Simeon Popov

Bulgarian Academy of Sciences, Ulpia Serdica, Sofia-Capital, Bulgaria

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Publications (117)214.76 Total impact

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    ABSTRACT: Four grapevine seedlings were propagated and planted both in a greenhouse and in an experimental field. Surface components of their fresh leaves were easily obtained and analysed by gas chromatography-mass spectrometry. In total, 21 surface metabolites were identified. Unlike the greenhouse samples, the field ones possessed semiochemicals and compounds contributing to their survival under environmental stress. This study shows that the leaf surface of the grapevine possesses compounds indicating the conditions of breeding.
    Full-text · Article · Jul 2010 · Natural product research
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    ABSTRACT: The surface metabolic composition of berries, collected from the Bulgarian grapevine variety Storgozia, and 12 of its seedlings were studied by GC/MS. Diverse surface metabolites were identified. The main components were long chain n-alkanes, terpenoids, and esterified long-chain fatty acids. Amongst them, the terpenoids were most abundant, including, as are typical for plants, sesquiterpenoids, diterpenoids and triterpenoids. Cyperene, a sesquiterpene hydrocarbon, was identified for the first time in grapes. This compound and most of the other identified metabolites are known to possess biological functions that most probably contribute to the quality of grape berries and their defences against biotic and abiotic stressors.
    Full-text · Article · Jun 2010 · Natural product research
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    ABSTRACT: Cell suspension cultures of Lavandula vera (Lamiaceae), Nicotiana tabacum (Solanaceae), and Helianthus annuus (Asteraceae) were cultivated in three different ways: in shake flasks both as free suspensions and in two-phase systems (in the presence of Amberlite XAD-4 resin as a second phase), as well as in 3-L stirred tank reactor, and their volatile metabolic profiles were studied using GC-MS. A number of compounds, some of them having allelochemical and biological activities, were identified in all the three cell suspension cultures under study. Also the presence of some compounds, unusual for the intact plants, was observed. It was found that the cultivation mode strongly influences the production and the transport (secretion into the culture medium) of the low-molecular-mass volatile metabolites. Principal component analyses of 12 common hydrocarbons showed discrimination between the different cultivation modes (shake flasks and two-phase systems cultivation) by first principal component (PC1) and second principal component (PC2).
    Full-text · Article · Feb 2010 · Engineering in Life Sciences
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    ABSTRACT: Gas-phase tautomerism in 1-phenylazonaphthalene-4-ol (1) was studied by using electron ionization (EI) mass spectrometry on the basis of the fragmentations of the model enol and keto tautomers, where the movable proton is replaced by a methyl group. These fixed tautomers were obtained as an easy separable mixture by simple methylation of the cheap and easily accessible diazene (1). It was found that their EI mass spectral fragmentations are in full congruence with the already published theoretical predictions. The relative energies required for bond cleavage in 1 and its fixed tautomers were estimated by stepwise increasing of the electron energy of the ion source of the mass spectrometer. A simple equation for the approximate estimation of the molar fractions of the individual tautomers was suggested. It was shown that the enol form is dominant in the temperature range of 200-300 degrees C.
    Full-text · Article · Jun 2009 · Rapid Communications in Mass Spectrometry
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    ABSTRACT: Four groups of metabolites from the halophyte plant Stachys maritima Gouan, family Lamiaceae, were investigated: lipids, sterols, volatiles and polar compounds. Most of the metabolites have been previously reported to possess biological activity. Two of the main substances in the volatile fraction--phenidone and naphthalene, unusual for plants--were products of environmental contamination. This is a typical example of how marine pollutants could transfer and threaten terrestrial organisms via the trophic chain. The n-butanol extract possessed a relatively high antibacterial activity against S. aureus and Candida albicans, but was not active against Escherichia coli.
    No preview · Article · Feb 2009 · Natural product research
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    ABSTRACT: Chloroform extracts, n-butanol extracts, water extracts, and volatile compounds from seven species belonging to six Black Sea genera of brown algae and 10 species belonging to seven Black Sea genera of red algae were assessed for antibacterial, antiviral, and cytotoxic prop-erties. Most of the extracts showed pronounced effects against the Gram (q) bacterium Staphylococcus aureus. Activity towards the Gram (-) bacterium Escherichia coli was found in only few cases. A significant reduction in replication of influenza and Herpes simplex viruses in cell cultures was observed. Cytotoxic effect was established in a significant proportion of the algae investigated. The biological activities may be attributed to the presence of volatile compounds, some phenols, free fatty acids and their oxidized derivatives, eucalyptol, the methyl ester of phenyl acetic acid, and 1,2-dihydroxy ethane sulfonate.
    Full-text · Article · Feb 2009 · Botanica Marina
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    ABSTRACT: The main problem in the quantitative analysis of tautomeric compounds is that the individual tautomers cannot be physically separated. As a result, quantitative analysis, which requires calibration, is in general impossible. This is a general problem for molecular spectroscopy and gives rise to many chemometric approaches for the treatment of existing spectral data, all of them developed to overcome the lack of individual spectral data for the pure, individual, tautomers. The reliability of these approaches depends strongly on the mathematical and spectral approximations used. Therefore the aim of the current review is to describe and compare critically the most frequently used methods for the processing of spectral data of tautomeric systems. Such data are usually obtained by absorption spectroscopy (UV-Vis, Fl and sometimes IR) and NMR in solution, but, in addition, some attempts for quantitative analysis in gas phase by mass spectrometry are considered.
