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Pierre S. Haddad - One of the best experts on this subject based on the ideXlab platform.
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Labrador Tea (Rhododendron groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model
European Journal of Nutrition, 2016Co-Authors: Meriem Ouchfoun, John T. Arnason, Antoine Brault, Lina Musallam, Hoda M. Eid, Diane Vallerand, Pierre S. HaddadAbstract:Purpose Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador Tea [ Rhododendron groenlandicum (Oeder) Kron and Judd], a beverage and Medicinal Tea used by the Cree Nations of northern Quebec. Methods C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant’s molecular mechanisms. Results Labrador Tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic sTeatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador Tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic sTeatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). Conclusions Labrador Tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
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Labrador Tea (Rhododendron groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model.
European Journal of Nutrition, 2015Co-Authors: Meriem Ouchfoun, John T. Arnason, Antoine Brault, Lina Musallam, Hoda M. Eid, Diane Vallerand, Pierre S. HaddadAbstract:Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador Tea [Rhododendron groenlandicum (Oeder) Kron and Judd], a beverage and Medicinal Tea used by the Cree Nations of northern Quebec. C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant’s molecular mechanisms. Labrador Tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic sTeatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador Tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic sTeatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). Labrador Tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
William J. Foley - One of the best experts on this subject based on the ideXlab platform.
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Foliar Terpene Chemotypes and Herbivory Determine Variation in Plant Volatile Emissions
Journal of Chemical Ecology, 2018Co-Authors: Carlos Bustos-segura, William J. FoleyAbstract:Plants that synthesize and store terpenes in specialized cells accumulate large concentrations of these compounds while avoiding autotoxicity. Stored terpenes may influence the quantity and profile of volatile compounds that are emitted into the environment and the subsequent role of those volatiles in mediating the activity of herbivores. The Australian Medicinal Tea tree, Melaleuca alternifolia, occurs as several distinct terpene chemotypes. We studied the profile of its terpene emissions to understand how variations in stored foliar terpenes influenced emissions, both constitutive and when damaged either by herbivores or mechanically. We found that foliar chemistry influenced differences in the composition of terpene emissions, but those emissions were minimal in intact plants. When plants were damaged by herbivores or mechanically, the emissions were greatly increased and the composition corresponded to the constitutive terpenes and the volatility of each compound, suggesting the main origin of emissions is the stored terpenes and not de novo biosynthesized volatiles. However, herbivores modified the composition of the volatile emissions in only one chemotype, probably due to the oxidative metabolism of 1,8-cineole by the beetles. We also tested whether the foliar terpene blend acted as an attractant for the specialized leaf beetles Paropsisterna tigrina and Faex sp. and a parasitoid fly, Anagonia zentae . None of these species responded to extracts of young leaves in an olfactometer, so we found no evidence that these species use plant odor cues for host location in laboratory conditions.
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Four terpene synthases contribute to the generation of chemotypes in Tea tree (Melaleuca alternifolia)
BMC Plant Biology, 2017Co-Authors: Amanda Padovan, Carsten Külheim, Andras Keszei, Yasmin Hassan, Sandra T. Krause, Tobias G. Köllner, Jörg Degenhardt, Jonathan Gershenzon, William J. FoleyAbstract:Background Terpene rich leaves are a characteristic of Myrtaceae. There is significant qualitative variation in the terpene profile of plants within a single species, which is observable as “chemotypes”. Understanding the molecular basis of chemotypic variation will help explain how such variation is maintained in natural populations as well as allowing focussed breeding for those terpenes sought by industry. The leaves of the Medicinal Tea tree, Melaleuca alternifolia , are used to produce terpinen-4-ol rich Tea tree oil, but there are six naturally occurring chemotypes; three cardinal chemotypes (dominated by terpinen-4-ol, terpinolene and 1,8-cineole, respectively) and three intermediates. It has been predicted that three distinct terpene synthases could be responsible for the maintenance of chemotypic variation in this species. Results We isolated and characterised the most abundant terpene synthases (TPSs) from the three cardinal chemotypes of M. alternifolia . Functional characterisation of these enzymes shows that they produce the dominant compounds in the foliar terpene profile of all six chemotypes. Using RNA-Seq, we investigated the expression of these and 24 additional putative terpene synthases in young leaves of all six chemotypes of M. alternifolia . Conclusions Despite contributing to the variation patterns observed, variation in gene expression of the three TPS genes is not enough to explain all variation for the maintenance of chemotypes. Other candidate terpene synthases as well as other levels of regulation must also be involved. The results of this study provide novel insights into the complexity of terpene biosynthesis in natural populations of a non-model organism.
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Four terpene synthases contribute to the generation of chemotypes in Tea tree (Melaleuca alternifolia).
