title: Phytotoxic compounds from Prionosciadium watsoni.
abstract: Bioassay-guided fractionation of a phytotoxic extract of Prionosciadium watsoni led to the isolation of three new pyranocoumarins and two pyranochromones. The new compounds were characterized as propionic acid (9R,10R)-9-acetoxy-8,8-dimethyl-9,10-dihydro-2H,8H-benzo[1,2-b:3,4-b']dipyran-2-one-10-yl ester (1), isobutyric acid (9R,10R)-9-hydroxy-8,8-dimethyl-9,10-dihydro-2H,8H-benzo[1,2-b:3,4-b']dipyran-2-one-10-yl ester (2), isobutyric acid (9R)-8,8-dimethyl-9,10-dihydro-2H,8H-benzo[1,2-b:3,4-b']dipyran-2-one-9-yl ester (10), 2-methylbut-(2Z)-enoic acid (3R)-5-methoxy-3,4-dihydro-2,2,8-trimethyl-6-oxo-2H,6H-benzo[1,2-b:5,4-b']dipyran-3-yl ester (11), and isobutyric acid (3R)- 5-methoxy-3,4-dihydro-2,2,8-trimethyl-6-oxo-2H,6H-benzo[1,2-b:5,4-b']dipyran-3-yl ester (12) by spectroscopic and chemical methods. The stereochemistry at the stereogenic centers was established by applying the Mosher ester methodology. The structures of 1 and 2 were corroborated by single-crystal X-ray diffraction studies. The phytotoxic activity of the isolated compounds was assessed on Amaranthus hypochondriacus, Echinochloa crus-galli, and Lemna pausicostata. The phytotoxins also modified the electrophoretic mobility of calmodulin from both bovine-brain and spinach.
authors.affiliation: Departamento de Farmacia, Facultad de Química, Universidad Nacional Autónoma de México, México, D.F. 04510, México.
authors.forename: Norma
authors.initials: N
authors.lastname: Valencia-Islas
authors.forename: Hamed
authors.initials: H
authors.lastname: Abbas
authors.forename: Robert
authors.initials: R
authors.lastname: Bye
authors.forename: Rubén
authors.initials: R
authors.lastname: Toscano
authors.forename: Rachel
authors.initials: R
authors.lastname: Mata
mesh_terms: D027721:Amaranthus / Q000187:drug effects; D000818:Animals; D019661:Apiaceae / Q000737:chemistry*; D001921:Brain; D002147:Calmodulin / Q000187:drug effects; D002417:Cattle; D018360:Crystallography, X-Ray; D004591:Electrophoresis, Polyacrylamide Gel; D006575:Heterocyclic Compounds, 3-Ring / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008800:Mexico; D008968:Molecular Conformation; D015394:Molecular Structure; D010946:Plants, Medicinal / Q000737:chemistry*; D010947:Plants, Toxic / Q000737:chemistry*; D018724:Spinacia oleracea / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: C464607:2-methylbut-(2Z)-enoic acid (3R)-5-methoxy-3,4-dihydro-2,2,8-trimethyl-6-oxo-2H,6H-benzo(1,2-b-5,4-b')dipyran-3-yl ester; D002147:Calmodulin; D006575:Heterocyclic Compounds, 3-Ring; C464608:isobutyric acid (3R)- 5-methoxy-3,4-dihydro-2,2,8-trimethyl-6-oxo-2H,6H-benzo(1,2-b-5,4-b')dipyran-3-yl ester; C464606:isobutyric acid (9R)-8,8-dimethyl-9,10-dihydro-2H,8H-benzo(1,2-b-3,4-b')dipyran-2-one-9-yl ester; C464605:isobutyric acid (9R,10R)-9-hydroxy-8,8-dimethyl-9,10-dihydro-2H,8H-benzo(1,2-b-3,4-b')dipyran-2-one-10-yl ester; C464604:propionic acid (9R,10R)-9-acetoxy-8,8-dimethyl-9,10-dihydro-2H,8H-benzo(1,2-b-3,4-b')dipyran-2-one-10-yl ester