- Coumarins from the fruits of Seseli devenyense
-
Eight new coumarins were isolated from the fruits of Seseli devenyense Simonkai. Their structures were established from NMR and mass data and their absolute configurations from chemical degradation correlation reactions. The new structures are the decanoic and dodecanoic esters of (+)-lomatin (3, 4), the decanoates of (+)-cis-khellactone at positions 4′ (5) and 3′ (6) as well as the 2′S epimer of 8-(2,3-dihydroxy-3-methylbutyl)-7- hydroxychromen-2-one (7) named devenyol, its two O-monoglucosides at positions 3′ and 7 named devenyosides A (8) and B (9), and the corresponding 3′- and 7-O-diglucoside named devenyoside C (10). This plant is an interesting example of stereochemical diversity based on biodiversity given that other members of the Apiaceae family produce exclusively the 2′R epimers of compounds 7-9.
- Widelski, Jarek,Melliou, Eleni,Fokialakis, Nikolas,Magiatis, Prokopios,Glowniak, Kazimierz,Chinou, Ioanna
-
p. 1637 - 1641
(2008/09/17)
-
- Phytotoxic compounds from Prionosciadium watsoni
-
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.
- Valencia-Islas, Norma,Abbas, Hamed,Bye, Robert,Toscano, Ruben,Mata, Rachel
-
p. 828 - 834
(2007/10/03)
-