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

  • a novel diterpene glycoside with nine glucose units from Stevia rebaudiana bertoni
    Biomolecules, 2017
    Co-Authors: Indra Prakash, Cynthia Bunders, Krishna Prasad Devkota, Romila D Charan, Catherine Ramirez, Tara M Snyder
    Abstract:

    Following our interest in new diterpene glycosides with better taste profiles than that of Rebaudioside M, we have recently isolated and characterized Rebaudioside IX—a novel steviol glycoside—from a commercially‐supplied extract of Stevia rebaudiana Bertoni. This molecule contains a hexasaccharide group attached at C‐13 of the central diterpene core, and contains three additional glucose units when compared with Rebaudioside M. Here we report the complete structure elucidation—based on extensive Nuclear Magnetic Resonance (NMR) analysis (1H, 13C, Correlation Spectroscopy (COSY), Heteronuclear Single Quantum Coherence‐Distortionless Enhancement Polarization Transfer (HSQC‐DEPT), Heteronuclear Multiple Bond Correlation (HMBC), 1D Total Correlation Spectroscopy (TOCSY), Nuclear Overhauser Effect Spectroscopy (NOESY)) and mass spectral data—of this novel diterpene glycoside with nine sugar moieties and containing a relatively rare 16 α‐linked glycoside. A steviol glycoside bearing nine glucose units is unprecedented in the literature, and could have an impact on the natural sweetener catalog.

  • a new diterpene glycoside 15α hydroxy rebaudioside m isolated from Stevia rebaudiana
    Natural Product Communications, 2015
    Co-Authors: Indra Prakash, Cynthia Bunders, Tara M Snyder, Krishna Prasad Devkota, Romila D Charan, Catherine Ramirez, Christopher Priedemann
    Abstract:

    : In a continued search for novel diterpenoid glycosides, we recently isolated and characterized a Rebaudioside M derivative with a hydroxyl group at position 15 in the central diterpene core from an extract of Stevia rebaudiana Bertoni. Here we report the complete structure elucidation of 15α-hydroxy-Rebaudioside M (2) on the basis of NMR (1H, 13C, COSY, HSQC-DEPT, HMBC, 1D TOCSY, NOESY) and mass spectral data. Steviol glycoside with a hydroxyl group at C-15 in the central diterpene core has not been previously reported.

  • isolation characterization and sensory evaluation of a hexa beta d glucopyranosyl diterpene from Stevia rebaudiana
    Natural Product Communications, 2013
    Co-Authors: Indra Prakash, Venkata Sai Prakash Chaturvedula, Avetik Markosyan
    Abstract:

    From the extract of the leaves of Stevia rebaudiana Bertoni, a diterpene glycoside was isolated which was identified as 13-[(2-O-beta-D-glucopyranosyl-3-O-beta-D-glucopyranosyl-beta-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-(2-O-beta-D-glucopyranosyl-3-O-beta-D-glucopyranosyl-D-glucopyranosyl) ester (1). The complete 1H and 13C NMR assignment of 1 is reported for the first time, from extensive NMR (1H and 13C, COSY, HSQC, and HMBC) and mass spectral data. Also, we report the sensory evaluation of 1 against sucrose for the sweetness property of this molecule.

  • 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.

  • 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.

Josef Caslavský - One of the best experts on this subject based on the ideXlab platform.

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

  • isolation and structure elucidation of a new diterpene glycoside from Stevia rebaudiana bertoni
    Journal of Field Robotics, 2018
    Co-Authors: Venkata Sai Prakash Chaturvedula, Srinivasa Rao Meneni
    Abstract:

    A new minor diterpene glycoside has been isolated from a commercial extract of the leaves of Stevia rebaudiana and its structure was identified as 13-[(2- O -β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent -kaur-16-en-19-oic acid-[2- O -(2- O -β-D-glucopyranosyl)-β-D-glucopyranosyl-3- O -b-D-glucopyranosyl-β-D-glucopyranosyl] ester ( 1 ) based on extensive NMR (1D and 2D) and mass spectroscopic data, and hydrolysis studies.

