strong toxicity with an LD(50) value of 1.39 microg/ml.
authors.affiliation: Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
authors.forename: Xiong Ming
authors.initials: XM
authors.lastname: Luo
authors.forename: Shu Hua
authors.initials: SH
authors.lastname: Qi
authors.forename: Hao
authors.initials: H
authors.lastname: Yin
authors.forename: Cheng Hai
authors.initials: CH
authors.lastname: Gao
authors.forename: Si
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000470:Alkaloids / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000302:isolation & purification / Q000494:pharmacology; D001156:Artemia; D004354:Drug Screening Assays, Antitumor; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D024301:Plant Bark / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D011804:Quinolines / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D027821:Rutaceae / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
chemical_list: C541671:3-hydroxy-1-methyl-3-(2-oxopropyl)quinoline-2,4(1H,3H)-dione; D000470:Alkaloids; D000972:Antineoplastic Agents, Phytogenic; D007202:Indicators and Reagents; D011804:Quinolines; C541670:methyl 2-(3-hydroxy-1-methyl-2,4-dioxo-1,2,3,4-tetrahydroquinolin-3-yl)acetate