title: Investigation of Uña De Gato I. 7-Deoxyloganic acid and 15N NMR spectroscopic studies on pentacyclic oxindole alkaloids from Uncaria tomentosa.
abstract: The C-8-(S) isomer of deoxyloganic acid (7-deoxyloganic acid), together with beta-sitosteryl glucoside, five known stereoisomeric pentacyclic oxindole alkaloids and the tetracyclic oxindole isorhyncophylline, were isolated from the inner bark of Uncaria tomentosa. Structures of the isolated compounds were based on 1H and 13C NMR data, mainly 2D NMR experiments, including 1H-13C HMBC and 1H-1H NOESY correlation. Furthermore, the hitherto unreported 15N chemical shifts of the isomeric oxindole alkaloids, using 1H-15N HMBC experiments, were utilized to facilitate their characterization. Uncarine D showed weak cytotoxic activity against SK-MEL, KB, BT-549 and SK-OV-3 cell lines with IC(50) values between 30 and 40 microg/ml, while uncarine C exhibited weak cytotoxicity only against ovarian carcinoma (IC(50) at 37 microg/ml).
authors.affiliation: National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS 38677, USA. milias@sunset.backbone.olemiss.edu
authors.forename: I
authors.initials: I
authors.lastname: Muhammad
authors.forename: D C
authors.initials: DC
authors.lastname: Dunbar
authors.forename: R A
authors.initials: RA
authors.lastname: Khan
authors.forename: M
authors.initials: M
authors.lastname: Ganzera
authors.forename: I A
authors.initials: IA
authors.lastname: Khan
mesh_terms: D000470:Alkaloids / Q000737:chemistry*; D006801:Humans; D007211:Indoles / Q000737:chemistry*; D039823:Iridoids; D009682:Magnetic Resonance Spectroscopy; D009587:Nitrogen Isotopes; D019666:Rubiaceae / Q000737:chemistry*; D014407:Tumor Cells, Cultured
chemical_list: C432876:7-deoxyloganic acid; D000470:Alkaloids; D007211:Indoles; D039823:Iridoids; D009587:Nitrogen Isotopes