    Full-text · Article · Jan 2009 · Current Organic Chemistry
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    ABSTRACT: Surface leaf metabolites of two seedlings of a Bulgarian winemaking cultivar Storgozia I(1) were analyzed in two seasons - summer (July) and autumn (October). The resistance towards some fungal pathogens of one of the plants was estimated as superior to the resistance of the other one. Significant seasonal variations in the chemical constituents of the two seedlings were observed. The main metabolites of the summer samples were sterols, terpenes, fatty acids and heterocyclic compounds. In autumn, sterol and fatty acid contents decreased, mono- and diterpenes and heterocyclic compounds disappeared and instead of them hydrocarbons and alcohols were detected. Some individual components - stearic acid, alpha-amyrin, lupeol and squalene - correlated with the estimated resistance and were therefore proposed as biomarkers for the fungal resistance in grape-vine leaves.
    No preview · Article · Feb 2008 · Natural product research
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    ABSTRACT: From a biologically active fraction of extract from the fungus Fomitopsis pinicola, a new lanostane triterpene was isolated, 3alpha-acetyloxylanosta-8,24-diene-21-ol (1), along with two known triterpenic acids, (2) and (3). The structures of the compounds were elucidated based on their spectral properties. [structure: see text]
    No preview · Article · Jun 2007 · Natural product research
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    ABSTRACT: The compositions of the volatile and polar fractions from two coexisting Black Sea invertebrates, the mussel Mytilus galloprovincialis and the beadlet anemone Actinia equina, were established. The main metabolites in the volatile fraction from the investigated animals appeared to be methyl esters of fatty acids and fatty aldehydes. In the polar fraction from both animals low concentrations of free acids and nitrogen-containing compounds were obtained. Free carbohydrates were in much higher concentrations in M. galloprovincialis than in A. equina. Some sterols, probably as polar conjugates, were identified mainly in A. equina. Significant changes among all compounds appeared after treatment of both invertebrates with two different concentrations of cobalt ions. The variety of changes in each invertebrate could be due to their different evolutionary status. The effect of cobalt ions was often stronger at medium cobalt-ion concentrations.
    No preview · Article · May 2007 · Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology
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    ABSTRACT: Mushrooms in the genus Agaricus have worldwide distribution and include the economically important species A. bisporus. Some Agaricus species are inedible, including A. placomyces and A. pseudopratensis, which are similar in appearance to certain edible species, yet are known to possess unpleasant odours and induce gastrointestinal problems if consumed. We have studied the chemical composition of these mushrooms using GC-MS. Our GC-MS studies on the volatile fractions and butanol extracts resulted in the identification of 44 and 34 compounds for A. placomyces and A. pseudopratensis, respectively, including fatty acids and their esters, amino acids, and sugar alcohols. The most abundant constituent in the volatiles and butanol were phenol and urea respectively. We also identified the presence of ergosterol and two Delta7-sterols. In addition, 5alpha,8alpha-Epidioxi-24(xi)-methylcholesta-6,22-diene-3beta-ol was isolated for the first time from both mushrooms. Our study is therefore the first report on the chemical composition of these two species. The results obtained contribute to the knowledge of the chemical composition of mushrooms belonging to the Agaricus genus, and provide some explanation for the reported mild toxicity of A. placomyces and A. pseudopratensis, a phenonomenon that can be explained by a high phenol content, similar to that found in other Xanthodermatei species.
    Full-text · Article · Feb 2007 · Chemistry Central Journal
  • Jordan Nechev · Kamen Stefanov · Simeon Popov
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    ABSTRACT: The lipid and sterol fractions of the mussel Mytilus galloprovincialis and the anemone Actinia equina were analyzed before and after incubation with cobalt ions. There were significant changes in the lipid and sterol composition, strongly depending on the cobalt ions concentrations. The changes in the lipid composition of both invertebrates were different for neutral lipids and phospholipids. These changes concern the length of the fatty acid chains as well as their unsaturation. The cobalt ions inhibited the oxidation of sterols and their alkylation at C-24. Because of these results we can assume that some of the changes caused by cobalt ions might possess adaptive value.
    No preview · Article · Jun 2006 · Comparative Biochemistry and Physiology - Part A Molecular & Integrative Physiology
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    ABSTRACT: The polar compounds from six Black Sea red algae and six Black Sea brown algae were obtained by extraction of the defatted total extracts with n-butanol, silylated and investigated by GC/MS. Mainly acids, polyols, and sugars were found. The results obtained were compared with recent data for the composition of the polar components of other Black Sea red algae. Some conclusions about the chemotaxonomy of the species investigated were proposed. The red and brown algae showed specific differences in the metabolism of the polar compounds. The known functions of some of the polar compounds are discussed.
