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Efraim Lewinsohn - One of the best experts on this subject based on the ideXlab platform.

  • the inheritance of volatile phenylpropenes in bitter fennel foeniculum vulgare mill var vulgare apiaceae chemotypes and their distribution within the plant
    Biochemical Systematics and Ecology, 2009
    Co-Authors: Michal Gross, Yael Cohen, Yaakov Tadmor, Efraim Lewinsohn, Nativ Dudai, Einat Bar, Jacob Friedman
    Abstract:

    The volatile phenylpropenes Estragole and t-anethole are the major constituents of the oleoresin of the aerial parts of bitter fennel (Foeniculum vulgare Mill. var. vulgare, Apiaceae). The levels of Estragole and t-anethole varied during plant development, being maximal in flowers and developing mericarps. Still the ratio between Estragole and t-anethole remained constant throughout development. Estragole-rich types were hybridized with t-anethole rich types to examine the genetic basis of this polymorphism. A reverse correlation between Estragole and t-anethole content was evident and the action of a biallelic gene with partial dominance for high Estragole content was inferred. Understanding phenylpropene inheritance might explain chemical polymorphism in wild bitter fennel populations, sheds light on the molecular mechanisms that lead to chemotypes evolution and is crucial for breeding fennel varieties with desired chemical compositions.

  • Biosynthesis of Estragole and t-anethole in bitter fennel (Foeniculum vulgare Mill. var. vulgare) chemotypes. Changes in SAM:phenylpropene O-methyltransferase activities during development
    Plant Science, 2002
    Co-Authors: Michal Gross, Yael Cohen, Olga Larkov, Jacob Friedman, Uzi Ravid, Eli Putievsky, Nativ Dudai, Efraim Lewinsohn
    Abstract:

    Abstract Estragole and t-anethole are the major constituents of the essential oils of bitter fennel chemotypes (Foeniculum vulgare Mill. var. vulgare. Apiaceae). Cell-free extracts from bitter fennel tissues display O-methyltransferase activities able to in vitro methylate chavicol and t-anol to produce Estragole and t-anethole, respectively, by utilizing S-adenosyl- l -methionine as a methyl group donor. Analysis of different plant parts of an Estragole-rich chemotype, indicated an association between Estragole accumulation and chavicol O-methyltransferase activity during development. Young leaves displayed higher levels of O-methyltransferase activity than old leaves. In developing fruits O-methyltransferase activity levels increased until the wasty stage was reached and then dramatically decreased. This chemotype also displayed t-anol O-methyltransferase activity at higher levels than chavicol O-methyltransferase activity although these tissues accumulate mainly Estragole. O-methyltransferases activities extracted from a high-t-anethole fennel chemotype also methylated t-anol and chavicol at comparable rates. Thus, although the chemotypes greatly differ in their phenylpropenoids composition, both are efficient in in vitro forming t-anethole and Estragole.

  • Biosynthesis of Estragole and methyl-eugenol in sweet basil (Ocimum basilicum L). Developmental and chemotypic association of allylphenol O-methyltransferase activities
    Plant Science, 2000
    Co-Authors: Efraim Lewinsohn, Elena Lastochkin, David Chaimovitsh, Olga Larkov, Yaakov Tadmor, Uzi Ravid, Eli Putievsky, Nativ Dudai, Eran Pichersky
    Abstract:

    Sweet basil (Ocimum basilicum L., Lamiaceae) is a common herb, used for culinary and medicinal purposes. The essential oils of different sweet basil chemotypes contain various proportions of the allyl phenol derivatives Estragole (methyl chavicol), eugenol, and methyl eugenol, as well as the monoterpene alcohol linalool. To monitor the developmental regulation of Estragole biosynthesis in sweet basil, an enzymatic assay for S-adenosyl-L-methionine (SAM):chavicol O-methyltransferase activity was developed. Young leaves display high levels of chavicol O-methyltransferase activity, but the activity was negligible in older leaves, indicating that the O-methylation of chavicol primarily occurs early during leaf development. The O-methyltransferase activities detected in different sweet basil genotypes differed in their substrate specificities towards the methyl acceptor substrate. In the high-Estragole-containing chemotype R3, the O-methyltransferase activity was highly specific for chavicol, while eugenol was virtually not O-methylated. In contrast, chemotype 147:97, that contains equal levels of Estragole and methyl eugenol, displayed O-methyltransferase activities that accepted both chavicol and eugenol as substrates, generating Estragole and methyl eugenol, respectively. Chemotype SW that contains high levels of eugenol, but lacks both Estragole and methyl eugenol, had apparently no allylphenol dependent O-methyltransferase activities. These results indicate the presence of at least two types of allylphenol-specific O-methyltransferase activities in sweet basil chemotypes, one highly specific for chavicol; and a different one that can accept eugenol as a substrate. The relative availability and substrate specificities of these O-methyltransferase activities biochemically rationalizes the variation in the composition of the essential oils of these chemotypes. © 2000 Elsevier Science Ireland Ltd. All rights reserved.

  • Biosynthesis of Estragole and methyl-eugenol in sweet basil (Ocimum basilicum L). Developmental and chemotypic association of allylphenol O-methyltransferase activities
    Plant Science, 2000
    Co-Authors: Efraim Lewinsohn, Elena Lastochkin, David Chaimovitsh, Olga Larkov, Yaakov Tadmor, Uzi Ravid, Eli Putievsky, Nativ Dudai, Eran Pichersky
    Abstract:

    Sweet basil (Ocimum basilicum L., Lamiaceae) is a common herb, used for culinary and medicinal purposes. The essential oils of different sweet basil chemotypes contain various proportions of the allyl phenol derivatives Estragole (methyl chavicol), eugenol, and methyl eugenol, as well as the monoterpene alcohol linalool. To monitor the developmental regulation of Estragole biosynthesis in sweet basil, an enzymatic assay for S-adenosyl-L-methionine (SAM):chavicol O-methyltransferase activity was developed. Young leaves display high levels of chavicol O-methyltransferase activity, but the activity was negligible in older leaves, indicating that the O-methylation of chavicol primarily occurs early during leaf development. The O-methyltransferase activities detected in different sweet basil genotypes differed in their substrate specificities towards the methyl acceptor substrate. In the high-Estragole-containing chemotype R3, the O-methyltransferase activity was highly specific for chavicol, while eugenol was virtually not O-methylated. In contrast, chemotype 147:97, that contains equal levels of Estragole and methyl eugenol, displayed O-methyltransferase activities that accepted both chavicol and eugenol as substrates, generating Estragole and methyl eugenol, respectively. Chemotype SW that contains high levels of eugenol, but lacks both Estragole and methyl eugenol, had apparently no allylphenol dependent O-methyltransferase activities. These results indicate the presence of at least two types of allylphenol-specific O-methyltransferase activities in sweet basil chemotypes, one highly specific for chavicol; and a different one that can accept eugenol as a substrate. The relative availability and substrate specificities of these O-methyltransferase activities biochemically rationalizes the variation in the composition of the essential oils of these chemotypes. © 2000 Elsevier Science Ireland Ltd. All rights reserved.

  • Chemical variation among indigenous populations of Foeniculum vulgare var. vulgare in Israel.
    Planta Medica, 1999
    Co-Authors: O Barazani, Eli Putievsky, Efraim Lewinsohn, A Fait, Y Cohen, S Diminshtein, U Ravid, J Friedman
    Abstract:

    The composition of hexane extract constituents of ripe mericarps ("achenes") of eleven indigenous populations of Foeniculum vulgare var. vulgare (Apiaceae) was studied. Natural populations were selected along a gradient of annual rainfall from ca. 1000 mm in the northern region down to 125 mm in the Negev desert. Eighteen constituents, with Estragole, trans-anethole, fenchone, limonene and alpha-pinene as the major components were separated by GC-MS. Characterized by the level of Estragole and trans-anethole, four different groups were obtained: (1) highest Estragole (63%) and the lowest trans-ane-thole (3%) characterized the population of Mt. Meron; (2) estra-gole (39-47%) and trans-anethole (17-29%) in 3 mountainous populations; (3) Estragole (21-29%) and trans-anethole (38-49%) in the coastal and lowland populations; (4) two exceptional populations with the lowest content of Estragole (ca.8%) and high content of trans-anethole (55 and 74%). A reversed association between the content of Estragole and trans-anethole suggests a common precursor. In habitats with a high precipitation, the content of Estragole was high and that of trans-anethole was low, and vice versa under limited rainfall. It is proposed that the composition of oleoresins of F. vulgare var. vulgare could be governed by environmental conditions. Nevertheless, it is not ruled out that genetic variations account for the recorded differences.

