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Indra Prakash - One of the best experts on this subject based on the ideXlab platform.

  • Five New Ent-Atisene Glycosides From Stevia rebaudiana:
    Natural Product Communications, 2019
    Co-Authors: Krishna Prasad Devkota, Romila D Charan, Catherine Ramirez, Tara M Snyder, Christopher Priedemann, Ryan Donovan, George Harrigan, Gil Ma, Indra Prakash
    Abstract:

    Five new ent-atisene Diterpene Glycosides (1-5) have been isolated from Stevia rebaudiana Bertoni. This adds to a list of only 2 new ent-atisene Diterpene Glycosides isolated previously from S. reb...

  • new Diterpene Glycosides from stevia rebaudiana bertoni rebaudioside viii and rebaudioside ixd
    Natural Product Communications, 2018
    Co-Authors: Allison Bechman, Cynthia Bunders, Krishna Prasad Devkota, Romila D Charan, Catherine Ramirez, Tara M Snyder, Christopher Priedemann, Indra Prakash
    Abstract:

    With our interest of new Diterpene Glycosides with better taste profile than Rebaudioside M, we isolated and characterized two steviol Glycosides with three additional glucose attached at the C-13 ...

  • Structures of Some Novel α-Glucosyl Diterpene Glycosides from the Glycosylation of Steviol Glycosides
    Molecules, 2014
    Co-Authors: Indra Prakash, Venkata Sai Prakash Chaturvedula
    Abstract:

    Four new minor Diterpene Glycosides with a rare α-glucosyl linkage were isolated from a cyclodextrin glycosyltransferase glucosylated stevia extract containing more than 98% steviol Glycosides. The new compounds were identified as 13-[(2-O-β-D-glucopyranosyl-3-O-(4-O-α-D-glucopyranosyl)-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-[(4-O-α-D-glucopyranosyl-β-D-glucopyranosyl) ester] (1), 13-[(2-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-[(4-O-(4-O-(4-O-α-D-glucopyranosyl)-α-D-glucopyranosyl)-α-D-glucopyranosyl)-β-D-glucopyranosyl ester] (2), 13-[(2-O-β-D-glucopyranosyl-3-O-(4-O-(4-O-(4-O-α-D-glucopyranosyl)-α-D-glucopyranosyl)-α-D-glucopyranosyl)-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid β-D-glucopyranosyl ester (3), and 13-[(2-O-β-D-glucopyranosyl-3-O-(4-O-(4-O-(4-O-α-D-glucopyranosyl)-α-D-glucopyranosyl)-α-D-glucopyranosyl)-β-D-glucopyranosyl- β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-[(4-O-α-D-glucopyranosyl-β-D-glucopyranosyl) ester] (4) on the basis of extensive NMR and mass spectral (MS) data as well as hydrolysis studies.

  • Additional Minor Diterpene Glycosides from Stevia rebaudiana Bertoni
    Molecules, 2013
    Co-Authors: Indra Prakash, Venkata Sai Prakash Chaturvedula
    Abstract:

    Two additional novel minor Diterpene Glycosides were isolated from the commercial extract of the leaves of Stevia rebaudiana Bertoni. The structures of the new compounds were identified as 13-{β-D-glucopyranosyl-(1→2)-O-[β-D-glucopyranosyl-(1→3)-β-D-glucopyranosyl-oxy} ent-kaur-16-en-19-oic acid {β-D-xylopyranosyl-(1→2)-O-[β-D-glucopyranosyl-(1→3)]-O-β-D-glucupyranosyl-ester} (1), and 13-{β-D-6-deoxy-glucopyranosyl-(1→2)-O-[β-D-glucopyranosyl-(1→3)-β-D-glucopyranosyl-oxy} ent-kaur-16-en-19-oic acid {β-D-glucopyranosyl-(1→2)-O-[β-D-glucopyranosyl-(1→3)-β-D-gluco-pyranosyl-ester} (2), on the basis of extensive 1D (1H- and 13C-) 2D NMR (COSY, HSQC and HMBC) and MS spectroscopic data as well as chemical studies.

