Ent-kaurane Diterpene Glycosides Research Articles

Four New ent-Kaurane Diterpene Glycosides from Isodon henryi.

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.

A New ent-kaurane Diterpene Glycoside from Seeds of Pharbitis nil

A new ent-kaurane diterpene glycoside, pharboside H (1), and three known compounds, benzyl β-D-glucopyranoside (2), 1-(4′-O-glucopyranosyl-4′-hydroxy-3′,5′-dimethoxyphenyl)-2{2′′,6′′-dimethoxy-4′′-[1-(E) propen-3-ol]-phenoxy}-propane-l,3-diol (3), and butyl caffeate (4), were isolated from the seeds of Pharbitis nil. The structure of the new compound 1 was elucidated by 1D and 2D data analysis and enzyme hydrolysis. All the isolated compounds 1–4 were reported from this source for the first time. Compounds 1–4 were tested for cytotoxicity against four human tumor cell lines in vitro using the sulforhodamine B bioassay.

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

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.

Two new ent-kaurane-type diterpene glycosides from zucchini (Cucurbita pepo L.) seeds

Two new ent-kaurane diterpene glycosides; 12α-(β-d-glucopyranosyloxy)-7β-hydroxykaurenolide (1) and 7β-(β-d-glucopyranosyloxy)-12α-hydroxykaurenolide (2), a new steroid; (24S)-stigmasta-7,22E,25-trien-3-one (12), and known compounds (3–11, 13–14) were isolated from zucchini (Cucurbita pepo L.) seeds. The absolute structures of 1 and 2 were determined by acid hydrolysis and application of a modified Moscher's method. Furthermore, isolated compounds (1–14), and a derivative, 1a, were evaluated for their inhibitory effects on macrophage activation by an inhibitory assay of nitric oxide (NO) production.

Reversed-phase HPLC analysis studies of the sweet diterpene glycosides isolated from Stevia rebaudiana Bertoni

High Performance Liquid Chromatography (HPLC) studies were performed on the nine sweet steviol glycosides reported in Joint Expert Committee on Food Additives (JECFA) 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) HPLC method, individual retention times and area for nine naturally occurring ent-kaurane diterpene glycosides of S. rebaudiana have been determined at various temperatures from 20 °C to 79 °C. HPLC results suggested that temperatures between 40 °C and 60 °C would be ideal conditions for better separation of steviol glycosides. Additional HPLC studies at five different temperatures 40 °C, 45 °C, 50 °C, 55 °C, and 60 °C under three different pH 2.4, 2.6, and 2.8 were performed and results suggested that temperatures 50 °C and 55 °C at pH 2.4 would be ideal condition for better separation of steviol glycosides.

Constituents of Vigna angularis and their in vitro anti-inflammatory activity

Nine non-phenolic compounds, including four furanylmethyl glycosides, angularides A–D, one ent-kaurane diterpene glycoside, angularin A, and four triterpenoid saponins, angulasaponins A–D, were isolated from seeds of Vigna angularis, together with eight known compounds. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic analysis as well as chemical methods. Angularin A, angulasaponins A–C, and azukisaponins III and VI showed inhibition of nitric oxide production in LPS-activated RAW264.7 macrophages, with IC50 values ranging from 13μM to 24μM.

Reversed-Phase HPLC Analysis of Steviol Glycosides Isolated from Stevia rebaudiana Bertoni

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 and Structural Characterization of a New Minor Penta β-D-Glucopyranosyl Diterpene from Stevia rebaudiana Bertoni

From the commercial extract of the leaves of Stevia rebaudiana Bertoni, a new minor ent-kaurane diterpene glycoside having five β-D-glucopyranosyl units has been isolated. The chemical structure of the new compound was characterized as 13-[(2-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-(2-O-β-D-glucopyranosyl-6-O-β-D-glucopyranosyl-β-D-glucopyranosyl) ester (1) on the basis of extensive 1D (1H & 13C) and 2D NMR (TOCSY, HMQC, and HMBC), and High Resolution (HR) mass spectroscopic data as well as hydrolysis studies.