  • isolation and structural characterization of a new minor diterpene glycoside from Stevia rebaudiana
    Natural Product Communications, 2014
    Co-Authors: Venkata Sai Prakash Chaturvedula, Julian Zamora
    Abstract:

    : From the commercial extract of the leaves of the sweet plant Stevia rebaudiana Bertoni obtained from Sinochem Qingdao Co. Ltd., a new diterpene glycoside having three β-D-glucopyranosyl units of which two of them were connected in a relatively rare linkage of 3-β-D-glucobiosyl substitution at C-19 position of the aglycone steviol. The structure of the new compound has been characterized as 13-β-D-glucopyranosyloxy ent-kaur-16-en-19-oic acid-[(3-O-β-D- glucopyranosyl-β-D-glucopyranosyl) ester (1) on the basis of extensive 1D (1H and 13C) and 2D NMR (TOCSY, HMQC, and HMBC), and High Resolution mass spectroscopic data as well as hydrolysis studies.

  • reversed phase hplc analysis of steviol glycosides isolated from Stevia rebaudiana bertoni
    Food and Nutrition Sciences, 2014
    Co-Authors: Venkata Sai Prakash Chaturvedula, Julian Zamora
    Abstract:

    High Performance Liquid Chromatography (HPLC) experiments have been performed on nine steviol glycosides namely rebaudioside A, steviolbioside, stevioside, rubusoside, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside F, and dulcoside A isolated from the leaves of Stevia rebaudiana using Reversed-Phase (RP) column. Using RP-HPLC method, the individual retention times for nine naturally occurring ent-kaurane diterpene glycosides of S. rebaudiana reported in JECFA have been determined at four different temperatures: 20℃, 40℃, 60℃, and 79℃. Also, calculated the relative retention times of the eight steviol glycosides steviolbioside, stevioside, rubusoside, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside F, and dulcoside A against the major steviol glycoside rebaudioside A. HPLC results suggested that temperatures 40℃ and 60℃ would be ideal conditions for better separation of steviol glycosides.

  • isolation characterization and sensory evaluation of a hexa beta d glucopyranosyl diterpene from Stevia rebaudiana
    Natural Product Communications, 2013
    Co-Authors: Indra Prakash, Venkata Sai Prakash Chaturvedula, Avetik Markosyan
    Abstract:

    From the extract of the leaves of Stevia rebaudiana Bertoni, a diterpene glycoside was isolated which was identified as 13-[(2-O-beta-D-glucopyranosyl-3-O-beta-D-glucopyranosyl-beta-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-(2-O-beta-D-glucopyranosyl-3-O-beta-D-glucopyranosyl-D-glucopyranosyl) ester (1). The complete 1H and 13C NMR assignment of 1 is reported for the first time, from extensive NMR (1H and 13C, COSY, HSQC, and HMBC) and mass spectral data. Also, we report the sensory evaluation of 1 against sucrose for the sweetness property of this molecule.

  • 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.

Rema Subhash - One of the best experts on this subject based on the ideXlab platform.

  • in vitro antimicrobial activity of Stevia rebaudiana bertoni leaves
    Tropical Journal of Pharmaceutical Research, 2007
    Co-Authors: Manish Tadhani, Rema Subhash
    Abstract:

    Purpose: The aim of the present study was to investigate antimicrobial activity of the various extracts of Stevia rebaudiana leaves. Method: Stevia rebaudiana Bertoni leaves were extracted in water, methanol, ethyl acetate and hexane and their antimicrobial activities were examined against few selected microorganisms including B. subtilis, S. aureus, M. luteus, S. marcenscens, P. aeruginosa, B. megaterium, E. coli, P. vulgaris, Yeast, A. niger and R. oligoporus using cup plate method. Results: Water extract of Stevia leaf showed activity against B. subtilis and S. aureus only. Methanol extract gave the highest zone of inhibition against P. aeruginosa whereas minimum zone of inhibition was found against S. aureus and yeast. B. megaterium and yeast were found to be highly susceptible towards ethyl acetate and hexane extracts, respectively whereas A. niger and B. subtilis were found to be least susceptible against ethyl acetate and hexane extracts, respectively. Hexane extract showed the highest activity against yeast among the tested microorganisms. Conclusion: The study confirms the possible antimicrobial potentiality of the leaf extract of Stevia rebaudiana.

