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Open AccessArticle

Four New ent-Kaurane Diterpene Glycosides from Isodon henryi

by Ya-Lin Liu, Ling-Xia Zhang, Hong Wu, Sui-Qing Chen, Jun Li, Li-Ping Dai and Zhi-Min Wang

Molecules 2019, 24(15), 2736; https://doi.org/10.3390/molecules24152736 - 27 Jul 2019

Cited by 9 | Viewed by 2967

To obtain diterpene glycosides from an aqueous extract of the aerial parts of Isodon henryi and further investigate their cytotoxicities, in this study, a total of seven compounds were isolated, including six ent-kaurane diterpene glycosides (1–6) and one [...] Read more.

To obtain diterpene glycosides from an aqueous extract of the aerial parts of Isodon henryi and further investigate their cytotoxicities, in this study, a total of seven compounds were isolated, including six ent-kaurane diterpene glycosides (1–6) and one diterpene aglycon (7). Among the seven ent-kaurane diterpenes obtained, four were novel compounds, including ent-7,20-epoxy- kaur-16-en-1α,6β,7β,15β-tetrahydroxyl-11-O-β-d-glucopyranoside (1), ent-7,20-epoxy-kaur-16-en- 6β,7β,14β,15β-tetrahydroxyl-1-O-β-d-glucopyranoside (2), ent-7,20-epoxy-kaur-16-en-6β,7β,15β- trihydroxyl-1-O-β-d-glucopyranoside (3), and ent-7,20-epoxy-kaur-16-en-7β,11β,14α,15β-tetrahydr- oxyl-6-O-β-d-glucopyranoside (4), and three were isolated from this plant for the first time (5–7). Their structures were elucidated by utilizing spectroscopic methods and electronic circular dichroism analyses. Furthermore, the cytotoxicities of all seven compounds were investigated in four human cancer cell lines, including A2780, BGC-823, HCT-116, and HepG2. The IC₅₀ values of these diterpenes ranged from 0.18 to 2.44 mM in the tested cell lines. In addition, the structure–cytotoxicity relationship of diterpene glycosides was also evaluated to study the effect of glycosylation on the cytotoxicity of diterpene compounds. Full article

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9 pages, 1186 KB

Open AccessArticle

New Ent-Kaurane-Type Diterpene Glycosides and Benzophenone from Ranunculus muricatus Linn.

by Bi-Ling Wu, Hui-Liang Zou, Fang-Min Qin, Hong-Yu Li and Guang-Xiong Zhou

Molecules 2015, 20(12), 22445-22453; https://doi.org/10.3390/molecules201219801 - 15 Dec 2015

Cited by 11 | Viewed by 5378

Abstract

Two new ent-kaurane diterpene glycosides, ranunculosides A (1) and B (2), and a new benzophenone, ranunculone C (3), were isolated from the aerial part of Ranunculus muricatus Linn. The chemical structures of compounds 1–3 [...] Read more.

Two new ent-kaurane diterpene glycosides, ranunculosides A (1) and B (2), and a new benzophenone, ranunculone C (3), were isolated from the aerial part of Ranunculus muricatus Linn. The chemical structures of compounds 1–3 were established to be (2S)-ent-kauran-2β-ol-15-en-14-O-β-d-glucopyranoside, (2S,4S)-ent-kauran-2β,18-diol-15-en-14-O-β-d-glucopyranoside, and (R)-3-[2-(3,4-dihydroxybenzoyl)-4,5-dihydroxy-phenyl]-2-hydroxylpropanoic acid, respectively, by spectroscopic data and chemical methods. The absolute configuration of 1 was determined by the combinational application of RP-HPLC analysis and Mosher’s method. Full article

(This article belongs to the Section Molecular Diversity)

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12 pages, 971 KB

Open AccessArticle

Hydrogenation of the Exocyclic Olefinic Bond at C-16/C-17 Position of ent-Kaurane Diterpene Glycosides of Stevia rebaudiana Using Various Catalysts

by Venkata Sai Prakash Chaturvedula and Indra Prakash

Int. J. Mol. Sci. 2013, 14(8), 15669-15680; https://doi.org/10.3390/ijms140815669 - 26 Jul 2013

Cited by 3 | Viewed by 6645

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, [...] Read more.

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. Full article

(This article belongs to the Section Biochemistry)

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11 pages, 284 KB

Open AccessArticle

Catalytic Hydrogenation of the Sweet Principles of Stevia rebaudiana, Rebaudioside B, Rebaudioside C, and Rebaudioside D and Sensory Evaluation of Their Reduced Derivatives

by Indra Prakash, Mary Campbell and Venkata Sai Prakash Chaturvedula

Int. J. Mol. Sci. 2012, 13(11), 15126-15136; https://doi.org/10.3390/ijms131115126 - 16 Nov 2012

Cited by 30 | Viewed by 8662

Abstract

Catalytic hydrogenation of rebaudioside B, rebaudioside C, and rebaudioside D; the three ent-kaurane diterpene glycosides isolated from Stevia rebaudiana was carried out using Pd(OH)₂. Reduction of steviol glycosides was performed using straightforward synthetic chemistry with the catalyst Pd(OH)₂ and [...] Read more.

