Essential Oil and Glycosidically Bound Volatiles of Thymus pulegioides L. growing Wild in Croatia

The present paper represents the continuation of our research of free (essential oil) and glycosidically bound volatile compounds from Croatian wild-growing aromatic plants. The essential oil and glycosidically bound volatile compounds were isolated from the fresh and dried plant material of Thymus pulegioides L. at three stages of plant development and analysed by gas chromatography-mass spectrometry (GC-MS). The most abundant constituents in essential oils were geraniol and linalool followed by thymol, g-terpinene, thymol methyl ether, borneol and geranyl acetate, all of which showed quantitative variations during the plant development stages and whether fresh or dried plants were used for essential oil isolation. After enzymatic hydrolysis of glycosidic fractions, the GC-MS analysis of volatile aglycones revealed eugenol, geraniol and 1-octen-3-ol as the main aglycones in all samples. Other important aglycones were thymoquinone, 2-phenylethanol, 3-hexenol, 3-octanol, benzyl alcohol and linalool. Quantitative variations were observed when the aglycones were analysed at three different stages of plant development. Because of the high geraniol content in the essential oils and in the aglycone fractions this Thymus pulegioides L. could be interesting as a fragrant material for perfume industry or for food flavouring

The Essential Oil and Glycosidically Bound Volatile Compounds of Calamintha nepeta (L.) Savi

Results of the investigation of the essential oil and glycosidically bound volatile compounds of Calamintha nepeta (L.) Savi are presented in the paper. The essential oil was isolated by hydrodistillation and glycosides were extracted with ethyl acetate. The yield of essential oil was W = 0.91%. The essential oil was fractionated on a microcolumn with solvents of different polarity. One fraction of terpene hydrocarbons and four fractions of oxygenated terpene compounds were obtained. All fractions were analyzed by gas chromatography-mass spectrometry (GC-MS) on two columns with different polarity of the stationary phases. The purpose of the fractionation was to obtain a more completely analysis. In this way, sixtyfive compounds were identified. In contrast, only twenty-four compounds were identified in the essential oil without fractionation. The main components were piperitone oxide, piperitenone oxide, limonene, caryophyllene, thymol, linalool, 3-octanol and other compounds in smaller amounts. After isolation, final purification of the glycosides by »flash« chromatography on silicagel column and enzymatic hydrolysis, the liberated aglycones were analyzed in the same way as the essential oil fractions. The content of volatile aglycones was W = 0.00081% or 8.1 mg kg-1 of the plant material. Eighteen compounds were identified. The main aglycones were eugenol, carveol, 3-octanol, 3-hexene-1-ol, 2-butanol, 2-phenylethanol, methyl salicylate, benzyl alcohol, acetophenone derivates, and others. Some of the aglycones were the same or structurally similar to the essential oil components. Glycosidically bound volatiles in this plant have not been investigated so far

Volatile Compounds Identified in Traditional Croatian Cow’s and Goat’s Cheeses Matured in Lambskin Sack Determined by Gc-Ms Analysis

Cheeses ripened in animal skin sacks belong to traditional cheeses that are strongly connected to the culture and history of the country from which they originate. Their main specificity is anaerobic ripening in an animal skin sack. The aim of this study was to determine the volatile compounds of Croatian cheeses in a sack of lamb skin produced from either raw cow’s or goat’s milk and relate them to the aroma of these traditional cheeses. Volatile compounds were extracted by headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE) and analysed by gas chromatography-mass spectrometry (GC-MS). A total of 32 volatiles were identified in the cheese samples, including 12 carboxylic acids, 8 esters, 6 alcohols, 3 ketones, 2 hydrocarbons and 1 aldehyde. In the samples obtained by HS-SPME, the fatty acids and alcohols were the most abundant, while in the samples obtained by USE, the fatty acids were the most abundant

