Analysis of volatile components from<Emphasis Type="Italic"> Ziziphora taurica</Emphasis> subsp.<Emphasis Type="Italic"> taurica</Emphasis> by steam distillation,superheated-water extraction,and direct thermal desorption with GC×GC–TOFMS

Volatile components from the leaves of Ziziphora taurica subsp. taurica have been isolated by steam distillation, superheated-water extraction, and direct thermal desorption techniques. The volatile components were characterized by comprehensive two dimensional gas chromatography–time of flight mass spectrometry. The extraction yields from Z. taurica leaves were found to be 1.56% and 1.32% for steam distillation and superheated-water extraction respectively. The major compounds found in the volatile fractions of the leaves of Z. taurica were pulegone, terpinen-4-ol, cis-carveol, trans-carveol, and verbenone. The number of volatile components identified were 28, 30, and 41 for steam distillation, superheated-water extraction, and direct thermal desorption, respectively.This revised version replaces the article published online on March 2005.     

Chemical Composition and Antioxidant Activity of Essential Oils from Leaves of Two Specimens of Eugenia florida DC.

Eugenia florida DC. belongs to the Myrtaceae family, which is present in almost all of Brazil. This species is popularly known as pitanga-preta or guamirim and is used in folk medicine to treat gastrointestinal problems. In this study, two specimens of Eugenia florida (Efl) were collected in different areas of the same region. Specimen A (EflA) was collected in an area of secondary forest (capoeira), while specimen B (EflB) was collected in a floodplain area. The essential oils (EOs) were extracted from both specimens of Eugenia florida by means of hydrodistillation. Gas chromatography coupled to mass spectrometry (GC/MS) was used to identify the volatile compounds present, and the antioxidant capacity of the EOs was determined by antioxidant capacity (AC-DPPH) and the Trolox equivalent antioxidant (TEAC) assay. For E. florida, limonene (11.98%), spathulenol (10.94%) and α-pinene (5.21%) were identified as the main compounds of the EO extracted from sample A, while sample B comprised selina-3,11-dien-6α-ol (12.03%), eremoligenol (11.0%) and γ-elemene (10.70%). This difference in chemical composition impacted the antioxidant activity of the EOs between the studied samples, especially in sample B of E. florida. This study is the first to report on the antioxidant activity of Eugenia florida DC. essential oils.     

New Natural Oxygenated Sesquiterpenes and Chemical Composition of Leaf Essential Oil from Ivoirian Isolona dewevrei (De Wild. & T. Durand) Engl. & Diels

This study aimed to investigate the chemical composition of the leaf essential oil from Ivoirian Isolona dewevrei. A combination of chromatographic and spectroscopic techniques (GC(RI), GC-MS and ¹³C-NMR) was used to analyze two oil samples (S1 and S2). Detailed analysis by repetitive column chromatography (CC) of essential oil sample S2 was performed, leading to the isolation of four compounds. Their structures were elucidated by QTOF-MS, 1D and 2D-NMR as (10βH)-1β,8β-oxido-cadin-4-ene (38), 4-methylene-(7αH)-germacra-1(10),5-dien-8β-ol (cis-germacrene D-8-ol) (52), 4-methylene-(7αH)-germacra-1(10),5-dien-8α-ol (trans-germacrene D-8-ol) (53) and cadina-1(10),4-dien-8β-ol (56). Compounds 38, 52 and 53 are new, whereas NMR data of 56 are reported for the first time. Lastly, 57 constituents accounting for 95.5% (S1) and 97.1% (S2) of the whole compositions were identified. Samples S1 and S2 were dominated by germacrene D (23.6 and 20.5%, respectively), followed by germacrene D-8-one (8.9 and 8.7%), (10βH)-1β,8β-oxido-cadin-4-ene (7.3 and 8.7), 4-methylene-(7αH)-germacra-1(10),5-dien-8β-ol (7.8 and 7.4%) and cadina-1(10),4-dien-8β-ol (7.6 and 7.2%). Leaves from I. dewevrei produced sesquiterpene-rich essential oil with an original chemical composition, involving various compounds reported for the first time among the main components. Integrated analysis by GC(RI), GC-MS and ¹³C-NMR appeared fruitful for the knowledge of such a complex essential oil.     