  • hydrogenation of the exocyclic olefinic bond at c 16 c 17 position of ent kaurane Diterpene Glycosides of stevia rebaudiana using various catalysts
    International Journal of Molecular Sciences, 2013
    Co-Authors: Venkata Sai Prakash Chaturvedula, Indra Prakash
    Abstract:

    Catalytic hydrogenation of the exocyclic double bond present between C16 and C17 carbons of the four ent-kaurane Diterpene Glycosides namely rebaudioside A, rebaudioside B, rebaudioside C, and rebaudioside D isolated from Stevia rebaudiana has been carried out using Pt/C, Pd(OH)2, Rh/C, Raney Ni, PtO2, and 5% Pd/BaCO3 to their corresponding dihydro derivatives with 17α and 17β methyl group isomers. Reactions were performed using the above-mentioned catalysts with the solvents methanol, water, and ethanol/water (8:2) under various conditions. Synthesis of reduced steviol Glycosides was performed using straightforward chemistry and their structures were characterized on the basis of 1D and 2D NMR spectral data, including a comparison with reported spectral data.

Ian T Baldwin - One of the best experts on this subject based on the ideXlab platform.

  • specific decorations of 17 hydroxygeranyllinalool Diterpene Glycosides solve the autotoxicity problem of chemical defense in nicotiana attenuata
    The Plant Cell, 2021
    Co-Authors: Sven Heiling, Lucas Cortes Llorca, Klaus Gase, Axel Schmidt, Martin Schafer, Bernd Schneider, Rayko Halitschke, Emmanuel Gaquerel, Ian T Baldwin
    Abstract:

    The native diploid tobacco Nicotiana attenuata produces abundant, potent anti-herbivore defense metabolites known as 17-hydroxygeranyllinalool Diterpene Glycosides (HGL-DTGs) whose glycosylation and malonylation biosynthetic steps are regulated by jasmonate signaling. To characterize the biosynthetic pathway of HGL-DTGs, we conducted a genome-wide analysis of uridine diphosphate glycosyltransferases (UGTs) and identified 107 family-1 UGT members. The transcript levels of three UGTs were highly correlated with the transcript levels two key HGL-DTG biosynthetic genes: geranylgeranyl diphosphate synthase (NaGGPPS) and geranyllinalool synthase (NaGLS). NaGLS's role in HGL-DTG biosynthesis was confirmed by virus-induced gene silencing. Silencing the UDP-rhamnosyltransferase gene UGT91T1 demonstrated its role in the rhamnosylation of HGL-DTGs. In vitro enzyme assays revealed that UGT74P3 and UGT74P4 use UDP-glucose for the glucosylation of 17-hydroxygeranyllinalool (17-HGL) to lyciumoside I. Plants with stable silencing of UGT74P3 and UGT74P5 were severely developmentally deformed, pointing to a phytotoxic effect of the aglycone. The application of synthetic 17-HGL and silencing of the UGTs in HGL-DTG-free plants confirmed this phytotoxic effect. Feeding assays with tobacco hornworm (Manduca sexta) larvae revealed the defensive functions of the glucosylation and rhamnosylation steps in HGL-DTG biosynthesis. Glucosylation of 17-HGL is therefore a critical step that contributes to the resulting metabolites' defensive function and solves the autotoxicity problem of this potent chemical defense.

  • specific decorations of 17 hydroxygeranyllinalool Diterpene Glycosides solve the autotoxicity problem of chemical defense in nicotiana attenuata
    bioRxiv, 2020
    Co-Authors: Sven Heiling, Lucas Cortes Llorca, Klaus Gase, Axel Schmidt, Bernd Schneider, Rayko Halitschke, Emmanuel Gaquerel, Martin Schaefer, Ian T Baldwin
    Abstract:

    17-hydroxygeranyllinalool Diterpene Glycosides (HGL-DTGs) are abundant and potent anti-herbivore defense metabolites in Nicotiana attenuata whose glycosylation and malonylation biosynthetic steps are regulated by jasmonate signaling. To characterize the biosynthetic pathway of HGL-DTGs, we conducted a genome-wide analysis of uridine diphosphate glycosyltransferases (UGTs) and identified 107 members of family-1 UGTs. Tissue-specific time-course transcriptional profiling revealed that the transcripts of three UGTs were highly correlated with two HGL-DTG key biosynthetic genes: geranylgeranyl diphosphate synthase (NaGGPPS) and geranyllinalool synthase (NaGLS). NaGLS9s role in HGL-DTG biosynthesis was confirmed by virus-induced gene-silencing. Silencing the UDP-rhamnosyltransferase, UGT91T1, indicated its role in the rhamnosylation of HGL-DTGs. In vitro enzyme assays revealed that UGT74P3 and UGT74P4 use UDP-glucose for the glucosylation of 17-hydroxygeranyllinalool (17-HGL) to lyciumoside I. UGT74P3 and UGT74P5 stably silenced plants were severely developmentally deformed, suggesting a phytotoxic effect of 17-HGL. Applications of synthetic 17-HGL and silencing of these UGTs in HGL-DTG-free plants confirmed the phytotoxic effect of 17-HGL. Feeding assays with Manduca sexta larvae revealed the defensive functions of the glucosylation and rhamnosylation steps in HGL-DTG biosynthesis. Glucosylation is a critical step that contributes to the metabolites9 defensive function and solves the autotoxicity problem of this potent chemical defense.

  • Silencing Brassinosteroid Receptor BRI1 Impairs Herbivory‐elicited Accumulation of Jasmonic Acid‐isoleucine and Diterpene Glycosides, but not Jasmonic Acid and Trypsin Proteinase Inhibitors in Nicotiana attenuata
    Journal of Integrative Plant Biology, 2013
    Co-Authors: Da-hai Yang, Ian T Baldwin, Jianqiang Wu
    Abstract:

    The brassinosteroid (BR) receptor, BR insensitive 1 (BRI1), plays a critical role in plant development, but whether BRI1-mediated BR signaling is involved in plant defense responses to herbivores was largely unknown. Here, we examined the function of BRI1 in the resistance of Nicotiana attenuata (Solanaceae) to its specialist insect herbivore Manduca sexta. Jasmonic acid (JA) and JA-isoleucine conjugate (JA-Ile) are important hormones that mediate resistance to herbivores and we found that after wounding or simulated herbivory NaBRI1 had little effect on JA levels, but was important for the induction of JA-Ile. Further experiments revealed that decreased JAR (the enzyme for JA-Ile production) activity and availability of Ile in NaBRI1-silenced plants were likely responsible for the low JA-Ile levels. Consistently, M. sexta larvae gained more weight on NaBRI1-silenced plants than on the control plants. Quantification of insect feeding-induced secondary metabolites revealed that silencing NaBRI1 resulted in decreased levels of carbon-rich defensive secondary metabolites (hydroxygeranyllinalool Diterpene Glycosides, chlorogenic acid, and rutin), but had little effect on the nitrogen-rich ones (nicotine and trypsin proteinase inhibitors). Thus, NaBRI1-mediated BR signaling is likely involved in plant defense responses to M. sexta, including maintaining JA-Ile levels and the accumulation of several carbon-rich defensive secondary metabolites.

  • uvb radiation and 17 hydroxygeranyllinalool Diterpene Glycosides provide durable resistance against mirid tupiocoris notatus attack in field grown nicotiana attenuata plants
    Plant Cell and Environment, 2013
    Co-Authors: Truong Son Dinh, Ivan Galis, Ian T Baldwin
    Abstract:

    Depending on geographical location, plants are exposed to variable amounts of UVB radiation and herbivore attack. Because the role(s) of UVB in the priming and/or accumulation of plant defence metabolites against herbivores are not well understood, we used field-grown Nicotiana attenuata plants to explore the effects of UVB on herbivore performance. Consistent with previous reports, UVB-exposed plants accumulated higher levels of ultraviolet (UV)-absorbing compounds (rutin, chlorogenic acid, crypto-chlorogenic acid and dicaffeoylspermidine). Furthermore, UVB increased the accumulation of jasmonic acid, jasmonoyl-L-isoleucine and abscisic acid, all phytohormones which regulate plant defence against biotic and abiotic stress. In herbivore bioassays, N. attenuata plants experimentally protected from UVB were more infested by mirids in three consecutive field seasons. Among defence metabolites measured, 17-hydroxygeranyllinalool Diterpene Glycosides (HGL-DTGs) showed strongly altered accumulation patterns. While constitutive HGL-DTGs levels were higher under UVB, N. attenuata plants exposed to mirid bugs (Tupiocoris notatus) had still more HGL-DTGs under UVB, and mirids preferred to feed on HGL-DTGs-silenced plants when other UVB protecting factors were eliminated by UVB filters. We conclude that UVB exposure not only stimulates UV protective screens but also affects plant defence mechanisms, such as HGL-DTGs accumulation, and modulates ecological interactions of N. attenuata with its herbivores in nature.

  • silencing brassinosteroid receptor bri1 impairs herbivory elicited accumulation of jasmonic acid isoleucine and Diterpene Glycosides but not jasmonic acid and trypsin proteinase inhibitors in nicotiana attenuata
    Journal of Integrative Plant Biology, 2013
    Co-Authors: Da-hai Yang, Ian T Baldwin
    Abstract:

    The brassinosteroid (BR) receptor, BR insensitive 1 (BRI1), plays a critical role in plant development, but whether BRI1-mediated BR signaling is involved in plant defense responses to herbivores was largely unknown. Here, we examined the function of BRI1 in the resistance of Nicotiana attenuata (Solanaceae) to its specialist insect herbivore Manduca sexta. Jasmonic acid (JA) and JA-isoleucine conjugate (JA-Ile) are important hormones that mediate resistance to herbivores and we found that after wounding or simulated herbivory NaBRI1 had little effect on JA levels, but was important for the induction of JA-Ile. Further experiments revealed that decreased JAR (the enzyme for JA-Ile production) activity and availability of Ile in NaBRI1-silenced plants were likely responsible for the low JA-Ile levels. Consistently, M. sexta larvae gained more weight on NaBRI1-silenced plants than on the control plants. Quantification of insect feeding-induced secondary metabolites revealed that silencing NaBRI1 resulted in decreased levels of carbon-rich defensive secondary metabolites (hydroxygeranyllinalool Diterpene Glycosides, chlorogenic acid, and rutin), but had little effect on the nitrogen-rich ones (nicotine and trypsin proteinase inhibitors). Thus, NaBRI1-mediated BR signaling is likely involved in plant defense responses to M. sexta, including maintaining JA-Ile levels and the accumulation of several carbon-rich defensive secondary metabolites.

Venkata Sai Prakash Chaturvedula - One of the best experts on this subject based on the ideXlab platform.

  • Structures of Some Novel α-Glucosyl Diterpene Glycosides from the Glycosylation of Steviol Glycosides
    Molecules, 2014
    Co-Authors: Indra Prakash, Venkata Sai Prakash Chaturvedula
    Abstract:

    Four new minor Diterpene Glycosides with a rare α-glucosyl linkage were isolated from a cyclodextrin glycosyltransferase glucosylated stevia extract containing more than 98% steviol Glycosides. The new compounds were identified as 13-[(2-O-β-D-glucopyranosyl-3-O-(4-O-α-D-glucopyranosyl)-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-[(4-O-α-D-glucopyranosyl-β-D-glucopyranosyl) ester] (1), 13-[(2-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-[(4-O-(4-O-(4-O-α-D-glucopyranosyl)-α-D-glucopyranosyl)-α-D-glucopyranosyl)-β-D-glucopyranosyl ester] (2), 13-[(2-O-β-D-glucopyranosyl-3-O-(4-O-(4-O-(4-O-α-D-glucopyranosyl)-α-D-glucopyranosyl)-α-D-glucopyranosyl)-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid β-D-glucopyranosyl ester (3), and 13-[(2-O-β-D-glucopyranosyl-3-O-(4-O-(4-O-(4-O-α-D-glucopyranosyl)-α-D-glucopyranosyl)-α-D-glucopyranosyl)-β-D-glucopyranosyl- β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-[(4-O-α-D-glucopyranosyl-β-D-glucopyranosyl) ester] (4) on the basis of extensive NMR and mass spectral (MS) data as well as hydrolysis studies.

