Chemical Composition of Volatile and Extractive Components of Canary (Tenerife) Propolis

The vegetation of the Canary Islands is characterized by a large number of endemic species confined to different altitudinal levels. It can be assumed that these circumstances determine the characteristic features of the chemical composition of local beekeeping products, including propolis. We report, for the first time, the chemical composition of propolis from Tenerife (Canary Islands). The volatile emissions of three propolis samples collected from different apiaries are represented by 162 C1-C20 compounds, of which 144 were identified using the HS-SPME/GC-MS technique. The main group of volatiles, consisting of 72 compounds, is formed by terpenoids, which account for 42-68% of the total ion current (TIC) of the chromatograms. The next most numerous groups are formed by C6-C17 alkanes and alkenes (6-32% TIC) and aliphatic C3-C11 carbonyl compounds (7-20% TIC). The volatile emissions also contain C1-C6 aliphatic acids and C2-C8 alcohols, as well as their esters. Peaks of 138 organic C3-C34 compounds were recorded in the chromatograms of the ether extracts of the studied propolis. Terpene compounds form the most numerous group, but their number and content in different samples is within very wide limits (9-63% TIC), which is probably due to the origin of the samples from apiaries located at different altitudes. A peculiarity of the chemical composition of the extractive substances is the almost complete absence of phenylcarboxylic acids and flavonoids, characteristic of Apis mellifera propolis from different regions of Eurasia and North America. Aromatic compounds of propolis from Tenerife are represented by a group of nine isomeric furofuranoid lignans, as well as alkyl- and alkenyl-substituted derivatives of salicylic acid and resorcinol.

Characterization of Secondary Metabolites of Leaf Buds from Some Species and Hybrids of Populus by Gas Chromatography Coupled with Mass Detection and Two-Dimensional High-Performance Thin-Layer Chromatography Methods with Assessment of Their Antioxidant Activity

Poplars provide medicinal raw plant materials used in pharmacy. Leaf buds are one of the herbal medicinal products collected from poplars, having anti-inflammatory and antiseptic properties, but there are no quality standards for their production and there is a need to determine their botanical sources. Therefore, the chemical compositions of the leaf buds from four species and varieties of poplars, Populus balsamifera, P. × berolinensis, P. × canadensis 'Marilandica', and P. wilsonii were investigated and compared using gas chromatography coupled with mass detection (GC-MS) and two-dimensional high-performance thin-layer chromatography (2D-HPTLC) in order to search for taxa characterized by a high content of biologically active compounds and with a diverse chemical composition that determines their therapeutic effects. The presence of 163 compounds belonging to the groups of flavonoids, phenolic acids derivatives, glycerides, and sesquiterpenes was revealed. Moreover, the conditions for the separation and identification of biologically active compounds occurring in analyzed leaf buds using 2D-HPTLC were optimized and used for metabolomic profiling of the studied poplars, enabling their fast and simple botanical identification. The total phenolic (TPC) and flavonoid (TFC) contents of examined extracts were determined and their antioxidant capacities were estimated by spectrophotometric DPPH, ABTS, and FRAP assays. Based on the analysis of phytochemicals and antioxidant activity, P. × berolinensis buds were selected as the raw plant material for medicinal purposes with the highest content of active compounds and the strongest antioxidant activity.

Secondary metabolites of downy birch buds (Betula pubescens Erch.)

The subject of this study is the composition of low-molecular-weight metabolites in downy birch (Betula pubescens) buds and their participation in protection from various kinds of stress. Using the GC-MS, 640 compounds were detected, of which 314 were identified in downy birch buds for the first time. The volatile components detected using the SPME technique mainly consisted (about 70% of the total ionic current of the chromatogram, TIC) of mixtures of sesquiterpenoids. The exudate covering the buds, along with sesquiterpenoids (approximately 60% of TIC), included flavonoids (25% of TIC). The main part of the material extracted by supercritical carbon dioxide from buds comprised sesquiterpenoids and triterpenoids (47 and 28% of TIC, respectively). Via column chromatography, 25 known compounds (mainly flavonoids and triterpenoids) were isolated, most of which were first discovered in the buds of downy birch. Many compounds of these classes have strong biological activity and probably either directly or indirectly perform a protective function in birch buds. An assumption is made about the biological role of a number of secondary metabolites (such as volatile isomeric megastigmatriens and triterpene seco-acids) as well as about these compounds' possible means of biosynthesis, which were first discovered in the buds of downy birch.