Volatile Compounds of Lemon and Grapefruit IntegroPectin

An HS-SPME GC-MS analysis of the volatile compounds adsorbed at the outer surface of lemon and grapefruit pectins obtained via the hydrodynamic cavitation of industrial waste streams of lemon and grapefruit peels in water suggests important new findings en route to understanding the powerful and broad biological activity of these new pectic materials. In agreement with the ultralow degree of esterification of these pectins, the high amount of highly bioactive α-terpineol and terpinen-4-ol points to limonene (and linalool) decomposition catalyzed by residual citric acid in the citrus waste peel residue of the juice industrial production.     

The Chemical Compositions,and Antibacterial and Antioxidant Activities of Four Types of Citrus Essential Oils

Nanfeng mandarins (Citrus reticulata Blanco cv. Kinokuni), Xunwu mandarins (Citrus reticulata Blanco), Yangshuo kumquats (Citrus japonica Thunb) and physiologically dropped navel oranges (Citrus sinensis Osbeck cv. Newhall) were used as materials to extract peel essential oils (EOs) via hydrodistillation. The chemical composition, and antibacterial and antioxidant activities of the EOs were investigated. GC-MS analysis showed that monoterpene hydrocarbons were the major components and limonene was the predominate compound for all citrus EOs. The antibacterial testing of EOs against five different bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium) was carried out using the filter paper method and the broth microdilution method. Kumquat EO had the best inhibitory effect on B. subtilis, E. coli and S. typhimurium with MIC (minimum inhibitory concentration) values of 1.56, 1.56 and 6.25 µL/mL, respectively. All citrus EOs showed the antioxidant activity of scavenging DPPH and ABTS free radicals in a dose-dependent manner. Nanfeng mandarin EO presented the best antioxidant activity, with IC₅₀ values of 15.20 mg/mL for the DPPH assay and 0.80 mg/mL for the ABTS assay. The results also showed that the antibacterial activities of EOs might not be related to their antioxidant activities.     

Chemical composition and antimicrobial activity of the essential oils of Artemisia absinthium,Artemisia scoparia,and Artemisia sieberi grown in Saudi Arabia

Essential oils (EOs) are one of the most significant products of plant metabolites, the current research work was performed to determine and compare the chemical compositions of the EOs extracted from three different species of Artemisia (absinthium, sieberi, and scoparia) growing in Saudi Arabia and to test their antimicrobial potential against different bacterial and fungal strains. The EOs were isolated by hydro-distillation and analyzed by combining a gas chromatography–flame ionization detector (GC–FID) with the gas chromatography–mass spectroscopy (GC–MS) technique. Chemical analysis revealed that the three species had four compounds in common, i.e., limonene, camphor, terpinen-4-ol, and ethyl 2-methylbutyrate, while the main components identified in the EOs of A. absinthium and A. sieberi were cis-davanone (34.7% and 36.1%, respectively) and camphor (16.2% and 24.1%, respectively). In contrast, the keto compounds dominated in the oil of A. scoparia with 2-nonanone (55%) and 2-undecanone (24.5%) representing more than 80% of the total oil content. In addition, the antimicrobial activity of the isolated oils was evaluated by the broth microdilution method, revealing that all the EOs isolated from the examined Artemisia species displayed growth inhibiting actions in a concentration-dependent manner on selected tested microorganism species. The findings of the study also suggested that the tested EOs could be used to develop effective natural antimicrobial remedies with potential application in the fields of cosmetic industry, food manufacturing and medicine.     

Marine sterols—II : Asterosterol,a new C26 sterol from Asterias amurensis lütken

Asterosterol, a new marine C₂₆ sterol, was isolated from the asteroid, A. amurensis, and its structure was characterized as 22-trans-24-nor-5α-cholesta-7,22-dien-3β-ol (1). Episterol (9), 22-trans-(24R)-24-methylcholesta-7,22-dien-3β-ol (stellasterol, 3) and 22-trans-cholesta-7,22-dien-3β-ol (7) were also isolated and their structures were confirmed.     

Simple synthesis of sex pheromones of codling moth and red bollworm moth by the coupling of Grignard reagents with allylic halides

The coupling of Grignard reagents with allylic halides was employed for the synthesis of diolefinic pheromones of the codling moth (dodeca-8-trans, 10-trans-dien-1-ol, 1) and the red bollworm moth (dodeca-9-trans, 11-dien-1-yl acetate, 8).     