BMC plant biology, 2017Co-Authors: Amanda Padovan, Carsten Külheim, Andras Keszei, Yasmin Hassan, Sandra T. Krause, Tobias G. Köllner, Jörg Degenhardt, Jonathan Gershenzon, William J. FoleyAbstract:Terpene rich leaves are a characteristic of Myrtaceae. There is significant qualitative variation in the terpene profile of plants within a single species, which is observable as “chemotypes”. Understanding the molecular basis of chemotypic variation will help explain how such variation is maintained in natural populations as well as allowing focussed breeding for those terpenes sought by industry. The leaves of the Medicinal Tea tree, Melaleuca alternifolia, are used to produce terpinen-4-ol rich Tea tree oil, but there are six naturally occurring chemotypes; three cardinal chemotypes (dominated by terpinen-4-ol, terpinolene and 1,8-cineole, respectively) and three intermediates. It has been predicted that three distinct terpene synthases could be responsible for the maintenance of chemotypic variation in this species. We isolated and characterised the most abundant terpene synthases (TPSs) from the three cardinal chemotypes of M. alternifolia. Functional characterisation of these enzymes shows that they produce the dominant compounds in the foliar terpene profile of all six chemotypes. Using RNA-Seq, we investigated the expression of these and 24 additional putative terpene synthases in young leaves of all six chemotypes of M. alternifolia. Despite contributing to the variation patterns observed, variation in gene expression of the three TPS genes is not enough to explain all variation for the maintenance of chemotypes. Other candidate terpene synthases as well as other levels of regulation must also be involved. The results of this study provide novel insights into the complexity of terpene biosynthesis in natural populations of a non-model organism.
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The Yield of essential oils in Melaleuca alternifolia (Myrtaceae) is regulated through transcript abundance of genes in the MEP pathway
PloS one, 2013Co-Authors: Hamish Webb, Robert Lanfear, John D. Hamill, William J. Foley, Carsten KülheimAbstract:Medicinal Tea tree (Melaleuca alternifolia) leaves contain large amounts of an essential oil, dominated by monoterpenes. Several enzymes of the chloroplastic methylerythritol phosphate (MEP) pathway are hypothesised to act as bottlenecks to the production of monoterpenes. We investigated, whether transcript abundance of genes encoding for enzymes of the MEP pathway were correlated with foliar terpenes in M. alternifolia using a population of 48 individuals that ranged in their oil concentration from 39 -122 mg.g DM−1. Our study shows that most genes in the MEP pathway are co-regulated and that the expression of multiple genes within the MEP pathway is correlated with oil yield. Using multiple regression analysis, variation in expression of MEP pathway genes explained 87% of variation in foliar monoterpene concentrations. The data also suggest that sesquiterpenes in M. alternifolia are synthesised, at least in part, from isopentenyl pyrophosphate originating from the plastid via the MEP pathway.
Dirk W. Lachenmeier - One of the best experts on this subject based on the ideXlab platform.
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determination of the biologically active flavour substances thujone and camphor in foods and medicines containing sage salvia officinalis l
Chemistry Central Journal, 2011Co-Authors: Stephan G. Walch, Wolf Stuhlinger, Thomas Kuballa, Dirk W. LachenmeierAbstract:The sage plant Salvia officinalis L. is used as ingredient in foods and beverages as well as in herbal Medicinal products. A major use is in the form of aqueous infusions as sage Tea, which is legal to be sold as either food or medicine. Sage may contain two health relevant substances, thujone and camphor. The aim of this study was to develop and validate an analytical methodology to determine these active principles of sage and give a first overview of their concentrations in a wide variety of sage foods and medicines. A GC/MS procedure was applied for the analysis of α- and β-thujone and camphor with cyclodecanone as internal standard. The precision was between 0.8 and 12.6%, linearity was obtained from 0.1 - 80 mg/L. The recoveries of spiked samples were between 93.7 and 104.0% (average 99.1%). The time of infusion had a considerable influence on the content of analytes found in the Teas. During the brewing time, thujone and camphor show an increase up to about 5 min, after which saturation is reached. No effect was found for preparation with or without a lid on the pot used for brewing the infusion. Compared to extracts with ethanol (60% vol), which provide a maximum yield, an average of 30% thujone are recovered in the aqueous Tea preparations. The average thujone and camphor contents were 4.4 mg/L and 16.7 mg/L in food Tea infusions and 11.3 mg/L and 25.4 mg/L in Medicinal Tea infusions. The developed methodology allows the efficient determination of thujone and camphor in a wide variety of sage food and medicine matrices and can be applied to conduct surveys for exposure assessment. The current results suggest that on average between 3 and 6 cups of sage Tea could be daily consumed without reaching toxicological thresholds.