Gas chromatographic-mass spectrometric determination of glycosides without prior hydrolysis

The article presents for the first time the linear temperature programmed retention indices on a column with stationary phases of 5% phenylpolydimethyl silicone and the mass spectra of trimethylsilyl (TMS) derivatives of 71 glycosides (both commercial preparations and compounds extracted from plant tissues) which were not characterized earlier by these parameters. Converted to their TMS derivatives, the glycosides were thermally stable: they exhibited single peaks on their chromatograms without products of thermal decomposition. Therefore this work demonstrates the suitability of high resolution-high temperature gas chromatography (HR-HT/GC) to analyse different groups of glycosides including compounds with disaccharide moieties without the necessity of their hydrolyses. Since a limited number of commercial and plant-isolated glycosides were available, an attempt was made to assess their retention indices using the known "structure-retention relationships" approach. It was demonstrated that the retention indices of silanised glycosides and their aglycones were characterized by a linear dependence.

Selective Behaviour of Honeybees in Acquiring European Propolis Plant Precursors

Honey bees harvest resins from various plant species and use them in the hive as propolis. While there have been a number of studies concerning the chemical composition of this antimicrobial product, little is known about selective behavior and bee preference when different potential plant sources of resin are available. The main objective of this paper was to investigate some aspects of behavioral patterns of honeybees in the context of resin acquisition. Samples of propolis originating from temperate zones of Europe and the supposed botanical precursors of the product were analyzed. Taxonomical markers of bud resins of two white birch species, aspen, black poplar, horse-chestnut, black alder, and Scots pine were determined through GC-MS analysis. All these trees have been reported as sources of propolis, but comparisons of the chemical composition of their bud resins with the compositions of propolis samples from seven European countries have demonstrated the presence of taxonomical markers only from black poplar, aspen, and one species of birch. This suggests selective behavior during the collection of bud resins by honeybees. To examine the causes of such selectivity, the antimicrobial properties of bud resins were determined. Horse-chestnut resins had lower antimicrobial activity than the other resins which did not differ significantly.

Chemical profile and antimicrobial activity of extractable compounds of Betula litwinowii (Betulaceae) buds

In spite of the long history of therapeutic use of buds from different birch species in folk medicine the existing information on their chemical composition is insufficient. The main goal was to develop a method for GC-MS determination of the chemical profile of birch buds as well as their antimicrobial activity. 150 substances of different classes were identified in Betula litwinowii buds. The volatile elements of the buds were mainly represented by sesquiterpene compounds. Ether extracts also contained other biologically active components such as flavonoids and triterpenoids. However, a particular feature of this fraction was the high content of sesquiterpene phenylpropenoids, including esters of ferulic and caffeic acids with caryophyllene-type alcohols that had not been previously found in any biological samples. Apart from carbohydrates, a series of free amino acids were detected in methanol extracts. The antimicrobial activity of the ether extracts of the buds was observed against all of the microorganisms tested, with MIC values from 0.04 to 0.08 mg mL-1 for Gram-positive bacteria and Candida albicans. However, their inhibitory activities against tested Gram-negative bacteria were rather occasional.

Rapid GC/MS determination of botanical precursors of Eurasian propolis

In this work, ether extracts of propolises from 11 countries of Europe and Asia together with extracts of the buds of their principal plant precursors were prepared and investigated by gas chromatography-mass spectrometry. For the first time, chemical compositions of the exudates of aspen, white birch and silver birch buds were determined. Basing on the data on the content of individual components and their groups, the method of rapid examination of plant precursors of propolis was developed. This new method is based on the use of a chromatogram for one extracted ion m/z=219, characteristic for a group of similar substances: phenylpropenoids. The I(T) retention indices of silylated derivatives of 449 substances registered in the buds of 6 species of trees and 37 samples of propolis extracts were calculated. These useful analytical parameters (majority of which are absent in the available databases) are attached in Supplementary information.