    Full-text · Article · Mar 2006 · Algological studies
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    ABSTRACT: The sterol composition of five Black Sea red algae: Callithamnion granulatum, Ceramium rubrum, Ceramium elegans, Laurencia papillosa and Laurencia coronopus was obtained. Monohydroxy sterols and their oxidized derivatives have been identified. The results obtained were compared with some recent data for the composition of sterols in other Black Sea red algae, which occupy different evolutionary positions. On the basis of their composition, some conclusions about the chemotaxonomy and chemoevolution of the species investigated have been proposed.
    Full-text · Article · Mar 2006 · Natural Product Research
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    ABSTRACT: Volatile compounds from the Black Sea red algae Bangia fuscopurpurea, Gelidium latifolium, Callithamnion granu-latum, Ceramium elegans, Laurencia papillosa and Laurencia coronopus were obtained by distillation-extraction and analysed by GC/MS. Different groups of compounds were identified: hydrocarbons, alkylated benzenes, alcohols, phenols, aldehydes, ketones, acids, esters, ter-penes, nitrogen-and halogen-containing compounds. The results are compared with some recent data for the composition of the volatile compounds from four previously investigated Black Sea red algae, which are at dif-ferent evolutionary stages. On the basis of their qualitative and semi-quantitative composition some che-motaxonomic conclusions are proposed. The eventual functions of some of the volatile compounds are briefly discussed.
    Full-text · Article · Jan 2006 · Botanica Marina
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    ABSTRACT: Polar and unpolar extracts from 18 species of the most widespread Bulgarian higher Basidiomycetes were tested for their activity against Staphylococcus aureus, Escherichia coli, and Candida albicans. Most of the studied extracts demonstrated activity against S. aureus but all were inactive against the Gram-negative E. coli and C. albicans. In general, the chloroform extracts were more active than the butanol ones. The most active mushroom extracts were comparable and even more active than standardized propolis extract in their inhibition of S. aureus. The study demonstrates the potential of mushrooms as antibacterial remedies and as a source of antibacterial compounds and gives useful hints for a more detailed investigation of the most active species.
    No preview · Article · Jan 2006 · International Journal of Medicinal Mushrooms
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    ABSTRACT: The sterol and fatty acid composition of three Adriatic Sea sponges (Geodia cydonium and two unidentified Tedania sp.), collected at the same time and same place, was established. Twenty-four sterols and forty fatty acids were identified. The identical ecological conditions, including the diet, allowed us to apply the results obtained for taxonomical conclusions, based on the biodiversity of the investigated sponges. On the basis of the sterol composition they can be separated into two groups: Tedania and Geodia sponges. The sterol and fatty acid composition indicates that the two investigated Tedania samples might be different species or subspecies.
    Full-text · Article · Jan 2006 · Zeitschrift fur Naturforschung. C, Journal of biosciences
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    ABSTRACT: The volatiles from fresh flowers and leaves of Gentiana lutea L., Gentiana punctata L. (yellow Gentiana spp.) and Gentiana asclepiadea L. (Gentianaceae Juss.) were analyzed by GC/MS and 81 compounds identified. The samples studied showed differences in the volatile profiles of flowers and leaves among the species. In the flower-oils straight chain saturated aliphatic hydrocarbons were dominant along with low concentrations of branched saturated aliphatic hydrocarbons and alkylated benzenes. These compounds were not present in the flowers of G. lutea and G. punctata and in the leaves of G. lutea. The branched saturated aliphatic hydrocarbons were the main constituents of the leaf-oil from G. ascleapidea. Terpenes were found in all flower-oils and in the leaf oil from G. punctata. Some of the identified compounds might have allelopathic activity. The results obtained confirm the accepted taxonomical scheme of the genus Gentiana and are also in agreement with the evolutionary less advanced position of the yellow species of Gentiana.
    No preview · Article · Sep 2005 · Biochemical Systematics and Ecology
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    ABSTRACT: Studies were conducted on low molecular metabolites (volatiles and polar compounds) produced by Rosa damascena Mill 1803 cell suspension culture, cultivated under different regimes: as a free suspension (in flasks and in bioreactor) and in a two-phase system (in the presence of Amberlite XAD-4 as a second phase). It was established that the main groups of volatiles were hydrocarbons and free acids and their esters and only traces of terpenoids were found. The main components of polar fraction were free acids, especially amino acids and oxidized acids. Depending on the culture conditions, significant differences were established in the amounts of all compounds under study in biomasses, culture media and adsorbed on the second phase (Amberlite XAD-4).
    No preview · Article · Aug 2005 · Journal of Biotechnology
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    ABSTRACT: This paper shows the changes of the volatile compounds from four Astragalus species at three phenological stages: leaf development, flowering and fructification, which might be connected with the plant defense. After GC/MS analyses of Astragalus glycyphyllos L., A. hamosus L., A. cicer L. and A. spruneri Boiss., different groups of volatile compounds were found: hydrocarbons, alcohols, aldehydes and ketones, esters, terpenes, chlorinated compounds, etc. Identified volatiles were used for a cluster analysis in order to make chemotaxonomic conclusions for these evolutionary different species.
    Full-text · Article · Jul 2005 · Zeitschrift fur Naturforschung C