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Determination of the biologically active flavour substances thujone and camphor in foods and medicines containing sage (Salvia officinalisL.)
Chemistry Central Journal, 2011Co-Authors: Stephan G. Walch, Wolf Stuhlinger, Thomas Kuballa, Dirk W. LachenmeierAbstract:Background The sage plant Salvia officinalis L. is used as ingredient in foods and beverages as well as in herbal Medicinal products. A major use is in the form of aqueous infusions as sage Tea, which is legal to be sold as either food or medicine. Sage may contain two health relevant substances, thujone and camphor. The aim of this study was to develop and validate an analytical methodology to determine these active principles of sage and give a first overview of their concentrations in a wide variety of sage foods and medicines. Results A GC/MS procedure was applied for the analysis of α- and β-thujone and camphor with cyclodecanone as internal standard. The precision was between 0.8 and 12.6%, linearity was obtained from 0.1 - 80 mg/L. The recoveries of spiked samples were between 93.7 and 104.0% (average 99.1%). The time of infusion had a considerable influence on the content of analytes found in the Teas. During the brewing time, thujone and camphor show an increase up to about 5 min, after which saturation is reached. No effect was found for preparation with or without a lid on the pot used for brewing the infusion. Compared to extracts with ethanol (60% vol), which provide a maximum yield, an average of 30% thujone are recovered in the aqueous Tea preparations. The average thujone and camphor contents were 4.4 mg/L and 16.7 mg/L in food Tea infusions and 11.3 mg/L and 25.4 mg/L in Medicinal Tea infusions. Conclusions The developed methodology allows the efficient determination of thujone and camphor in a wide variety of sage food and medicine matrices and can be applied to conduct surveys for exposure assessment. The current results suggest that on average between 3 and 6 cups of sage Tea could be daily consumed without reaching toxicological thresholds.
Meriem Ouchfoun - One of the best experts on this subject based on the ideXlab platform.
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Labrador Tea (Rhododendron groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model
European Journal of Nutrition, 2016Co-Authors: Meriem Ouchfoun, John T. Arnason, Antoine Brault, Lina Musallam, Hoda M. Eid, Diane Vallerand, Pierre S. HaddadAbstract:Purpose Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador Tea [ Rhododendron groenlandicum (Oeder) Kron and Judd], a beverage and Medicinal Tea used by the Cree Nations of northern Quebec. Methods C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant’s molecular mechanisms. Results Labrador Tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic sTeatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador Tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic sTeatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). Conclusions Labrador Tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
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Labrador Tea (Rhododendron groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model.
European Journal of Nutrition, 2015Co-Authors: Meriem Ouchfoun, John T. Arnason, Antoine Brault, Lina Musallam, Hoda M. Eid, Diane Vallerand, Pierre S. HaddadAbstract:Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador Tea [Rhododendron groenlandicum (Oeder) Kron and Judd], a beverage and Medicinal Tea used by the Cree Nations of northern Quebec. C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant’s molecular mechanisms. Labrador Tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic sTeatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador Tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic sTeatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). Labrador Tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
Carsten Külheim - One of the best experts on this subject based on the ideXlab platform.
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Four terpene synthases contribute to the generation of chemotypes in Tea tree (Melaleuca alternifolia)
BMC Plant Biology, 2017Co-Authors: Amanda Padovan, Carsten Külheim, Andras Keszei, Yasmin Hassan, Sandra T. Krause, Tobias G. Köllner, Jörg Degenhardt, Jonathan Gershenzon, William J. FoleyAbstract:Background Terpene rich leaves are a characteristic of Myrtaceae. There is significant qualitative variation in the terpene profile of plants within a single species, which is observable as “chemotypes”. Understanding the molecular basis of chemotypic variation will help explain how such variation is maintained in natural populations as well as allowing focussed breeding for those terpenes sought by industry. The leaves of the Medicinal Tea tree, Melaleuca alternifolia , are used to produce terpinen-4-ol rich Tea tree oil, but there are six naturally occurring chemotypes; three cardinal chemotypes (dominated by terpinen-4-ol, terpinolene and 1,8-cineole, respectively) and three intermediates. It has been predicted that three distinct terpene synthases could be responsible for the maintenance of chemotypic variation in this species. Results We isolated and characterised the most abundant terpene synthases (TPSs) from the three cardinal chemotypes of M. alternifolia . Functional characterisation of these enzymes shows that they produce the dominant compounds in the foliar terpene profile of all six chemotypes. Using RNA-Seq, we investigated the expression of these and 24 additional putative terpene synthases in young leaves of all six chemotypes of M. alternifolia . Conclusions Despite contributing to the variation patterns observed, variation in gene expression of the three TPS genes is not enough to explain all variation for the maintenance of chemotypes. Other candidate terpene synthases as well as other levels of regulation must also be involved. The results of this study provide novel insights into the complexity of terpene biosynthesis in natural populations of a non-model organism.
