New neryl esters from Helichrysum italicum (Roth) G. Don (Asteraceae) essential oil.

Helichrysum italicum (immortelle) is a dwarf aromatic shrub native to the Mediterranean region. The typical subspecies (italicum) produces an essential oil rich in neryl acetate and characteristic ß-diketones, italidiones, highly valued in the perfume industry. As esters are an important group of aroma-active volatiles, herein the composition of the ester fraction of this immortelle chemotype essential oil was studied in detail. Chromatographic separation of Corsican immortelle essential oil enabled the discovery of numerous potentially olfactory-interesting esters of nerol and/or angelic acid, undetectable by direct GC-MS analyses of the unfractioned oil. Four esters of nerol and medium-chain branched fatty acids represent new natural products, while several other esters have a rather restricted occurrence in the Plant Kingdom.

Chemical Composition of the Essential Oil and Diethyl Ether Extract of Trinia glauca (L.) Dumort. (Apiaceae) and the Chemotaxonomic Significance of 5-O-Methylvisamminol.

Analyses by GC, GC/MS, and NMR spectroscopy (1D- and 2D-experiments) of the essential oil and Et2O extract of Trinia glauca (L.) Dumort. (Apiaceae) aerial parts allowed a successful identification of 220 constituents, in total. The major identified compounds of the essential oil were (Z)-falcarinol (10.6%), bicyclogermacrene (8.0%), germacrene D (7.4%), δ-cadinene (4.3%), and ß-caryophyllene (3.2%), whereas (Z)-falcarinol (47.2%), nonacosane (7.4%), and 5-O-methylvisamminol (4.0%) were the dominant constituents of the extract of T. glauca. One significant difference between the compositions of the herein and the previously analyzed T. glauca essential oils (only two reports) was noted. (Z)-Falcarinol was the major constituent in our case, whereas germacrene D (14.4 and 19.6%) was the major component of the previously studied oils. Possible explanations for this discrepancy were discussed. 5-O-Methylvisamminol, a (furo)chromone identified in the extract of T. glauca, has a limited occurrence in the plant kingdom and is a possible excellent chemotaxonomic marker (family and/or subfamily level) for Apiaceae.

Chemical composition of the tuber essential oil from Helianthus tuberosus L. (Asteraceae).

Helianthus tuberosus L. (Jerusalem artichoke) is cultivated in Europe and other parts of the world as a food crop and ornamental plant. The volatile oils of the aerial parts of H. tuberosus were investigated more than 30 years ago, but no study could be found to date on the constituents of the tuber essential oil. Herein, the first characterization by GC-FID, GC/MS, and (13) C-NMR analyses of a hydrodistilled essential oil of Jerusalem artichoke tubers was reported. Fresh plant material collected in Serbia (Sample A) and a commercial sample (Sample B) yielded only small amounts of oil (0.0014 and 0.0021% (w/w), resp.). In total, 195 constituents were identified, representing 88.2 and 93.6% of the oil compositions for Samples A and B, respectively. The main constituents identified were ß-bisabolene (1; 22.9-30.5%), undecanal (0-12.7%), α-pinene (7.6-0.8%), kauran-16-ol (2; 6.9-9.8%), 2-pentylfuran (0.0-5.7%), and (E)-tetradec-2-enal (0.0-4.9%). Several rare compounds characteristic for Helianthus ssp. were also detected: helianthol A (6; 2.1-1.9%), dihydroeuparin (10; 0.0-2.3%), euparin (9; 0.0-0.4%), desmethoxyencecalin (7; traces - 0.2%), desmethylencecalin (8; 0.0-0.4%), and an isomer of desmethylencecalin (0.0%-traces). The essential oils isolated from the tuber and the aerial parts share the common major component 1.