Alkylation of benzyl,cyclopropylmethyl and allyl acetates with trialkylaluminum. A stereochemical study

The title reaction is found synthetically useful and the stereochemical sudy has revealed that carbocationic intermediates are involved in the reaction of endo-2-acetoxy-norcarane, its epimer, and acetates of cis- and trans-carveol with trimethylaluminum.     

Dithiophosphorylation of nerol and geraniol trimethylsilyl derivatives

Reaction of tetraphosphorus decasulfide with О-(cis- and trans-3,7-dimethylocta-2,6-dien-1-yl)-trimethylsilanes affords О,О-bis(cis- and trans-3,7-dimethylocta-2,6-dien-1-yl) S-(trimethylsilyl)dithiophosphates.     

Hydrogénolyse en phase liquide sur Pd/C des époxydes du carvomenthène et du limonène

Hydrogenolysis over Pd/C of cis and trans epoxides of carvomenthene and limonene give a mixture of hydrocarbons, secondary and tertiary alcohols, and ketones in proportions dependent upon the nature of the starting material. In the limonene epoxides, the extracyclic double bond plays an important role in the opening of the oxirane ring through a common unsaturated tertiary alcohol intermediate by double bond migration, hydrogenation of which leads to the products. For the carvomenthene epoxides the results are similar to those found in the 4-t-butyl series with competition between cis addition and trans addition of hydrogen. The presence of the isopropenyl group leads to slower reaction rates in comparison with t-butyl analogues.     

Composition,Anti-MRSA Activity and Toxicity of Essential Oils from Cymbopogon Species

Many of the essential oils obtained from medicinal plants possess proven antimicrobial activity and are suitable for medicinal purposes and applications in the food industry. The aim of the present work was the chemical analysis of 19 essential oils (EOs) from seven different Cymbopogon species (C. nardus, C. citratus, C winterianus, C. flexuosus, C. schoenanthus, C. martinii, C. giganteus). Five different chemotypes were established by GC/MS and TLC assay. The EOs, as well as some reference compounds, i.e., citronellol, geraniol and citral (neral + geranial), were also tested for their antimicrobial and antibiofilm activity against methicillin-resistant Staphylococcus aureus (MRSA) by the microdilution method and direct bioautography. The toxicity of EOs was evaluated by Danio rerio ‘Zebrafish’ model assay. All examined EOs showed moderate to high activity against MRSA, with the highest activity noted for C. flexuosus—lemongrass essential oil, both in microdilution and direct autobiography method. Significant difference in the toxicity of the examined EOs was also detected.     

A study of some molecularly imprinted polymers as protic catalysts for the isomerisation of α-pinene oxide to trans-carveol

A range of acidic Molecularly Imprinted Polymers (MIPs) were synthesised using the imprint molecule trans-carvyl amine as a transition state analogue for the selective isomerisation of α-pinene oxide to trans-carveol. The amine functionality of the imprint molecule was used to selectively position a sulfonic acid group in the MIP binding pocket utilising 4-styrene sulfonic acid as the functional monomer. Co-polymerisation with varying ratios of styrene and divinylbenzene afforded a range of MIPs which were tested for their ability to effect selective formation of trans-carveol from α-pinene oxide. Although successful imprinting was demonstrated in binding studies, it was shown that solvent effects were dominant in effecting selective formation of trans-carveol. Using DMF as solvent, up to 70% of the products from acid catalysed isomerisation of α-pinene oxide with the polystyrene MIPs were obtained via the necessary para menthyl tertiary carbocation, and industrially important trans-carveol was obtained in 45% yield.     