INHIBITION OF ALUMINIUM ALLOY CORROSION IN CHLORIDE SOLUTION BY CAFFEINE ISOLATED FROM BLACK TEA

Caffeine (1,3,7-trimethylxanthine) was isolated from black tea and characterised using different physical methods. The corrosion inhibition performance of the caffeine isolate (in concentration from 110-5 to 110-3 mol/dm3) on aluminium alloy corrosion in neutral 0.5 mol/dm3 NaCl solution was investigated using potentiodynamic and linear polarization measurements at 20 C. Corrosion potential, corrosion current and polarization resistance were determined and surface coverage of inhibitor molecules and inhibition efficiency were calculated. The obtained results show that caffeine effectively inhibited the corrosion reaction in the chloride solution with an inhibition efficiency of up to 76%. Furthermore, caffeine was found to function essentially as a mixed type with a higher influence on cathodic reaction. The adsorption behaviour of investigated inhibitor can be described by the Freundlich adsorption isotherm. The adsorption free energy closes to -10 kJ/mol indicates physical adsorption of the caffeine on the aluminium alloy surface in NaCl solution

The Essential Oil and Glycosidically Bound Volatile Compounds of Calamintha nepeta (L.) Savi

Results of the investigation of the essential oil and glycosidically bound volatile compounds of Calamintha nepeta (L.) Savi are presented in the paper. The essential oil was isolated by hydrodistillation and glycosides were extracted with ethyl acetate. The yield of essential oil was W = 0.91%. The essential oil was fractionated on a microcolumn with solvents of different polarity. One fraction of terpene hydrocarbons and four fractions of oxygenated terpene compounds were obtained. All fractions were analyzed by gas chromatography-mass spectrometry (GC-MS) on two columns with different polarity of the stationary phases. The purpose of the fractionation was to obtain a more completely analysis. In this way, sixtyfive compounds were identified. In contrast, only twenty-four compounds were identified in the essential oil without fractionation. The main components were piperitone oxide, piperitenone oxide, limonene, caryophyllene, thymol, linalool, 3-octanol and other compounds in smaller amounts. After isolation, final purification of the glycosides by »flash« chromatography on silicagel column and enzymatic hydrolysis, the liberated aglycones were analyzed in the same way as the essential oil fractions. The content of volatile aglycones was W = 0.00081% or 8.1 mg kg-1 of the plant material. Eighteen compounds were identified. The main aglycones were eugenol, carveol, 3-octanol, 3-hexene-1-ol, 2-butanol, 2-phenylethanol, methyl salicylate, benzyl alcohol, acetophenone derivates, and others. Some of the aglycones were the same or structurally similar to the essential oil components. Glycosidically bound volatiles in this plant have not been investigated so far

Free and Glycosidically Bound Volatile Compounds from Cypress Cones (Cupressus Sempervirens L.)

Isolations of glycosides from fresh cypres cones, Cupressus Sempervirens L. (Cupressaceae), were performed by cold and hot ethyl acetate extraction. After enzymatic hydrolysis by means of β-glucosidase, 18 aglycones were released. The glycosidically bound volatile compounds amounted to 7-8 mg kg-1. The main aglycones were 3-hydroxybenzoic acid methyl ester (15.5%) and thymoquinone (5-isopropyl-2-methyl-1,4-benzoquinone: 3.7-9.7%). Other important aglycones were perilla alcohol (3.6-8.2%), p-cymen-8-ol (5.3-6.4%), 2-phenylethanol (2.7-6.9%) and carvacrol (2.5-6.3%). There was no similarity between the glycosidically bound aglycones and the corresponding free compounds found in the essential oil

Primjena mikroekstrakcije vršnih para na čvrstoj fazi kao preparativni pristup za plinsku kromatografiju sa spektrometrijom masa