HS-SPME/GC-MS analysis of volatile and semi-volatile organic compounds emitted from municipal sewage sludge

The aim of the research involved identification and semi-quantitative determination of unknown volatile and semi-volatile organic compounds emitted to air by sewage sludge formed in the process of municipal wastewater treatment in a sewage treatment plant. Samples taken directly after completion of the technological process as well as the sludge stored on the premise of the sewage treatment plant were analyzed. A simple method using off-line headspace solid-phase microextraction combined with gas chromatography-mass spectrometry has been proposed for extraction and detection of organic pollutants. For reliable identification of compounds, combination of two independent parameters: mass spectra and linear temperature programmed retention indices were employed. Over 170 compounds of different structure were identified including aliphatic and aromatic hydrocarbons, alcohols, esters, carbonyls, as well as sulfur, nitrogen, and chlorine containing compounds. The prevailing substances included: ethyl ether, n-hexane, p-xylene, o-xylene, mesitylene, m-ethylbenzene, limonene, n-decane, n-undecane, and n-dodecane. A few compounds such as methanetiol, dimethyl polisulfide, octaatomic sulfur, phthalic anhydride, and indoles were identified in the sludge for the first time.

Gas chromatographic-mass spectrometric investigation of volatile and extractable compounds of crude royal jelly

Using headspace solid-phase microextraction (HS-SPME) followed by diethyl ether and methanol extraction, it was possible to isolate as many as 185 organic compounds out of 17 samples of crude royal jelly (RJ). Of the above compound number, 169 compounds were positively identified by means of gas chromatography-mass spectrometry. The volatile fraction of RJ consists of 25 different compounds where approximately 47% of the total ion current (TIC) of volatile compound chromatograms were composed of substances characterized by bactericidal (phenols) and repelling (octanoic acid and 2-heptanone) activities. Preliminary investigations have shown that RJ stored for 10 months at -18°C and 4°C keeps its composition of volatile compounds unchanged, however, at the same time at room temperature RJ phenol contents is decreased twice, whereas the fraction of aliphatic acids is increased 2.8 times due to the presence of both acetic and butyric acids. The chromatogram of RJ ether extracts showed 85 different compounds, however about 88% of TIC consisted exclusively of 8 compounds, i.e. 10-hydroxy-2-decenoic, 10-hydroxydecanoic, 3,10-dihydroxydecanoic, 8-hydroxyoctanoic, 2-decene-1,10-dioc and (Z)-9-hydroxy-2-decenoic acids. Nine aliphatic acids, which were detected for the first time, are the homologues of hydroxy- and oxo-acids identified earlier in RJ. In the RJ methanol extracts 82 compounds were identified, mainly carbohydrates and their derivatives. Approximately 87% of TIC consisted of fructose, glucose and sucrose. Special attention was paid to discrepancies between obtained and literature data concerning the presence of free amino acids in RJ. It was suggested that these inconsistencies can be explained by the differences in the methods of RJ collection and/or sample preparation.

Chemical composition and antimicrobial activity of essential oil of Bupleurum montanum and B. plantagineum