Catalytic hydrogenation of rebaudioside B, rebaudioside C, and rebaudioside D; the three ent-kaurane diterpene glycosides isolated from Stevia rebaudiana was carried out using Pd(OH)₂. Reduction of steviol glycosides was performed using straightforward synthetic chemistry with the catalyst Pd(OH)₂ and structures of the corresponding dihydro derivatives were characterized on the basis of 1D and 2D nuclear magnetic resonance (NMR) spectral data indicating that all are novel compounds being reported for the first time. Also, the taste properties of all reduced compounds were evaluated against their corresponding original steviol glycosides and sucrose. Full article

(This article belongs to the Section Biochemistry)

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9 pages, 230 KB

Open AccessArticle

Synthesis and Sensory Evaluation of ent-Kaurane Diterpene Glycosides

by Indra Prakash, Mary Campbell, Rafael Ignacio San Miguel and Venkata Sai Prakash Chaturvedula

Molecules 2012, 17(8), 8908-8916; https://doi.org/10.3390/molecules17088908 - 26 Jul 2012

Cited by 18 | Viewed by 9350

Abstract

Catalytic hydrogenation of the three ent-kaurane diterpene glycosides isolated from Stevia rebaudiana, namely rubusoside, stevioside, and rebaudioside-A has been carried out using Pd(OH)₂ and their corresponding dihydro derivatives have been isolated as the products. Synthesis of reduced steviol glycosides was [...] Read more.

Catalytic hydrogenation of the three ent-kaurane diterpene glycosides isolated from Stevia rebaudiana, namely rubusoside, stevioside, and rebaudioside-A has been carried out using Pd(OH)₂ and their corresponding dihydro derivatives have been isolated as the products. 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 and chemical studies. Also, we report herewith the sensory evaluation of all the reduced compounds against their corresponding original steviol glycosides and sucrose for the sweetness property of these molecules. Full article

(This article belongs to the Special Issue Advances in Carbohydrate Chemistry 2012)

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8 pages, 464 KB

Open AccessArticle

Synthesis of ent-Kaurane Diterpene Monoglycosides

by Venkata Sai Prakash Chaturvedula, Josef Klucik, Mani Upreti and Indra Prakash

Molecules 2011, 16(10), 8402-8409; https://doi.org/10.3390/molecules16108402 - 3 Oct 2011

Cited by 24 | Viewed by 8824

Abstract

Synthesis of two ent-kaurane diterpene glycosides, steviol 19-O-β-D-glucopyranosiduronic acid (steviol glucuronide, 5), and 13-hydroxy ent-kaur-16-en-19-oic acid-β-D-glucopyranosyl ester (7) has been achieved from a common starting material, steviol, using phase transfer catalyst. Also, synthesis of an additional 17-nor-ent [...] Read more.

Synthesis of two ent-kaurane diterpene glycosides, steviol 19-O-β-D-glucopyranosiduronic acid (steviol glucuronide, 5), and 13-hydroxy ent-kaur-16-en-19-oic acid-β-D-glucopyranosyl ester (7) has been achieved from a common starting material, steviol, using phase transfer catalyst. Also, synthesis of an additional 17-nor-ent-kaurane glycoside, namely 13-methyl-16-oxo-17-nor-ent-kauran-19-oic acid-β-D-glucopyranosyl ester (10) was performed using the starting material isosteviol and similar synthetic methodology. Synthesis of all three steviol glycosides was performed using straightforward chemistry and their structures were characterized on the basis of 1D and 2D NMR as well as mass spectral (MS) data. Full article

(This article belongs to the Special Issue Terpenoids)

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11 pages, 278 KB

Open AccessArticle

Diterpene Glycosides from Stevia rebaudiana

by Venkata Sai Prakash Chaturvedula, Mani Upreti and Indra Prakash

Molecules 2011, 16(5), 3552-3562; https://doi.org/10.3390/molecules16053552 - 28 Apr 2011

Cited by 60 | Viewed by 11560

Abstract

Three novel diterpene glycosides were isolated for the first time from the commercial extract of the leaves of Stevia rebaudiana, along with several known steviol glycosides, namely stevioside, rebaudiosides A-F, rubusoside and dulcoside A. The new compounds were identified as 13-[(2-O [...] Read more.

Three novel diterpene glycosides were isolated for the first time from the commercial extract of the leaves of Stevia rebaudiana, along with several known steviol glycosides, namely stevioside, rebaudiosides A-F, rubusoside and dulcoside A. The new compounds were identified as 13-[(2-O-β-D-glucopyranosyl-3-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-15-en-19-oic acid (1), 13-[(2-O-β-D-glucopyranosyl-3-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy]-16β-hydroxy-ent-kauran-19-oic acid (2) and 13-methyl-16-oxo-17-nor-ent-kauran-19-oic acid-β-D-glucopyranosyl ester (3) on the basis of extensive 2D NMR and MS spectroscopic data as well as chemical studies. Full article

(This article belongs to the Section Natural Products Chemistry)

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29 pages, 171 KB

Open AccessReview

Occurrence, Biological Activities and Synthesis of Kaurane Diterpenes and their Glycosides

by Pablo Anselmo Garcia, Alaide Braga De Oliveira and Ronan Batista

Molecules 2007, 12(3), 455-483; https://doi.org/10.3390/12030455 - 13 Mar 2007

Cited by 133 | Viewed by 18248

Abstract

This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria [...] Read more.

This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kauranediterpenes are presented, focusing on their chemical structures, occurrence in the plant kingdom and their main, recently described, biological activities. Moreover, the most significant works, published between 1964 and November 2006, which describe the total synthesis or structural transformations of some kaurane diterpenes, including either semisynthetic and/or microbiologicalmethodologies, are consisely reviewed. At this point, some general considerations on glycosides are introduced, and kaurane glycosides are presented and discussed on the basis of their toxic importance and occurrence in the plant kingdom, having focused on related aspects of their biological activities and the relationships between these activities and the structural factors of their molecules. Finally, the principal methods of glycosidation byenzymatic and chemical processes are both presented, and a few papers on the synthesis of kaurane glycosides are succinctly discussed. Full article

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