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

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.

A new isoflavane glycoside from Cicer arietinum seeds

A new isoflavane glycoside with a novel structure that we called cicerarietinuoside A (1) in addition to the three known compounds β-daucosterol (2), adenosine (3), and ent-kaurane diterpene glycoside (4) were isolated from seeds of chickpea. Their structures were established based on broad spectral analysis. Compounds 2 and 4 were obtained from chickpea seeds for the first time.

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

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.

Synthesis and Sensory Evaluation of ent-Kaurane Diterpene Glycosides

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.

IR Spectral Analysis of Diterpene Glycosides Isolated from <i>Stevia rebaudiana</i>

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.

Synthesis of ent-Kaurane Diterpene Monoglycosides

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.

Neolignans and ent-Labdane Diterpenoid from the Leaves of Casearia sylvestris (Flacourtiaceae)

Casearia sylvestris Swartz (Flacourtiaceae) is a Brazilian and Paraguayan folk medicinal plant called as „Guaçatonga“ or „Chá de Bugre“ and is used to treat snakebite, trauma, ulceration, obesity, and cough [1–5]. Our continued investigation of this species to look for new chemotaxonomic markers has led to the isolation of six new neolignans, casearialignans A-F (1–6) and a new ent-labdane glycoside sylvestin (7) as well as a known lignan glycoside syringaresinol-β-D-glucoside. Compounds 1–6 possessed a 3-(3,5-dimethoxyphenyl)-1,2-propanediol structural moiety. To the best of our knowledge, this is the first time to report the 8-O-4′ type neolignans with such a structure mioety. Therefore, this type of 8-O-4′ neolignans might be considered as chemotaxonomic marker of the title plant. Compound 7 is the first and the only ent-labadane diterpene glycoside found in the title plant. Since many ent-kaurane diterpene glycosides coexist in the same plant [6,7], 1 might be considered as a biosynthetic precursor of the ent-kaurane derivatives.

Diterpene Glycosides from the Seeds of Pharbitis nil

Six new ent-kaurane diterpene glycosides, pharbosides A-F (1-6), and a new ent-gibbane diterpene glycoside, pharboside G (7), together with three known ent-kaurane diterpenoids, 7beta,16beta,17-trihydroxy-ent-kauran-6alpha,19-olide (8), 6beta,7beta,16alpha,17-tetrahydroxy-ent-kauranoic acid (9), and 6beta,7beta,16beta,17-tetrahydroxy-ent-kauranoic acid (10), were isolated from an ethanolic extract of the seeds of Pharbitis nil. The structures of the new compounds were determined by spectroscopic methods including 1D and 2D NMR analysis. The absolute configurations of the compounds were clarified by CD spectroscopic studies. Full NMR data assignments of the three known compounds (8-10) are reported. The isolated compounds were evaluated for their cytotoxic activities against four human cancer cell lines.

Chemical constituents of Pithecellobium albicans

A new ent-kaurane diterpene glycoside identified as (-)19-beta-D-glucopyranosyl 6,7-dihydroxy kaurenoate, was isolated from the seeds of Pithecellobium albicans. The structure of the new compound was established by spectral data.

A New ent‐Kaurane Diterpenoid Glycoside from the Leaves of Cussonia bojeri, a Malagasy Endemic Plant.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A New ent-Kaurane Diterpenoid Glycoside from the Leaves of Cussonia bojeri, a Malagasy Endemic Plant.

A new ent-kaurane diterpene glycoside, beta-D-glucopyranosyl 17-hydroxy-ent-kauran-19-oate-16-O-beta-D-glucopyranoside (4) was isolated from the dried leaves of Cussonia bojeri SEEM., together with four known compounds identified as 16beta,17-dihydroxy-kauran-19-oic acid (1), beta-D-glucopyranosyl 16beta,17-dihydroxy-(-)-kauran-19-oate (2), paniculoside IV (3), and rutin (5). The structure of 4 was deduced on the basis of chemical and spectroscopic evidence.