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.

Scilla bifolia Wax as a Source of Diverse Long-Chain Resorcinols and Alkane-1,3-diols.

GC, GC/MS and NMR analyses of Scilla bifolia washings allowed for the identification of thirty-six long-chain compounds belonging to six homologous series (five of which are from the class of resorcinols, a group of biologically important phenols): 1-alkyl-3,5-dimethoxybenzenes, 5-alkyl-3-methoxy-2-methylphenols, 3-alkyl-5-methoxyphenols, 5-alkyl-2-methylresorcinols (five compounds from each of the series); 5-alkylresorcinols (six compounds) and 1,3-alkanediols (ten compounds). Many of these compounds rarely occur in Nature. Retention indices of these compounds, as well as indices of the corresponding trimethylsilyl derivatives, were reported, some of them for the first time. The exact regiochemistry was unambiguously determined by two-dimensional NMR experiments; in some cases, the complete NMR assignment was augmented by computer spin-simulation of 1 H-NMR spectra.

Immunomodulatory activity of marine natural products: Synthesis, spectral characterization and toxicity assessment of natural and related synthetic iodinated tyramides.

The toxicity of natural marine iodoarenes or their synthetic counterparts is widely unknown despite the fact that triiodothyronine and thyroxine are members of this class. In this work we aimed to expand such knowledge on iodinated marine natural products and tested an ascidian (Didemnum rubeum) metabolite, N-(3,5-diiodo-4-methoxyphenethyl)benzamide, together with closely related synthetic iodinated tyramides: N-(2,5-diiodo-4-methoxyphenethyl)benzamide, N-(3-iodo-4-methoxyphenethyl)benzamide, N-(4-methoxyphenethyl)benzamide, and N-(3-iodo-4-methoxyphenethyl)formamide, for their effect on the viability of rat macrophages, as well as acute toxicity on Artemia salina. The tested tyramides exerted a varying degree of toxicity towards brine shrimps, but in certain cases, the determined lethal concentrations were even lower than those of known toxicants (e.g. strychnine sulfate, SDS). The toxicity was highly dependent on the structure of these mutually related compounds, while the natural one was shown to be the most toxic. In the case of macrophage cultures, the tested tyramides exerted much less toxicity but were found to have an effect on the functioning of these normal immune cells. The samples of the tyramides were obtained by synthesis, and were fully structurally and spectrally characterized, which also provided corroboration of the proposed structure of the natural product originally isolated in minute amounts.

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.