Bilal Gürbüz - One of the best experts on this subject based on the ideXlab platform.

Eli Putievsky - One of the best experts on this subject based on the ideXlab platform.

  • Biosynthesis of Estragole and t-anethole in bitter fennel (Foeniculum vulgare Mill. var. vulgare) chemotypes. Changes in SAM:phenylpropene O-methyltransferase activities during development
    Plant Science, 2002
    Co-Authors: Michal Gross, Yael Cohen, Olga Larkov, Jacob Friedman, Uzi Ravid, Eli Putievsky, Nativ Dudai, Efraim Lewinsohn
    Abstract:

    Abstract Estragole and t-anethole are the major constituents of the essential oils of bitter fennel chemotypes (Foeniculum vulgare Mill. var. vulgare. Apiaceae). Cell-free extracts from bitter fennel tissues display O-methyltransferase activities able to in vitro methylate chavicol and t-anol to produce Estragole and t-anethole, respectively, by utilizing S-adenosyl- l -methionine as a methyl group donor. Analysis of different plant parts of an Estragole-rich chemotype, indicated an association between Estragole accumulation and chavicol O-methyltransferase activity during development. Young leaves displayed higher levels of O-methyltransferase activity than old leaves. In developing fruits O-methyltransferase activity levels increased until the wasty stage was reached and then dramatically decreased. This chemotype also displayed t-anol O-methyltransferase activity at higher levels than chavicol O-methyltransferase activity although these tissues accumulate mainly Estragole. O-methyltransferases activities extracted from a high-t-anethole fennel chemotype also methylated t-anol and chavicol at comparable rates. Thus, although the chemotypes greatly differ in their phenylpropenoids composition, both are efficient in in vitro forming t-anethole and Estragole.

  • Biosynthesis of Estragole and methyl-eugenol in sweet basil (Ocimum basilicum L). Developmental and chemotypic association of allylphenol O-methyltransferase activities
    Plant Science, 2000
    Co-Authors: Efraim Lewinsohn, Elena Lastochkin, David Chaimovitsh, Olga Larkov, Yaakov Tadmor, Uzi Ravid, Eli Putievsky, Nativ Dudai, Eran Pichersky
    Abstract:

    Sweet basil (Ocimum basilicum L., Lamiaceae) is a common herb, used for culinary and medicinal purposes. The essential oils of different sweet basil chemotypes contain various proportions of the allyl phenol derivatives Estragole (methyl chavicol), eugenol, and methyl eugenol, as well as the monoterpene alcohol linalool. To monitor the developmental regulation of Estragole biosynthesis in sweet basil, an enzymatic assay for S-adenosyl-L-methionine (SAM):chavicol O-methyltransferase activity was developed. Young leaves display high levels of chavicol O-methyltransferase activity, but the activity was negligible in older leaves, indicating that the O-methylation of chavicol primarily occurs early during leaf development. The O-methyltransferase activities detected in different sweet basil genotypes differed in their substrate specificities towards the methyl acceptor substrate. In the high-Estragole-containing chemotype R3, the O-methyltransferase activity was highly specific for chavicol, while eugenol was virtually not O-methylated. In contrast, chemotype 147:97, that contains equal levels of Estragole and methyl eugenol, displayed O-methyltransferase activities that accepted both chavicol and eugenol as substrates, generating Estragole and methyl eugenol, respectively. Chemotype SW that contains high levels of eugenol, but lacks both Estragole and methyl eugenol, had apparently no allylphenol dependent O-methyltransferase activities. These results indicate the presence of at least two types of allylphenol-specific O-methyltransferase activities in sweet basil chemotypes, one highly specific for chavicol; and a different one that can accept eugenol as a substrate. The relative availability and substrate specificities of these O-methyltransferase activities biochemically rationalizes the variation in the composition of the essential oils of these chemotypes. © 2000 Elsevier Science Ireland Ltd. All rights reserved.

