chemical composition of the essential oil of the fruit of ferula assafoetida l. obtained by steam distillation solvent extraction methodhas been studied by gc/ms for the first time. fifty-four components, comprising 96.9% of the total oil, were identified.epi-α-cadinol (23.15 %), germacrene b (10.98 %), α-gurjunene (6.18 %), (z)-1-propenyl secbutyl disulfide (5.89 %), 5-epi-7-epi-α-eudesmol (4....

Chicory (Cichorium intybus) sesquiterpene lactones were recently shown to be derived from a common sesquiterpene intermediate, (+)-germacrene A. Germacrene A is of interest because of its key role in sesquiterpene lactone biosynthesis and because it is an enzyme-bound intermediate in the biosynthesis of a number of phytoalexins. Using polymerase chain reaction with degenerate primers, we have i...

Germacrene C was found by GC-MS and NMR analysis to be the most abundant sesquiterpene in the leaf oil of Lycopersicon esculentum cv. VFNT Cherry, with lesser amounts of germacrene A, guaia-6,9-diene, germacrene B, b-caryophyllene, a-humulene, and germacrene D. Soluble enzyme preparations from leaves catalyzed the divalent metal ion-dependent cyclization of [1-3H]farnesyl diphosphate to these s...

Hydro-distilled volatile oils from the flowers and leaves of Eupatorium cannabinum L. which gathered in Touchal on Mountain Alborz (Tehran province) in Iran were investigated mainly by a combination of GC and GC/MS. Thirty-nine components were identified in the oils. The main constituents of the essential oils in flowers and leaves were germacrene D (27.3%, 37.1%), gemacrene B (12.4%, 11.7%) an...

Essential oils that contain large concentrations of germacrene D are typically accompanied by cadinane sesquiterpenoids. The acid-catalyzed cyclization of germacrene D to give cadinane and selinane sesquiterpenes has been computationally investigated using both density functional (B3LYP/6-31G(*)) and post Hartree-Fock (MP2/6-31G(* *)) ab initio methods. The calculated energies are in general ag...

Segregation analysis between Lysopersicon esculentum (cultivated tomato) and L. hirsutum (wild form) in conjunction with positional verification by using near-isogenic lines demonstrated that biosynthesis of two structurally different classes of sesquiterpenes in these species is controlled by loci on two different chromosomes. A locus on chromosome 6, Sesquiterpene synthase1 (Sst1), was identi...

Germacrene A synthase (GAS) from Solidago canadensis catalyzes the conversion of farnesyl diphosphate (FDP) to the plant sesquiterpene (+)-germacrene A. After diphosphate expulsion, farnesyl cation reacts with the distal 10,11-double bond to afford germacrene A (>96%) and <2% α-humulene, which arises from 1,11-cyclization of FDP. The origin of the 1,11-activity of GAS was investigated by amino ...

A small library of novel germacrenes was generated using a combination of two plant enzymes, germacrene A synthase, and D synthase and modified farnesyl diphosphate (FDP) analogues. This chemoenzymatic approach allows the preparation of potentially valuable volatiles for biological studies.

The sesquiterpene costunolide has a broad range of biological activities and is the parent compound for many other biologically active sesquiterpenes such as parthenolide. Two enzymes of the pathway leading to costunolide have been previously characterized: germacrene A synthase (GAS) and germacrene A oxidase (GAO), which together catalyse the biosynthesis of germacra-1(10),4,11(13)-trien-12-oi...