  • in vitro antioxidant activities of Stevia rebaudiana leaves and callus
    Journal of Food Composition and Analysis, 2007
    Co-Authors: Manish Tadhani, Vinayak Patel, Rema Subhash
    Abstract:

    Abstract Leaf extract of Stevia rebaudiana promotes effects on certain physiological systems such as the cardiovascular and renal and influences hypertension and hyperglycemia. Since these activities may be correlated with the presence of antioxidant compounds, leaf and callus extracts of Stevia rebaudiana were evaluated for their total phenols, flavonoids content and total antioxidant capacity. Total phenols and flavonoids were analyzed according to the Folin–Ciocalteu method and total antioxidant activity of water and methanolic extracts of Stevia leaves and callus was assessed by ferric reducing/antioxidant power (FRAP) assay as well as 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The total phenolic compounds were found to be 25.18 mg/g for Stevia leaves and 35.86 mg/g for callus on dry weight basis. The flavonoids content was found to be 21.73 and 31.99 mg/g in the leaf and callus, respectively. The total antioxidant activity was expressed as mg equivalent of gallic acid, ascorbic acid, BHA and trolox per gram on dry weight basis. Total antioxidant activity found was ranged from 9.66 to 38.24 mg and 11.03 to 36.40 mg equivalent to different standards in water and methanolic extract of Stevia leaves, respectively. In case of Stevia callus, it was found to be 9.44 to 37.36 mg for water extract and 10.14 to 34.37 mg equivalent to standards for methanolic extract. The concentrations required for 50% inhibition (IC50) of DPPH radicals were 11.04, 41.04 and 57.14 μg/mL for gallic acid, trolox and butylated hydroxyanisole (BHA), respectively. The percent inhibition of DPPH radical of various extracts of Stevia leaves and callus found were ranged from 33.17% to 56.82%. The highest percent of inhibition was observed in methanolic extract of callus.

Manish Tadhani - One of the best experts on this subject based on the ideXlab platform.

  • in vitro antimicrobial activity of Stevia rebaudiana bertoni leaves
    Tropical Journal of Pharmaceutical Research, 2007
    Co-Authors: Manish Tadhani, Rema Subhash
    Abstract:

    Purpose: The aim of the present study was to investigate antimicrobial activity of the various extracts of Stevia rebaudiana leaves. Method: Stevia rebaudiana Bertoni leaves were extracted in water, methanol, ethyl acetate and hexane and their antimicrobial activities were examined against few selected microorganisms including B. subtilis, S. aureus, M. luteus, S. marcenscens, P. aeruginosa, B. megaterium, E. coli, P. vulgaris, Yeast, A. niger and R. oligoporus using cup plate method. Results: Water extract of Stevia leaf showed activity against B. subtilis and S. aureus only. Methanol extract gave the highest zone of inhibition against P. aeruginosa whereas minimum zone of inhibition was found against S. aureus and yeast. B. megaterium and yeast were found to be highly susceptible towards ethyl acetate and hexane extracts, respectively whereas A. niger and B. subtilis were found to be least susceptible against ethyl acetate and hexane extracts, respectively. Hexane extract showed the highest activity against yeast among the tested microorganisms. Conclusion: The study confirms the possible antimicrobial potentiality of the leaf extract of Stevia rebaudiana.

  • in vitro antioxidant activities of Stevia rebaudiana leaves and callus
    Journal of Food Composition and Analysis, 2007
    Co-Authors: Manish Tadhani, Vinayak Patel, Rema Subhash
    Abstract:

    Abstract Leaf extract of Stevia rebaudiana promotes effects on certain physiological systems such as the cardiovascular and renal and influences hypertension and hyperglycemia. Since these activities may be correlated with the presence of antioxidant compounds, leaf and callus extracts of Stevia rebaudiana were evaluated for their total phenols, flavonoids content and total antioxidant capacity. Total phenols and flavonoids were analyzed according to the Folin–Ciocalteu method and total antioxidant activity of water and methanolic extracts of Stevia leaves and callus was assessed by ferric reducing/antioxidant power (FRAP) assay as well as 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The total phenolic compounds were found to be 25.18 mg/g for Stevia leaves and 35.86 mg/g for callus on dry weight basis. The flavonoids content was found to be 21.73 and 31.99 mg/g in the leaf and callus, respectively. The total antioxidant activity was expressed as mg equivalent of gallic acid, ascorbic acid, BHA and trolox per gram on dry weight basis. Total antioxidant activity found was ranged from 9.66 to 38.24 mg and 11.03 to 36.40 mg equivalent to different standards in water and methanolic extract of Stevia leaves, respectively. In case of Stevia callus, it was found to be 9.44 to 37.36 mg for water extract and 10.14 to 34.37 mg equivalent to standards for methanolic extract. The concentrations required for 50% inhibition (IC50) of DPPH radicals were 11.04, 41.04 and 57.14 μg/mL for gallic acid, trolox and butylated hydroxyanisole (BHA), respectively. The percent inhibition of DPPH radical of various extracts of Stevia leaves and callus found were ranged from 33.17% to 56.82%. The highest percent of inhibition was observed in methanolic extract of callus.