  • Biosynthesis of Estragole and methyl-eugenol in sweet basil (Ocimum basilicum L). Developmental and chemotypic association of allylphenol O-methyltransferase activities
    Plant Science, 2000
    Co-Authors: Efraim Lewinsohn, Elena Lastochkin, David Chaimovitsh, Olga Larkov, Yaakov Tadmor, Uzi Ravid, Eli Putievsky, Nativ Dudai, Eran Pichersky
    Abstract:

    Sweet basil (Ocimum basilicum L., Lamiaceae) is a common herb, used for culinary and medicinal purposes. The essential oils of different sweet basil chemotypes contain various proportions of the allyl phenol derivatives Estragole (methyl chavicol), eugenol, and methyl eugenol, as well as the monoterpene alcohol linalool. To monitor the developmental regulation of Estragole biosynthesis in sweet basil, an enzymatic assay for S-adenosyl-L-methionine (SAM):chavicol O-methyltransferase activity was developed. Young leaves display high levels of chavicol O-methyltransferase activity, but the activity was negligible in older leaves, indicating that the O-methylation of chavicol primarily occurs early during leaf development. The O-methyltransferase activities detected in different sweet basil genotypes differed in their substrate specificities towards the methyl acceptor substrate. In the high-Estragole-containing chemotype R3, the O-methyltransferase activity was highly specific for chavicol, while eugenol was virtually not O-methylated. In contrast, chemotype 147:97, that contains equal levels of Estragole and methyl eugenol, displayed O-methyltransferase activities that accepted both chavicol and eugenol as substrates, generating Estragole and methyl eugenol, respectively. Chemotype SW that contains high levels of eugenol, but lacks both Estragole and methyl eugenol, had apparently no allylphenol dependent O-methyltransferase activities. These results indicate the presence of at least two types of allylphenol-specific O-methyltransferase activities in sweet basil chemotypes, one highly specific for chavicol; and a different one that can accept eugenol as a substrate. The relative availability and substrate specificities of these O-methyltransferase activities biochemically rationalizes the variation in the composition of the essential oils of these chemotypes. © 2000 Elsevier Science Ireland Ltd. All rights reserved.

  • Chemical variation among indigenous populations of Foeniculum vulgare var. vulgare in Israel.
    Planta Medica, 1999
    Co-Authors: O Barazani, Eli Putievsky, Efraim Lewinsohn, A Fait, Y Cohen, S Diminshtein, U Ravid, J Friedman
    Abstract:

    The composition of hexane extract constituents of ripe mericarps ("achenes") of eleven indigenous populations of Foeniculum vulgare var. vulgare (Apiaceae) was studied. Natural populations were selected along a gradient of annual rainfall from ca. 1000 mm in the northern region down to 125 mm in the Negev desert. Eighteen constituents, with Estragole, trans-anethole, fenchone, limonene and alpha-pinene as the major components were separated by GC-MS. Characterized by the level of Estragole and trans-anethole, four different groups were obtained: (1) highest Estragole (63%) and the lowest trans-ane-thole (3%) characterized the population of Mt. Meron; (2) estra-gole (39-47%) and trans-anethole (17-29%) in 3 mountainous populations; (3) Estragole (21-29%) and trans-anethole (38-49%) in the coastal and lowland populations; (4) two exceptional populations with the lowest content of Estragole (ca.8%) and high content of trans-anethole (55 and 74%). A reversed association between the content of Estragole and trans-anethole suggests a common precursor. In habitats with a high precipitation, the content of Estragole was high and that of trans-anethole was low, and vice versa under limited rainfall. It is proposed that the composition of oleoresins of F. vulgare var. vulgare could be governed by environmental conditions. Nevertheless, it is not ruled out that genetic variations account for the recorded differences.

Ivonne M.c.m. Rietjens - One of the best experts on this subject based on the ideXlab platform.