The hydrodistilled oils from the aerial parts of Bupleurum montanum and B. plantagineum, which are endemic to North Africa, including Algeria, were analyzed by gas chromatography-mass spectrometry (GC-MS). Ninety-eight compounds were detected in the oil of B. montanum, representing 98.6% of the total oil, and 68 in the oil of B. plantagineum, representing 99.8% of the total. Megastigma-4,6-(E),8(2)-triene was the major constituent of B. montana oil (25.3%). Other important compounds were myrcene, alpha-pinene and benzyl tiglate. Conversely, the major constituents of the oil of B. plantagineum were alpha-pinene (31.9%), cis-chrysanthenyl acetate (28.2%), and myrcene (24.8%), followed by the monoterpene hydrocarbon limonene (5.1%). The mutagenic, antiplasmodial and antimicrobial activities of the essential oils were individually evaluated against eleven microorganisms, using the agar diffusion method, by determination of MIC values. The investigated oils exhibited moderate antimicrobial activity. Maximum activity of the oils was observed against Nocardia asteroides, Staphylococcus aureus and Enterococcus faecalis. Fungicidal activity against Candida albicans was also found for both oils.

Chemical Composition and Antimicrobial Activity of Essential Oil of Bupleurum montanum and B. plantagineum

The hydrodistilled oils from the aerial parts of Bupleurum montanum and B. plantagineum, which are endemic to North Africa, including Algeria, were analyzed by gas chromatography-mass spectrometry (GC-MS). Ninety-eight compounds were detected in the oil of B. montanum, representing 98.6% of the total oil, and 68 in the oil of B. plantagineum, representing 99.8% of the total. Megastigma-4,6-(E),8(2)-triene was the major constituent of B. montana oil (25.3%). Other important compounds were myrcene, α-pinene and benzyl tiglate. Conversely, the major constituents of the oil of B. plantagineum were α-pinene (31.9%), cis-chrysanthenyl acetate (28.2%), and myrcene (24.8%), followed by the monoterpene hydrocarbon limonene (5.1%). The mutagenic, antiplasmodial and antimicrobial activities of the essential oils were individually evaluated against eleven microorganisms, using the agar diffusion method, by determination of MIC values. The investigated oils exhibited moderate antimicrobial activity. Maximum activity of the oils was observed against Nocardia asteroides, Staphylococcus aureus and Enterococcus faecalis. Fungicidal activity against Candida albicans was also found for both oils.

Gas chromatographic and mass spectrometric characterization of the organic acids extracted from some preparations containing lyophilized royal jelly

Thirty-five aliphatic acids were identified by gas chromatography-mass spectrometry from the ether extract of commercial preparations containing lyophilized royal jelly. The article presents linear-programmed retention indices on capillary columns with non-polar and low-polar stationary phases and mass spectra for identified compounds which were not characterized earlier by these parameters. Nine compounds are reported for the first time as royal jelly constituents.

Gas chromatographic investigation of phenylpropenoid glycerides from aspen (Populus tremula L.) buds

20 phenylpropenoid glycerides were synthesized by esterification of glycerol by p-coumaric, ferulic and caffeic acids. Main diagnostic ions in mass spectra and linear temperature programmed retention indices (LTPRI) of trimethylsilyl derivatives of these compounds were determined by GC/MS analysis. On the basis of these analytical parameters 39 in various degree substituted phenylpropenoid glycerides were for the first time identified in diethyl ether and ethyl acetate extracts from aspen buds.

Gas chromatographic retention indices of trimethylsilyl derivatives of mono- and diglycerides on capillary columns with non-polar stationary phases

Mono- and diglycerides play an important role in the metabolism of plants and animals. They are usually constitutive elements of complex mixtures and are not always as main components, which considerably hinder the identification of these analytes. This work communicates about a synthesis of a wide range of esters of glycerol and aliphatic C(6)-C(20) acids and presents gas chromatographic characteristics of 32 compounds in the form of the most reproducible parameters-linear-programmed retention indices on high-performance capillary columns with non-polar stationary phases. The article also presents mass spectra for a series of those glycerides which were not characterized earlier by these parameters.

Experimental determination and calculation of distribution coefficients between air and fiber with polydimethylsiloxane coating for some groups of organic compounds

This paper reports the results of experimental determination of distribution coefficients K(fa) for five terpene hydrocarbons and five aliphatic ketones between air and polydimethylsiloxane (PDMS) coating for solid-phase microextraction. To estimate the values of K(fa) for compounds of the same classes, which did not undergo experiments, it is proposed to use an empirical two-parameter equation in which various physicochemical and structural characteristics weakly correlated with each other are used as descriptors. It is also shown that for these purposes it is possible to use distribution coefficients of compounds in any other two-phase heterogeneous system, e.g. octanol-water or hexane-acetonitrile. This approach was applied to estimate K(fa) values of 92 volatile organic compounds.

