title: Limonoids from Azadirachta excelsa.
abstract: Activity-directed fractionation of a stem extract of Azadirachta excelsa using KB (human oral epidermoid carcinoma) cells led to the isolation of four meliacin-type limonoids. Two of these constituents were novel, namely, 2,3-dihydronimbolide and 3-deoxymethylnimbidate, and these were purified along with the known compounds, nimbolide and 28-deoxonimbolide. The structures of the new compounds were determined by spectroscopic methods. Nimbolide and 28-deoxonimbolide were broadly cytotoxic when evaluated against a panel of human cancer cell lines, while the two novel compounds were inactive in this regard. The defection of nimbolide and 28-deoxonimbolide as cytotoxic constituents was facilitated by an electrospray LC/MS dereplication procedure.
authors.affiliation: Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago 60612, USA.
authors.forename: B
authors.initials: B
authors.lastname: Cui
authors.forename: H
authors.initials: H
authors.lastname: Chai
authors.forename: H L
authors.initials: HL
authors.lastname: Constant
authors.forename: T
authors.initials: T
authors.lastname: Santisuk
authors.forename: V
authors.initials: V
authors.lastname: Reutrakul
authors.forename: C W
authors.initials: CW
authors.lastname: Beecher
authors.forename: N R
authors.initials: NR
authors.lastname: Farnsworth
authors.forename: G A
authors.initials: GA
authors.lastname: Cordell
authors.forename: J M
authors.initials: JM
authors.lastname: Pezzuto
authors.forename: A D
authors.initials: AD
authors.lastname: Kinghorn
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D002770:Cholenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D007783:Lactones / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D036701:Limonins; D010946:Plants, Medicinal / Q000737:chemistry*; D012632:Secosteroids / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D013057:Spectrum Analysis; D014407:Tumor Cells, Cultured
chemical_list: C112676:2,3-dihydronimbolide; C112677:3-deoxymethylnimbidate; D000972:Antineoplastic Agents, Phytogenic; D002770:Cholenes; D004224:Diterpenes; D007783:Lactones; D036701:Limonins; D012632:Secosteroids; C062897:28-deoxonimbolide; C042198:nimbolide