  • Estragole DNA adduct accumulation in human liver HepaRG cells upon repeated in vitro exposure.
    Toxicology letters, 2020
    Co-Authors: Shuo Yang, Sebastiaan Wesseling, Ivonne M.c.m. Rietjens
    Abstract:

    Accumulation of N2-(trans-isoestragol-3′-yl)-2′-deoxyguanosine (E-3′-N2-dG) DNA adducts derived from the alkenylbenzene Estragole upon repeated dose exposure was investigated since the repair of this adduct was previously shown to be inefficient. To this end human HepaRG cells were exposed to repeating cycles of 2 h exposure to 50 μM Estragole followed by 22 h repair to mimic daily exposure. The E-3′-N2-dG DNA adduct levels were quantified by LC–MS/MS after each cycle. The results show accumulation of E-3′-N2-dG DNA adducts at a rate of 17.53 adducts/108 nts/cycle. This rate at the dose level calculated by physiologically based kinetic (PBK) modeling to result in 50 μM was converted to a rate expected at average human daily intake of Estragole. The predicted time estimated to reach adduct levels reported at the BMD10 of the related alkenylbenzene methyleugenol of 10−100 adducts /108 nts upon average human daily intake of Estragole amounted to 8–80 (in rat) or 6–57 years (in human). It is concluded that the persistent nature of the E-3′-N2-dG DNA adducts may contribute to accumulation of substantial levels of DNA adducts upon prolonged dietary exposure.

  • Cellular levels and molecular dynamics simulations of Estragole DNA adducts point at inefficient repair resulting from limited distortion of the double-stranded DNA helix
    Archives of Toxicology, 2020
    Co-Authors: Shuo Yang, Matthias Diem, Sebastiaan Wesseling, Chris Oostenbrink, Jacques Vervoort, Ivonne M.c.m. Rietjens
    Abstract:

    Estragole, naturally occurring in a variety of herbs and spices, can form DNA adducts after bioactivation. Estragole DNA adduct formation and repair was studied in in vitro liver cell models, and a molecular dynamics simulation was used to investigate the conformation dependent (in)efficiency of N ^2-( trans -isoestragol-3′-yl)-2′-deoxyguanosine (E-3′- N ^2-dG) DNA adduct repair. HepG2, HepaRG cells, primary rat hepatocytes and CHO cells (including CHO wild-type and three NER-deficient mutants) were exposed to 50 μM Estragole or 1′-hydroxyEstragole and DNA adduct formation was quantified by LC–MS immediately following exposure and after a period of repair. Results obtained from CHO cell lines indicated that NER plays a role in repair of E-3′- N ^2-dG adducts, however, with limited efficiency since in the CHO wt cells 80% DNA adducts remained upon 24 h repair. Inefficiency of DNA repair was also found in HepaRG cells and primary rat hepatocytes. Changes in DNA structure resulting from E-3′- N ^2-dG adduct formation were investigated by molecular dynamics simulations. Results from molecular dynamics simulations revealed that conformational changes in double-stranded DNA by E-3′- N ^2-dG adduct formation are small, providing a possible explanation for the restrained repair, which may require larger distortions in the DNA structure. NER-mediated enzymatic repair of E-3′- N ^2-dG DNA adducts upon exposure to Estragole will be limited, providing opportunities for accumulation of damage upon repeated daily exposure. The inability of this enzymatic repair is likely due to a limited distortion of the DNA double-stranded helix resulting in inefficient activation of nucleotide excision repair.

  • Study on inter-ethnic human differences in bioactivation and detoxification of Estragole using physiologically based kinetic modeling
    Archives of Toxicology, 2017
    Co-Authors: Jia Ning, Sebastiaan Wesseling, Bert Spenkelink, Jochem Louisse, Ivonne M.c.m. Rietjens
    Abstract:

    Considering the rapid developments in food safety in the past decade in China, it is of importance to obtain insight into what extent safety and risk assessments of chemicals performed for the Caucasian population apply to the Chinese population. The aim of the present study was to determine physiologically based kinetic (PBK) modeling-based predictions for differences between Chinese and Caucasians in terms of metabolic bioactivation and detoxification of the food-borne genotoxic carcinogen Estragole. The PBK models were defined based on kinetic constants for hepatic metabolism derived from in vitro incubations using liver fractions of the two ethnic groups, and used to evaluate the inter-ethnic differences in metabolic activation and detoxification of Estragole. The models predicted that at realistic dietary intake levels, only 0.02% of the dose was converted to the ultimate carcinogenic metabolite 1′-sulfooxyEstragole in Chinese subjects, whereas this amounted to 0.09% of the dose in Caucasian subjects. Detoxification of 1′-hydroxyEstragole, mainly via conversion to 1′-oxoEstragole, was similar within the two ethnic groups. The 4.5-fold variation in formation of the ultimate carcinogenic metabolite of Estragole accompanied by similar rates of detoxification may indicate a lower risk of Estragole for the Chinese population at similar levels of exposure. The study provides a proof of principle for how PBK modeling can identify differences in ethnic sensitivity and provide a more refined risk assessment for a specific ethnic group for a compound of concern.

  • Evaluation of Interindividual Human Variation in Bioactivation and DNA Adduct Formation of Estragole in Liver Predicted by Physiologically Based Kinetic/Dynamic and Monte Carlo Modeling
    Chemical research in toxicology, 2016
    Co-Authors: Ans Punt, Benoît Schilter, Peter J. Van Bladeren, Alicia Paini, A. Spenkelink, Gabriele Scholz, Ivonne M.c.m. Rietjens
    Abstract:

    Estragole is a known hepatocarcinogen in rodents at high doses following metabolic conversion to the DNA-reactive metabolite 1'-sulfooxyEstragole. The aim of the present study was to model possible levels of DNA adduct formation in (individual) humans upon exposure to Estragole. This was done by extending a previously defined PBK model for Estragole in humans to include (i) new data on interindividual variation in the kinetics for the major PBK model parameters influencing the formation of 1'-sulfooxyEstragole, (ii) an equation describing the relationship between 1'-sulfooxyEstragole and DNA adduct formation, (iii) Monte Carlo modeling to simulate interindividual human variation in DNA adduct formation in the population, and (iv) a comparison of the predictions made to human data on DNA adduct formation for the related alkenylbenzene methyleugenol. Adequate model predictions could be made, with the predicted DNA adduct levels at the estimated daily intake of Estragole of 0.01 mg/kg bw ranging between 1.6 and 8.8 adducts in 10(8) nucleotides (nts) (50th and 99th percentiles, respectively). This is somewhat lower than values reported in the literature for the related alkenylbenzene methyleugenol in surgical human liver samples. The predicted levels seem to be below DNA adduct levels that are linked with tumor formation by alkenylbenzenes in rodents, which were estimated to amount to 188-500 adducts per 10(8) nts at the BMD10 values of Estragole and methyleugenol. Although this does not seem to point to a significant health concern for human dietary exposure, drawing firm conclusions may have to await further validation of the model's predictions.

  • Chemical analysis of Estragole in fennel based teas and associated safety assessment using the Margin of Exposure (MOE) approach.
    Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2013
    Co-Authors: Suzanne J. P. L. Van Den Berg, Wasma Alhusainy, Patrizia Restani, Ivonne M.c.m. Rietjens
    Abstract:

    Abstract This study describes the analysis of Estragole in dry fennel preparations and in infusions prepared from them and an associated safety assessment. A wide range of Estragole levels of 0.15–13.3 mg/g dry fennel preparation was found. The Estragole content in infusions was considerably lower ranging between 0.4 and 133.4 μg/25 mL infusion prepared from 1 g dry material. Infusions prepared from whole fennel fruits contained about 3-fold less Estragole compared to infusions prepared from fine cut fennel material. Safety assessment was performed using the Margin of Exposure (MOE) approach comparing available tumour data to the estimated daily Estragole intakes from the consumption of 1–3 cups fennel tea. MOEs obtained for adults generally point at a low priority for risk management, especially when one cup of fennel tea is used daily during lifetime. MOEs for use of fennel teas by children were generally

Belgin Coşge - One of the best experts on this subject based on the ideXlab platform.