Clerodane and labdane diterpene glycosides from a Malagasy endemic plant,Cussonia racemosa

Four clerodane glycosides, cussosides A-D, and one labdane glycoside, cussoside E were isolated from the dried leaves of Cussonia racemosa, along with two known flavonol glycosides identified as rutin and kaempferol rutinoside. The structures of the compounds were deduced on the basis of their physical and spectral data.     

Ornithosaponins A-D, four new polyoxygenated steroidal glycosides from the bulbs of Ornithogalumthyrsoides

By analyzing the steroidal glycoside content of fresh bulbs of Ornithogalum thyrsoides (Liliaceae), we were able to isolate four new polyoxygenated steroidal glycosides, which we named ornithosaponins A-D (1-4). The structures of 1-4 were elucidated on the basis of extensive spectroscopic analysis, including that of 2D NMR data, and the results of acidic or alkaline hydrolysis. The aglycone structure of 1-4 has not been previously reported. It is also notable that ornithosaponins B-D (2-4) have been found to contain 6-deoxy-beta-D-gulopyranose as a sugar component, which is rarely encountered in plant glycosides.     

nor-Oleanene type triterpene glycosides from the leaves of Acanthopanax japonicus

Three new (1-3) and two known (4-5) triterpene glycosides were isolated from the leaves of Acanthopanax japonicus (Araliaceae) and elucidated structurally by mass, 1D, and 2D NMR spectroscopy. All the compounds possessed a nor-oleanene triterpene skeleton as the aglycone. The structures of 1-5 were established as 28-O-alpha-L-rhamno-pyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester of 3beta-hydroxy- 30-nor-olean-12,20(29)-diene-23,28-dioic acid, designated as acanjaposide A, 3beta- hydroxy-23-oxo-30-nor-olean-12,20(29)-diene-28-oic acid, named acanjaposide B, 3beta,20alpha-dihydroxy-23-oxo-30-nor-olean-12-en-28-oic acid, named acanjaposide C, and nipponoside E, a known saponin, respectively.     

Ent-kaurane glycosides and sesquiterpene lactones of the hirsutinolide type from Vernonia triflosculosa

Investigation of the aerial parts of Vernonia triflosculosa afforded three hirsutinolides of which 8alpha-(4alpha-hydroxymethacryloyloxy)-10alpha-hydroxy-1,13-dimethoxy-hirsutinolide is new, three ent-kaurane diterpenes, among which the 19-[alpha-L-arabinopyranosyl-(1-->2)-beta-D-glucopyranosyl] esters of 16beta-hydroxy-ent-kauran-19-oic acid and of 16beta,17-hydroxy-ent-kauran-19-oic acid are also new. Diterpenes are reported here for the first time in the large genus Vernonia. Their structures were elucidated using 1D and 2D NMR measurement as well as ESI, CIMS, and HRMS analysis. Two hirsutinolides were studied for their NF-kappaB DNA binding activity in HaCaT cells (a human cell line similar to keratinocytes) and for their inhibition on IL-8 production in HeLa cells.     

Leishmanicidal cycloartane-type triterpene glycosides from Astragalus oleifolius

Two new cycloartane-type glycosides oleifoliosides A (1) and B (2) were isolated from the lower stem parts of Astragalus oleifolius. Their structures were identified as 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-xylopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane and 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane, respectively, by means of spectroscopic methods (IR, 1D and 2D NMR, ESI-MS). Three known cycloartane glycosides cyclocanthoside E (3), astragaloside II (4) and astragaloside IV (5) were also isolated and characterized. All five compounds were evaluated for in vitro trypanocidal, leishmanicidal and antiplasmodial activities as well as their cytotoxic potential on primary mammalian (L6) cells. Except for the compound 5, all compounds showed notable growth inhibitory activity against Leishmania donovani with IC50 values ranging from 13.2 to 21.3 microg/ml. Only weak activity against Trypanosoma brucei rhodesiense was observed with the known compounds astragaloside II (4, IC50 66.6 microg/ml) and cyclocanthoside E (3, IC50 85.2 microg/ml), while all compounds were inactive against Trypanosoma cruzi and Plasmodium falciparum. None of the compounds were toxic to mammalian cells (IC50's > 90 microg/ml). This is the first report of leishmanicidal and trypanocidal activity of cycloartane-type triterpene glycosides.     

Monoterpene glycosides isolated from Fadogia agrestis

Six monoterpene glycosides were isolated from Fadogia agrestis. Their structures were elucidated using a combination of mass spectroscopy, 1D- and 2D-homo- and hetero-NMR spectroscopy and chemical analysis, and established as being derivatives of 2,6-dimethyl-2(E),6(Z)-octadiene-1,8-diol containing from two to four units of rhamnopyranose and, three of them, one or two additional units of glucopyranose. In three of the compounds an acyl group of 8-hydroxy-2,6-dimethyl-2(E),6(Z)-octadienoyl was found esterifying the O-2 position of one of the units of rhamnopyranose.     