  • Additional Minor Diterpene Glycosides from Stevia rebaudiana Bertoni
    Molecules, 2013
    Co-Authors: Indra Prakash, Venkata Sai Prakash Chaturvedula
    Abstract:

    Two additional novel minor Diterpene Glycosides were isolated from the commercial extract of the leaves of Stevia rebaudiana Bertoni. The structures of the new compounds were identified as 13-{β-D-glucopyranosyl-(1→2)-O-[β-D-glucopyranosyl-(1→3)-β-D-glucopyranosyl-oxy} ent-kaur-16-en-19-oic acid {β-D-xylopyranosyl-(1→2)-O-[β-D-glucopyranosyl-(1→3)]-O-β-D-glucupyranosyl-ester} (1), and 13-{β-D-6-deoxy-glucopyranosyl-(1→2)-O-[β-D-glucopyranosyl-(1→3)-β-D-glucopyranosyl-oxy} ent-kaur-16-en-19-oic acid {β-D-glucopyranosyl-(1→2)-O-[β-D-glucopyranosyl-(1→3)-β-D-gluco-pyranosyl-ester} (2), on the basis of extensive 1D (1H- and 13C-) 2D NMR (COSY, HSQC and HMBC) and MS spectroscopic data as well as chemical studies.

  • Hydrogenation of the exocyclic olefinic bond at C-16/C-17 position of ent-kaurane Diterpene Glycosides of Stevia rebaudiana using various catalysts.
    International Journal of Molecular Sciences, 2013
    Co-Authors: Venkata Sai Prakash Chaturvedula, Indra Prakash
    Abstract:

    Catalytic hydrogenation of the exocyclic double bond present between C16 and C17 carbons of the four ent-kaurane Diterpene Glycosides namely rebaudioside A, rebaudioside B, rebaudioside C, and rebaudioside D isolated from Stevia rebaudiana has been carried out using Pt/C, Pd(OH)2, Rh/C, Raney Ni, PtO2, and 5% Pd/BaCO3 to their corresponding dihydro derivatives with 17α and 17β methyl group isomers. Reactions were performed using the above-mentioned catalysts with the solvents methanol, water, and ethanol/water (8:2) under various conditions. Synthesis of reduced steviol Glycosides was performed using straightforward chemistry and their structures were characterized on the basis of 1D and 2D NMR spectral data, including a comparison with reported spectral data.

  • hydrogenation of the exocyclic olefinic bond at c 16 c 17 position of ent kaurane Diterpene Glycosides of stevia rebaudiana using various catalysts
    International Journal of Molecular Sciences, 2013
    Co-Authors: Venkata Sai Prakash Chaturvedula, Indra Prakash
    Abstract:

    Catalytic hydrogenation of the exocyclic double bond present between C16 and C17 carbons of the four ent-kaurane Diterpene Glycosides namely rebaudioside A, rebaudioside B, rebaudioside C, and rebaudioside D isolated from Stevia rebaudiana has been carried out using Pt/C, Pd(OH)2, Rh/C, Raney Ni, PtO2, and 5% Pd/BaCO3 to their corresponding dihydro derivatives with 17α and 17β methyl group isomers. Reactions were performed using the above-mentioned catalysts with the solvents methanol, water, and ethanol/water (8:2) under various conditions. Synthesis of reduced steviol Glycosides was performed using straightforward chemistry and their structures were characterized on the basis of 1D and 2D NMR spectral data, including a comparison with reported spectral data.