Reviewed in brief are the selected results of the application of headspace solid-phase microextraction as a preparative approach for gas chromatography – mass spectrometry (HS-SPME/GC-MS) for natural organic compounds research at the University of Split, Faculty of Chemistry and Technology. A wide variety of headspace compounds from different natural sources has been identified: lower aliphatic compounds (e.g., C5- and C6-compounds), aromatic compounds, monoterpenes (e.g., linalool derivatives (oxides, anhydro-oxides, epoxides), hotrienol), sesquiterpenes (e.g., eudesmol isomers, hydrocarbons), and C9- and C13-norisoprenoids (e.g., 3,4-dihydro-3-oxoedulan, 4-oxoisophorone, trans-β-damascenone). These compounds are important phytochemicals as flavour/fragrance compounds, chemical markers of the botanical origin or others (e.g., allelochemicals, pheromones, or acaricide residue). This work is licensed under a Creative Commons Attribution 4.0 International License.Ukratko su prikazani odabrani rezultati primjene mikroekstrakcije vršnih para na čvrstoj fazi kao preparativnog pristupa plinskoj kromatografiji – spektrometriji masa (HS-SPME/GC-MS) za istraživanje prirodnih spojeva, koje je provedeno na Kemijsko-tehnološkom fakultetu Sveučilištu u Splitu. Velika raznolikost spojeva vršnih para istražena je iz različitih prirodnih izvora: niži alifatski spojevi (npr. C5- i C6-spojevi), aromatski spojevi, monoterpeni (npr. derivati linaloola (oksidi, anhidro-oksidi, epoksidi), hotrienol), seskviterpeni (npr. eudezmol izomeri, ugljikovodici) te C9- i C13-norizoprenoidi (npr. 3,4-dihidro-3-oksoedulan, 4-oksoisoforon, trans-β-damascenon). Ti su spojevi važne fitokemikalije kao spojevi aroma/mirisa, kemijski marker botaničkog podrijetla ili drugo (npr. aleokemikalije, feromoni ili ostatci akaricida). Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna

Essential Oil and Glycosidically Bound Volatile Compounds from the Needles of Common Juniper (Juniperus communis L.)

The essential oil was isolated by hydrodistillation and glycosides were extracted with ethyl acetate from the needles of common juniper. The obtained essential oil was fractionated on microcolumn with solvents of different polarity. Ali fractions were analysed by gas chromatography-mass spectrometry (GC-MS) on two columns with different polarity of the stationary phases. Sixty-three compounds were identified. The main components of juniper needle oil were: α-pinene (16.9%), sabinene (12.1%), terpinene-4-ol (7.7%), β-phellandrene (7.3%), widdrene (6.4%), γ-terpinene (5.9%), β-terpinene (4.3%), α-terpinene (3.8%), and other compounds in smaller quantities. After isolation, final purification of the glycosides and enzymatic hydrolysis, the liberated aglycones were analysed in the same way as fractions of the essential oil. Twenty-two aglycones were identified. The main aglycones were: 3-phenyl-2-propen-1-ol, (32.8%), 2-phenylpropanol (6.0%), thymoquinone (4.6%), 3,4,5-trimethoxybenzaldehyde (4.3%), 3-methyl-2-buten-1-ol (2.8%), 2-phenylethanol (2.8%), 3-phenyl-2-propenal, (2.7%), methyl-3-hydroxybenzoate (2.6%), and p-cymen-8-ol, o-methoxybenzyl alcohol, methyl salycilate, α-methyl-benzyl alcohol, 1-octen-3-ol, and other compounds

BioProspecting of the Adriatic Sea: A Review of Recent Studies of Volatile Organic Compounds