The Inhibition of Non-albicans Candida Species and Uncommon Yeast Pathogens by Selected Essential Oils and Their Major Compounds

The epidemiology of yeast infections and resistance to available antifungal drugs are rapidly increasing, and non-albicans Candida species and rare yeast species are increasingly emerging as major opportunistic pathogens. In order to identify new strategies to counter the threat of antimicrobial resistant microorganisms, essential oils (EOs) have become an important potential in the treatment of fungal infections. EOs and their bioactive pure compounds have been found to exhibit a wide range of remarkable biological activities. We investigated the in vitro antifungal activity of nine commercial EOs such as Thymus vulgaris (thyme red), Origanum vulgare (oregano), Lavandula vera (lavender), Pinus sylvestris (pine), Foeniculum vulgare (fennel), Melissa officinalis (lemon balm), Salvia officinalis (sage), Eugenia caryophyllata (clove) and Pelargonium asperum (geranium), and some of their main components (α-pinene, carvacrol, citronellal, eugenol, γ-terpinene, linalool, linalylacetate, terpinen-4-ol, thymol) against non-albicans Candida strains and uncommon yeasts. The EOs were analyzed by GC-MS, and their antifungal properties were evaluated by minimum inhibitory concentration and minimum fungicidal concentration parameters, in accordance with CLSI guidelines, with some modifications for EOs. Pine exhibited strong antifungal activity against the selected non-albicans Candida isolates and uncommon yeasts. In addition, lemon balm EOs and α-pinene exhibited strong antifungal activity against the selected non-albicans Candida yeasts. Thymol inhibited the growth of all uncommon yeasts. These data showed a promising potential application of EOs as natural adjuvant for management of infections by emerging non-albicans Candida species and uncommon pathogenic yeasts.     

A Chemical Study of Burley Tobacco Flavour (Nicotiana tabacum L.) VII. Identification and synthesis of twelve irregular terpenoids,related to solanone,including 7,8-dioxabicyclo[3.2.1]octane and 4,9-dioxabicyclo[3.3.1]nonane derivatives

Twelve novel constituents isolated from Burley tobacco condensate by semi-preparative GLC. have been identified as (E)-3,4-epoxy-5-isopropyl-nonane-2,8-dione ( A ), exo-(1-methyl-4-isopropyl-7,8-dioxabicyclo[3.2.1]oct-6-yl)methyl ketone ( B ), exo-1-(1-methyl-4-isopropyl-7,8-dioxabicyclo[3.2.1]oct-6-yl)-ethanol ( C ), (E)-5-isopropyl-8-hydroxy-8-methyl-non-6-en-2-one ( D ), (E)-5-isopropyl-6,7-epoxy-8-hydroxy-8-methyl-nonan-2-one ( E ), endo-2-(1-methyl-4-isopropyl-7,8-dioxabicyclo[3.2.1]oct-6-yl)-propan-2-ol ( F ), 3,3,5-trimethyl-8-isopropyl-4,9-dioxabicyclo[3.3.1]nonan-2-ol ( G ), (E)-5-isopropyl-non-3-ene-2,8-diol ( H ), 5-isopropyl-nonane-2,8-diol ( I ), (E)-5-isopropyl-8-hydroxy-non-6-en-2-one ( J ), 5-isopropyl-8-hydroxy-nonan-2-one ( K ), and (E)-3-isopropyl-6-methyl-hepta-4,6-dien-1-ol ( L ). Compounds A–K were synthesized from norsolanadione ( 2 ), and compound L from 2-isopropyl-5-oxo-hexanal ( 15 ). The relative configuration of the bicyclic internal acetals B, C, F, G and their δ-keto-epoxide precursors A and E is discussed. All these Burley tobacco flavour components belong to a growing family of metabolites structurally related to solanone ( 1 ). They are believed to arise from the breakdown of cembrene-type precursors.     

Hydrogen bonding in cis and trans 1-t butylcyclohexan-4-ol

The homogeneous autoassociation of cis and trans 1-t-butylcyclohexan-4-ol has been investigated by means of IR spectroscopy. The temperature and concentration dependences of this interaction have been examined in CCl₄ as solvent. The results demonstrate a lower degree of association in the case of the cis compound, especially because of the steric hindrance of the acceptor function of this substance. The enthalpy of associatio-n-ΔH is found at about 13 [kJ/mole] for the trans compound and may be somewhat lower for the cis alcohol. The absorbance of the associated OH band of the trans compound is constant with varying concentration and/or temperature, but for the cis alcohol it increases with increasing concentration and decreasing temperature.     