GC Identification of Organic Compounds Based on Partition Coefficients of Their TMS Derivatives in a Hexane-Acetonitrile System and Retention Indices

This paper reports the experimentally determined and calculated partition coefficients (Kp) in a heterogeneous system consisting of two partially mixing organic solvents for trimethylsilyl derivatives of 119 compounds including phenols, phenolcarboxylic acids, mono- and dicarboxylic acids, and some carbohydrates and polyols. It was demonstrated that a simple model based on the available physico-chemical properties of molecules can be used to accurately predict the hexane-acetonitrile partition coefficients. Phenols, other organic acids, and carbohydrates form complex mixtures in extracts of plant tissues, in various biological fluids, as well as in waste waters. For group identification of these mixture components, it is desirable to use the parameterj which is a combination of Kp and gas chromatographic retention indices: j = kI - log Kp. This approach increases identification reliability in gas chromatographic analysis. The use of the group parameterj in the analysis of nonvolatile organic components of waste waters is reported.

GC-MS analysis of compounds extracted from buds of Populus balsamifera and Populus nigra

The composition of hexane and ether extracts from buds of two poplar species (Populus balsamifera and P. nigra) was investigated by GC-MS method. In hexane extracts, 54 "neutral" compounds were recorded. The greatest amounts of them are sesquiterpenes and n-alkanes. Among 56 components of ether extracts, many aliphatic acids and hydroxyacids were detected. However, the main fraction consists of phenolcarboxylic acids, substituted cinnamic acids, and their esters. It was established that chemotaxonomic differences between Populus balsamifera and P. nigra are observed in the case of both hexane and ether bud extracts.

Partition coefficients of alkyl aromatic hydrocarbons and esters in a hexane-acetonitrile system

Partition coefficients (Kp) in a heterogeneous system consisting of two immiscible organic solvents can be successfully used for a supplementary identification parameter in qualitative GC and GC-MS analysis of organic compounds. For rapid addition to database of Kp values, calculation methods based on the well-known 'retention-structure relationships' approach can be used. This paper reports the experimentally determined and calculated Kp values for 252 compounds including alkyl aromatic hydrocarbons and esters. It is shown that for group identification of components it is desirable to use not the Kp values themselves but the parameter j which is a combination of K, and gas chromatographic retention indices: j = kI - log Kp.

Gas chromatographic analysis of essential oils with preliminary partition of components

The efficiency of using combinations of retention indices and partition coefficients (Kp) with a hexane: acetonitrile system has been demonstrated by taking as an example the essential oil from Artemisia pallens Wall. Preliminary partition of the components between the two partly mixing liquids provides information by which components can be attributed to the appropriate homologous series. The use of group constants (j), which are functions of both partition coefficients and GC retention indices, in the practice of identifying the components of essential oils is reported for the first time.

Gas chromatographic-mass spectrometric determination of volatile organic compounds in an urban atmosphere

Polysorbimide and carbochrome, new sorbents with high temperature stability, have been used to concentrate trace amounts of atmospheric pollutants, and 136 C1-C13 organic compounds, including 126 hydrocarbons, 6 oxygen derivatives and 3 chlorides, were identified in air samples collected in the streets of Leningrad. One of the major features of the composition of the organic constituents of the urban air sampled is the presence of a number of CnH2n hydrocarbons (mainly olefins), and also CnH2n-2 and CnH2n-4 unsaturated hydrocarbons (including alpha-pinene and camphene). A comparison of the results with those of similar studies carried out on air samples from Zürich, Houston and Paris is of considerable interest in connection with the possible effect of geographical factors on the composition and lifetime of organic pollutants in the atmosphere.