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Four terpene synthases contribute to the generation of chemotypes in Tea tree (Melaleuca alternifolia).
BMC plant biology, 2017Co-Authors: Amanda Padovan, Carsten Külheim, Andras Keszei, Yasmin Hassan, Sandra T. Krause, Tobias G. Köllner, Jörg Degenhardt, Jonathan Gershenzon, William J. FoleyAbstract:Terpene rich leaves are a characteristic of Myrtaceae. There is significant qualitative variation in the terpene profile of plants within a single species, which is observable as “chemotypes”. Understanding the molecular basis of chemotypic variation will help explain how such variation is maintained in natural populations as well as allowing focussed breeding for those terpenes sought by industry. The leaves of the Medicinal Tea tree, Melaleuca alternifolia, are used to produce terpinen-4-ol rich Tea tree oil, but there are six naturally occurring chemotypes; three cardinal chemotypes (dominated by terpinen-4-ol, terpinolene and 1,8-cineole, respectively) and three intermediates. It has been predicted that three distinct terpene synthases could be responsible for the maintenance of chemotypic variation in this species. We isolated and characterised the most abundant terpene synthases (TPSs) from the three cardinal chemotypes of M. alternifolia. Functional characterisation of these enzymes shows that they produce the dominant compounds in the foliar terpene profile of all six chemotypes. Using RNA-Seq, we investigated the expression of these and 24 additional putative terpene synthases in young leaves of all six chemotypes of M. alternifolia. Despite contributing to the variation patterns observed, variation in gene expression of the three TPS genes is not enough to explain all variation for the maintenance of chemotypes. Other candidate terpene synthases as well as other levels of regulation must also be involved. The results of this study provide novel insights into the complexity of terpene biosynthesis in natural populations of a non-model organism.
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Effects of Terpene Chemotypes of Melaleuca alternifolia on Two Specialist Leaf Beetles and Susceptibility to Myrtle Rust
Journal of Chemical Ecology, 2015Co-Authors: Carlos Bustos-segura, Carsten Külheim, William FoleyAbstract:Plant chemical polymorphisms, or plant chemotypes, are characterized by intraspecific discrete differences of plant secondary metabolites in the same plant tissue. Chemotypes that differ in foliar terpene composition are found commonly in Myrtaceae. In this study, we focused on terpene chemotypes of Medicinal Tea tree, Melalecua alternifolia, to explore whether this variation affects two specialist herbivores Paropsisterna tigrina and Faex sp. (Coleoptera: Chrysomelidae), and if this could explain the maintenance of this variation. We tested whether insect performance, oviposition preference, and plant damage were associated with different chemotypes. We found that larval growth rate of Faex sp. was higher in chemotypes with high concentrations of 1,8-cineole, and that oviposition preference depended on the chemotype of the larval diet. Although performance traits and preference for oviposition of P. tigrina did not vary among chemotypes, adults inflicted less damage on plants with a high concentration of terpinolene. Additionally, we tested whether different chemotypes showed different levels of susceptibility by myrtle rust ( Puccinia psidii) . We found that plants with a high concentration of 1,8-cineole were more likely to be infected under controlled conditions. Although there is evidence that terpene chemotypes are a mediator of the interaction with natural enemies, the most detrimental pest of this plant, P. tigrina , does not seem to be affected by variation in plant terpenes.
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The Yield of essential oils in Melaleuca alternifolia (Myrtaceae) is regulated through transcript abundance of genes in the MEP pathway
PloS one, 2013Co-Authors: Hamish Webb, Robert Lanfear, John D. Hamill, William J. Foley, Carsten KülheimAbstract:Medicinal Tea tree (Melaleuca alternifolia) leaves contain large amounts of an essential oil, dominated by monoterpenes. Several enzymes of the chloroplastic methylerythritol phosphate (MEP) pathway are hypothesised to act as bottlenecks to the production of monoterpenes. We investigated, whether transcript abundance of genes encoding for enzymes of the MEP pathway were correlated with foliar terpenes in M. alternifolia using a population of 48 individuals that ranged in their oil concentration from 39 -122 mg.g DM−1. Our study shows that most genes in the MEP pathway are co-regulated and that the expression of multiple genes within the MEP pathway is correlated with oil yield. Using multiple regression analysis, variation in expression of MEP pathway genes explained 87% of variation in foliar monoterpene concentrations. The data also suggest that sesquiterpenes in M. alternifolia are synthesised, at least in part, from isopentenyl pyrophosphate originating from the plastid via the MEP pathway.