Degradation and cis-to-trans isomerization of poly[(2,4-difluorophenyl)acetylene]s of various initial molecular weight: SEC,NMR, DLS and EPR study

Molecular weight (MW) and configurational stabilities of a series of high-cis poly[(2,4-difluorophenyl)acetylene]s (PdFPhA, M_w from 2.2 × 10⁴ to 9.7 × 10⁵) exposed to the atmosphere and diffuse daylight are reported. Polymers dissolved in THF-d₈ undergo simultaneous cis-to-trans isomerization and degradation under formation of a bimodal MW distribution. Degradation and isomerization rates are tightly connected and decrease with decreasing MW of the parent PdFPhAs. This finding may be interesting for the functional applications of substituted polyacetylenes. The partly aged PdFPhAs contain two separable fractions: higher-MW high-cis macromolecules containing a low amount of unpaired electrons and lower-MW deeply isomerized cis/trans macromolecules enriched in the unpaired electrons content. The difference in MW of these fractions reflects the various degradation rates of isomerized and high-cis macromolecules. Only a slow degradation without changes in the configurational structure proceeds if PdFPhA is allowed to age in the solid state. The suppression of the cis-to-trans isomerization reflects the suppression of motion of the polymer chains segments in the solid state.     

Phytochemical Variability of Essential Oils of Two Balkan Endemic Species: Satureja pilosa Velen. and S. kitaibelii Wierzb. ex Heuff. (Lamiaceae)

Satureja pilosa and S. kitaibelii (Lamiaceae) are Balkan endemic plant species, and the composition of their essential oil (EO) is highly variable. The aim of the present study was to establish: (1) the EO variability in two populations of S. pilosa (the intrapopulation), and (2) the EO variation in S. kitaibelii between nine populations (interpopulation) from Bulgaria and two from Serbia. The EOs of two Satureja species were obtained from aboveground plant parts by hydrodistillation and were analyzed by GC/MS/FID. Overall, the EO yield on the intrapopulation level of S. pilosa varied from 0.54% to 2.15%, while the EO of S. kitaibelii varied from 0.04% to 0.43% (interpopulation). The EO of S. pilosa was found to contain thymol and carvacrol as the main constituents, with other major constituents being p-cymene and γ-terpinene. S. pilosa samples in both studied populations formed six chemical groups. The major constituents (p-cymene, terpinen-4-ol, bornyl acetate, γ-muurolene, endo-borneol, cis-β-ocimene, trans-β-ocimene, carvacrol, α-pinene, thymoquinone, geranial, geranyl acetate, spathulenol, and caryophyllene oxide) of S. kitaibelii EO were considered for grouping the populations into ten chemotypes. The present study is the first report on the interpopulation diversity of S. kitaibelii EOs in Bulgaria. It demonstrated variability of the EOs between and within the populations of S. kitaibelii from Bulgaria. This study identified promising genetic material that could be further propagated and developed into cultivars for commercial production of S. kitaibelii and S. pilosa, thereby reducing the impact of collection on wild populations.     

Synthesis and structure of 1-(buta-1,3-dien-2-yl)pyrazoles and their behavior in Diels-Alder reactions

A convenient procedure has been developed for the synthesis of cis-and trans-isomeric 1-(buta-1,3-dien-1-yl)-1H-pyrazoles by reaction of the corresponding pyrazoles with β-methylacrolein diethyl acetal and subsequent 1,4-cleavage of the nucleophilic substitution products. The behavior of the title compounds in Diels-Alder reactions with maleic anhydride has been studied. According to the ¹H NMR data, 1-(buta-1,3-dien-1-yl)-1H-pyrazole is a mixture of cis and trans isomers. Butadienylpyrazoles having methyl groups in the pyrazole ring do not react with maleic anhydride.     

A new access to β-methyl substituted secondary alcohols. Application to the synthesis of 4-methylheptan-3-ol

All four stereoisomers of 4-methylheptan-3-ol were synthesized by a five-step route starting from 4-thianones. Key steps in the synthesis include: (a) reduction of 3-propyl-4-thianone to yield an easily separable isomeric mixture of cis- and trans-3-propyl-4-thianols; and (b) a highly efficient resolution of the particular cis/trans-isomers through a chromatographic separation of their respective esters with (S)-chlorofluoroacetic acid. Subsequent hydrolysis and desulfurization gave the required compounds in 18% overall yield. All the stereoisomers are obtained with purities better than 90%.