Search results for "guaianolide"
showing 3 items of 3 documents
Guaianolides from the aerial parts of Centaurea hololeuca
2006
Seven guaianolides were isolated from the acetone extract of the aerial parts of Centaurea hololeuca Boiss. The antifeedant activity of the natural compounds (1-7) and of four chloro derivatives (8-11), synthesized from repin (1) and janerin (3) were tested against larvae of Spodoptera littoralis. Cebellin J (6) and chlorojanerin (11) showed significant antifeedant activity at 100 ppm, whereas at this concentration cebellin G (4) and 15-deschloro-15- hydroxychlorojanerin (7) stimulated feeding. Cebellin G (4) stimulated larvae of S. littoralis to feed at low concentration, but deterred feeding at high concentrations. The addition of chlorine to repin (1) resulted in an increase in antifeeda…
The first example of natural cyclic carbonate in terpenoids
2006
Abstract The first natural occurring cyclic carbonate terpenoid, the guaianolide hololeucin ( 1 ), was isolated from the aerial part of Centaurea hololeuca . Its structure was elucidated on the basis of extensive proton, 13 C and two-dimensional NMR experiments, as well as by transformation in its diacetyl derivative.