Istraživanja predstavljena u ovom preglednom radu doprinose poznavanju isparljivih organskih spojeva iz morskih organizama, posebno iz makroalgi Jadranskog mora. Za izolaciju isparljivih spojeva iz svježih i/ili na zraku osušenih uzoraka primijenjene su komplementarne metode: mikroekstrakcija vršnih para na čvrstoj fazi (HS-SPME) i/ili hidrodestilacija (HD). Dobiveni izolati analizirani su vezanim sustavom plinske kromatografije-spektrometrije masa (GC-MS). U vršnim parama i isparljivim uljima makroalgi Halopteris filicina, Flabellia petiolata, Dictyota dichotoma, Taonia atomaria, Padina pavonica, Codium bursa i morskoj cvjetnici Posidonia oceanica pronađeno je mnoštvo različitih spojeva, uglavnom seskviterpena, diterpena i alifatskih spojeva. Alifatski spojevi male molekulske mase, poput dimetil-sulfida (DMS), tribrommetana, 1-jodpentana, 3-metilbut-2-enala, heksanala i pent-1-en-3-ona, nađeni su u kemijskim profilima vršnih para. Također su identificirani i alifatski C8- i C11-spojevi (npr. oktan-l-ol, oktanal, okt-1-en-3-ol, 6-metilhept-5-en-2-on, fukoseraten i diktioptereni). Zajedno s višim acikličkim ugljikovodicima, također pronađenim u vršnim parama (npr. heptadekan), u ispitivanim isparljivim uljima identificirani su i viši alifatski alkoholi (npr. (Z)-oktadec-9-en-1-ol, heksadekan-1-ol, (Z,Z)-oktadeka-3,13-dien-1-ol) i esteri (npr. diizooktil-ftalat, dibutil-ftalat). Fenilpropanski derivati (npr. benzaldehid, benzil-alkohol) i C13-norizporenoidi (npr. α-jonon i β-jonon) također su pronađeni u isparljivim profilima, kao i mnoštvo seskviterpena (npr. germakren D, biciklogermakren, δ-kadinen, epizonaren, epibicikloseskvifelandren, β-kubeben, gleenol, (E)-β-farnezen). Isparljivi organski spojevi identificirani u morskim algama mogu poslužiti u kemotaksonomskim istraživanjima. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.Studies presented in this review contribute to the knowledge of volatile organic compounds (VOCs) from marine organisms, especially macrolgae from the Adriatic Sea. Complementary methods were used for the isolation of VOCs from fresh and/or air-dried samples: headspace solid-phase microextraction (HS-SPME) and/or hydrodistillation (HD). The isolates were analysed by gas chromatography and mass spectrometry (GC-MS). A variety of different volatile compounds, mainly sesquiterpenes, diterpenes and aliphatic compounds were found in headspace and volatile oils of macroalgae Halopteris filicina, Flabellia petiolata, Dictyota dichotoma, Taonia atomaria, Padina pavonica, Codium bursa, and one seagrass Posidonia oceanica. Low molecular aliphatic compounds were found in the chemical profiles of headspace, such as dimethyl sulphide (DMS), tribromomethane, 1-iodopentane, 3-methylbut-2-enal, hexanal and pent-1-en-3-one. Aliphatic C8- and C11-compounds (e.g., octan-1-ol, octanal, oct-1-en-3-ol, 6-methylhept-5-en-2-on, fucoserratene and dictyopterenes) were also identified. Along with higher acyclic hydrocarbons, which are also found in headspace (e.g. heptadecane), in the investigated volatile oils higher aliphatics alcohols (e.g., (Z)-oktadec-9-en-1-ol, hexadecan-1-ol, (Z,Z)-oktadeca-3,13-dien-1-ol) and esters (e.g., diisooctyl phthalate, dibutyl phthalate) were found. Phenylpropane derivatives (e.g., benzaldehyde, benzyl alcohol) and C13-norisporenoids (e.g., α-ionone and β-ionone) were also identified in the volatile profiles, as well as an array of sesquiterpenes (e.g., germacrene D, bicyclogermacrene, δ-cadinene, epizonarene, epi-bicyclosesquiphellandrene, β-cubebene, gleenol, (E)-β-farnesene). VOCs, identified in marine algae, could be useful for chemotaxonomic studies. This work is licensed under a Creative Commons Attribution 4.0 International License

Volatile Constituents of Aerial Parts of Capsella rubella Reut.

Three different isolates from unexplored wild-growing Brassicaceae plant Capsella rubella were investigated in order to provide more complete insight of the composition and content of volatile constituents. The analysis of volatile compounds was performed by GC-FID/MS. C. rubella essential oil, that is isolate obtained by hydrodistillation, was characterized by a high percentage of 3,4-epithiobutanenitrile (67.8 %). The main volatile compounds in autolysate, i.e. isolate obtained by solvent extraction upon endogenous enzymatic hydrolysis, were 3,4-epithiobutanenitrile (44.1 %) and ethyl isothiocyanate (29.4 %). Same as in autolysate, the main volatile constituents of hydrolysate, i.e. isolate obtained by solvent extraction upon exogenous enzymatic hydrolysis, were 3,4-epithiobutanenitrile and ethyl isothiocyanate, but with ethyl isothiocyanate as the dominating compound (57.8 %) followed by 3,4-epithiobutanenitrile (15.6 %). The results showed that qualitative and quantitative composition of C. rubella volatile constituents depends on the isolation method. But, regardless of the isolation method sulfur- and nitrogen-containing volatile compounds were quantitatively dominating constituents in all isolates. This work is licensed under a Creative Commons Attribution 4.0 International License