  • IR Spectral Analysis of Diterpene Glycosides Isolated from Stevia rebaudiana
    Food and Nutrition Sciences, 2012
    Co-Authors: Venkata Sai Prakash Chaturvedula, Christopher Mubarak, Indra Prakash
    Abstract:

    The objective is to identify the Infra-Red (IR) spectral analysis of the Diterpene Glycosides present in the commercial extracts of Stevia rebaudiana was achieved by PerkinElmer Spectrum 400 Fourier Transform (FT) spectrometer employing a PerkinElmer Universal Attenuated Total Reflection (ATR) accessory. Using this technique the IR spectral pattern of 15 steviol Glycosides which belongs to three different classes of ent-kaurane Diterpene Glycosides namely ent-13-hydroxykaur-16-en-19-oic acid, ent-13-hydroxykaur-15-en-19-oic acid, and 13-methyl-16-oxo-17-norent- kauran-19-oic acid were identified. From the wave numbers found for all 15 steviol Glycosides, it was observed that that though there are differences in the number of sugar units, nature of sugar units, and their attachments; there are not any notable differences in the IR values.

James D. Mcchesney - One of the best experts on this subject based on the ideXlab platform.

  • development of a high performance liquid chromatography procedure to identify known and detect novel c 13 oligosaccharide moieties in Diterpene Glycosides from stevia rebaudiana bertoni bertoni asteraceae structure elucidation of rebaudiosides v and
    IEEE Journal of Solid-state Circuits, 2017
    Co-Authors: Wilmer H. Perera, Douglas L. Rodenburg, Kamilla Alves, Ion Ghiviriga, Raquel Carvalho, James D. Mcchesney
    Abstract:

    As an aid for structure elucidation of new steviol Glycosides, reversed-phase C18 high-performance liquid chromatography method was developed with several previously characterized Diterpene Glycosides, to identify known and detect novel aglycone-C13 oligosaccharide moieties and indirectly identify C-19 interlinkages. Elution order of several Diterpene Glycosides and their aglycone-C13 oligosaccharide substituted with different sugar arrangements were also summarized. Comparison of the retention time of a product obtained after alkaline hydrolysis with the aglycone-C-13 portions of known compounds reported herein allowed us to deduce the exact positions of the sugars in the C-13 oligosaccharide portion. The elution position of several steviol Glycosides with an ent-kaurene skeleton was helpful to describe an identification key. Two previously uncharacterized Diterpene Glycosides together with two known compounds were isolated from a commercial Stevia rebaudiana leaf extract. One was found to be 13-[(2-O-β-d-xylopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid-(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl) ester (rebaudioside V), whereas the other was determined to be 13-[(2-O-β-d-xylopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid-(2-O-α-l-rhamnopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl) ester (rebaudioside W). Previously reported compounds were isolated in gram quantities and identified as rebaudioside J and rebaudioside H. In addition, a C-19 sugar-free derivative was also prepared from rebaudioside H to afford rebaudioside H1 . Chemical structures were partially determined by the high-performance liquid chromatography method and unambiguously characterized by using one-dimensional and two-dimensional nuclear magnetic resonance experiments.

  • Development of a high‐performance liquid chromatography procedure to identify known and detect novel C‐13 oligosaccharide moieties in Diterpene Glycosides from Stevia rebaudiana (Bertoni) Bertoni (Asteraceae): Structure elucidation of rebaudiosides V
    IEEE Journal of Solid-state Circuits, 2017
    Co-Authors: Wilmer H. Perera, Douglas L. Rodenburg, Kamilla Alves, Ion Ghiviriga, Raquel Carvalho, James D. Mcchesney
    Abstract:

    As an aid for structure elucidation of new steviol Glycosides, reversed-phase C18 high-performance liquid chromatography method was developed with several previously characterized Diterpene Glycosides, to identify known and detect novel aglycone-C13 oligosaccharide moieties and indirectly identify C-19 interlinkages. Elution order of several Diterpene Glycosides and their aglycone-C13 oligosaccharide substituted with different sugar arrangements were also summarized. Comparison of the retention time of a product obtained after alkaline hydrolysis with the alycone-C-13 portions of known compounds reported herein allowed us to deduce the exact positions of the sugars in the C-13 oligosaccharide portion. The elution position of several steviol Glycosides with an ent-kaurene skeleton was helpful to describe an identification key. Two previously uncharacterized Diterpene Glycosides together with two known compounds were isolated from a commercial Stevia rebaudiana leaf extract. One was found to be 13-[(2-O-β-D-xylopyranosyl-3-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid-(2-O-β-D-glucopyranosyl-β-D-glucopyranosyl) ester (rebaudioside V), whereas the other was determined to be 13-[(2-O-β-D-xylopyranosyl-3-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid-(2-O-α-L-rhamnopyranosyl-3-O-β-D-glucopyranosyl-β-D-glucopyranosyl) ester (rebaudioside W). Previously reported compounds were isolated in gram quantities and identified as rebaudioside J and rebaudioside H. In addition, a C-19 sugar-free derivative was also prepared from rebaudioside H to afford rebaudioside H1. Chemical structures were partially determined by the high-performance liquid chromatography method and unambiguously characterized by using 1D and 2D NMR experiments. This article is protected by copyright. All rights reserved

  • Rebaudiosides R and S, Minor Diterpene Glycosides from the Leaves of Stevia rebaudiana
    Journal of Natural Products, 2016
    Co-Authors: Mohamed A. Ibrahim, Douglas L. Rodenburg, Kamilla Alves, Frank R. Fronczek, Wilmer H. Perera, John J. Bowling, James D. Mcchesney
    Abstract:

    Two new Diterpene Glycosides have been isolated from a commercial extract of the leaves of Stevia rebaudiana. Compound 1 was shown to be 13-[(2-O-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-xylopyranosyl)oxy]ent-kaur-16-en-19-oic acid β-d-glucopyranosyl ester (rebaudioside R), while compound 2 was determined to be 13-[(2-O-α-d-glucopyranosyl-β-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid 2-O-α-l-rhamnopyranosyl-β-d-glucopyranosyl ester (rebaudioside S). Six additional known compounds were identified, dulcoside B, 13-[(2-O-β-d-xylopyranosyl-β-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid β-d-glucopyranosyl ester, eugenol diglucoside, rebaudioside G, 13-[(2-O-6-deoxy-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid β-d-glucopyranosyl ester, and rebaudioside D (3), respectively. The structures of 1 and 2 were determined based on comprehensive 1D and 2D NMR (COSY, HSQC, and HMBC) studies. A high-quality crystal of compound 3 allowed confirmation of its structu...

  • rebaudiosides r and s minor Diterpene Glycosides from the leaves of stevia rebaudiana
    Journal of Natural Products, 2016
    Co-Authors: Mohamed A. Ibrahim, Douglas L. Rodenburg, Kamilla Alves, Frank R. Fronczek, Wilmer H. Perera, John Bowling, James D. Mcchesney
    Abstract:

    Two new Diterpene Glycosides have been isolated from a commercial extract of the leaves of Stevia rebaudiana. Compound 1 was shown to be 13-[(2-O-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-xylopyranosyl)oxy]ent-kaur-16-en-19-oic acid β-d-glucopyranosyl ester (rebaudioside R), while compound 2 was determined to be 13-[(2-O-α-d-glucopyranosyl-β-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid 2-O-α-l-rhamnopyranosyl-β-d-glucopyranosyl ester (rebaudioside S). Six additional known compounds were identified, dulcoside B, 13-[(2-O-β-d-xylopyranosyl-β-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid β-d-glucopyranosyl ester, eugenol diglucoside, rebaudioside G, 13-[(2-O-6-deoxy-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid β-d-glucopyranosyl ester, and rebaudioside D (3), respectively. The structures of 1 and 2 were determined based on comprehensive 1D and 2D NMR (COSY, HSQC, and HMBC) studies. A high-quality crystal of compound 3 allowed confirmation of its structure by X-ray diffraction.

  • Rebaudiosides R and S, Minor Diterpene Glycosides from the Leaves of Stevia rebaudiana
    2016
    Co-Authors: Mohamed A. Ibrahim, Douglas L. Rodenburg, Kamilla Alves, Frank R. Fronczek, Wilmer H. Perera, John Bowling, James D. Mcchesney
    Abstract:

    Two new Diterpene Glycosides have been isolated from a commercial extract of the leaves of Stevia rebaudiana. Compound 1 was shown to be 13-[(2-O-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-xylopyranosyl)­oxy]ent-kaur-16-en-19-oic acid β-d-glucopyranosyl ester (rebaudioside R), while compound 2 was determined to be 13-[(2-O-α-d-glucopyranosyl-β-d-glucopyranosyl)­oxy]ent-kaur-16-en-19-oic acid 2-O-α-l-rhamnopyranosyl-β-d-glucopyranosyl ester (rebaudioside S). Six additional known compounds were identified, dulcoside B, 13-[(2-O-β-d-xylopyranosyl-β-d-glucopyranosyl)­oxy]ent-kaur-16-en-19-oic acid β-d-glucopyranosyl ester, eugenol diglucoside, rebaudioside G, 13-[(2-O-6-deoxy-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl)­oxy]ent-kaur-16-en-19-oic acid β-d-glucopyranosyl ester, and rebaudioside D (3), respectively. The structures of 1 and 2 were determined based on comprehensive 1D and 2D NMR (COSY, HSQC, and HMBC) studies. A high-quality crystal of compound 3 allowed confirmation of its structure by X-ray diffraction

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  • Improvement of taste of natural sweeteners
    Pure and Applied Chemistry, 1997
    Co-Authors: Osamu Tanaka
    Abstract:

    Toward improvement of sweetness, studies on tnnsglycosylation of stevi- 01 gl ycosides, stevioside from Steviu rebaudinurn, rubusoside from Rubus suavisimus and their derivatives have been extensively carried out by a variety of enzyme systems. Together with rubusoside, a number of minor Diterpene Glycosides were isolated from leaves of R. suuvissimus, being significant in view of structure-taste relationship of Diterpene Glycosides of this series. Monoglucuronide of glycyrrhetinic acid (MGGR) was found to be more than 5 times sweeter than glycyrrhizin. Quantitative production of MGGR from glycyrrhizin was achieved by selective removal of the terminal glucu- ronide unit of glycyrrhizin by an enzyme from Cryprococcus magnus MG-27 (yeast).

  • Minor Diterpene Glycosides from sweet leaves of Rubus suavissimus
    Phytochemistry, 1992
    Co-Authors: Kazuhiro Ohtani, Yoko Aikawa, Ryoji Kasai, Wen-hua Chou, Kazuo Yamasaki, Osamu Tanaka
    Abstract:

    From sweet leaves of Rubus suavissimus, 10 new kaurane-type Diterpene Glycosides named suaviosides were isolated, in addition to the known major sweet glycoside, rubusoside and several known minor Glycosides. Of these minor Glycosides, suaviosides B, G, H, I and J taste sweet, and suaviosides C1, D2 and F taste bitter, while suaviosides D1 and E are tasteless. Their structures were determined mainly on the basis of NMR spectral evidence.

  • LABDANE-TYPE Diterpene Glycosides FROM FRUITS OF RUBUS-FOLIOLOSUS
    Chemical & Pharmaceutical Bulletin, 1991
    Co-Authors: Kazuhiro Ohtani, Chong-ren Yang, Chikako Miyajima, Jun Zhou, Osamu Tanaka
    Abstract:

    From fruits of Rubus foliolosus (Rosaceae), a traditional medicine used in Yunnan, China, seven labdane-type Diterpene Glycosides were isolated. Of these Glycosides, five were identified as goshonosides-F1-5 (1-5) which have been isolated from leaves of R. chingii. Structures of two new Glycosides, goshonosides-F6 (6) and -F7 (8), were elucidated as alpha-L-arabinofuranosyl-(1 --> 6)-beta-D-glucopyranoside of 13(E)-ent-labda-8(17),13-diene-3-beta,15,18-triol and 3-beta,15-di-O-beta-D-glucopyranoside of 13(E)-ent-labda-8(17),13-diene-3-beta,15-diol. Goshonosides-F6 (6) and -F7 (8) were also isolated from the leaves of R. chingii.