Acylated pregnane glycosides from Caralluma russeliana

The chloroform extract of the aerial parts of Caralluma russeliana yielded four acylated pregnane glycosides, namely russeliosides E-H, three were found now. The structures of the compounds were elucidated using MS, 1H NMR, 13C NMR, 1H-1H COSY, HMQC, NOESY and HMBC experiments.     

Steroidal glycosides from Ruscus ponticus

A comparative metabolite profiling of the underground parts and leaves of Ruscus ponticus was obtained by an HPLC-ESIMSⁿ method, based on high-performance liquid chromatography coupled to electrospray positive ionization multistage ion trap mass spectrometry. The careful study of HPLC-ESIMSⁿ fragmentation pattern of each chromatographic peak, in particular the identification of diagnostic product ions, allowed us to get a rapid screening of saponins belonging to different classes, such as dehydrated/or not furostanol, spirostanol and pregnane glycosides, and to promptly highlight similarities and differences between the two plant parts. This approach, followed by isolation and structure elucidation by 1D- and 2D-NMR experiments, led to the identification of eleven saponins from the underground parts, of which two dehydrated furostanol glycosides and one new vespertilin derivative, and nine saponins from R. ponticus leaves, never reported previously. The achieved results highlighted a clean prevalence of furostanol glycoside derivatives in R. ponticus leaves rather in the underground parts of the plant, which showed a wider structure variety. In particular, the occurrence of dehydrated furostanol derivatives, for the first time isolated from a Ruscus species, is an unusual finding which makes unique the saponins profile of R. ponticus.     

Acetylated phenolic glycosides from Harpagophytum procumbens

Two acetyl phenolic glycosides, 6-acetylacteoside and 2,6-diacetylacteoside, were obtained from commercially available secondary roots of Harpagophytum procumbens and were identified using spectroscopic methods.     

Minor diterpenoid glycosides from the leaves of Stevia rebaudiana

From the commercial extract of the leaves of Stevia rebaudiana, three new diterpenoid glycosides were isolated besides eight known steviol glycosides including stevioside, rebaudiosides A–F and dulcoside A. The structures of the three compounds were identified as 13-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]-kaur-16-en-18-oic acid-(6-O-β-d-xylopyranosyl-β-d-glucopyranosyl) ester (1), 13-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]-17-hydroxy-kaur-15-en-18-oic acid β-d-glucopyranosyl ester (2), and 13-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]-17-oxo-kaur-15-en-18-oic acid β-d-glucopyranosyl ester (3) on the basis of extensive NMR and MS spectral studies. Another known diterpenoid glycoside, 13-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]-kaur-15-en-18-oic acid β-d-glucopyranosyl ester (4) was also isolated and its complete NMR spectral assignments were made on the basis of COSY, HSQC and HMBC spectral data.     

Caucasicosides E-M, furostanol glycosides from Helleborus caucasicus

Nine furostanol glycosides, namely caucasicosides E-M, were isolated from the MeOH extract of the leaves of Helleborus caucasicus, along with 11 known compounds including nine furostanol glycosides, a bufadienolide and an ecdysteroid. Their structures were established by the extensive use of 1D and 2D NMR experiments along with ESIMSⁿ analyses. The steroidal composition of leaves of H. caucasicus shows as particular feature the occurrence of steroidal compounds belonging to the 5β series, unusual for Helleborus species, and in particular, caucasicosides F-H are based on a 5β-polyhydroxylated steroidal aglycon never reported before.     

Acylated flavone glycosides from Veronica

A survey of the flavonoid glycosides of selected taxa in the genus Veronica yielded two new acylated 5,6,7,3',4'-pentahydroxyflavone (6-hydroxyluteolin) glycosides and two unusual allose-containing acylated 5,7,8,4'-tetrahydroxyflavone (isoscutellarein) glycosides. The new compounds were isolated from V. liwanensis and V. longifolia and identified using NMR spectroscopy as 6-hydroxyluteolin 4'-methyl ether 7-O-alpha-rhamnopyranosyl(1"'-->2")[6"-O-acetyl-beta-glucopyranoside] and 6-hydroxyluteolin 7-O-(6"-O-(E)-caffeoyl)-beta-glucopyranoside, respectively. Isoscutellarein 7-O-(6"'-O-acetyl)-beta-allopyranosyl(1"'-->2")-beta-glucopyranoside was obtained from both V. intercedens and V. orientalis and its 4'-methyl ether from V. orientalis only. Complete 1H and 13C NMR spectral assignments are presented for both isoscutellarein glycosides. Two iridoid glucosides new to the genus Veronica (melittoside and globularifolin) were also isolated from V. intercedens.     

New glycosides of the campesterol derivative from the rhizomes of Tacca chantrieri

Seven new glycosides of the campesterol derivative (24R,25S)-ergost-5-ene-3beta,26-diol (1-7) were isolated from the rhizomes of Tacca chantrieri (Taccaceae). Their structures were determined by extensive spectroscopic analysis, including 2D NMR data, and a few chemical transformations.     

New pregnane glycosides from Caralluma dalzielii

Twenty-seven new pregnane glycosides were isolated from the whole plant of Caralluma dalzielii, and their structures elucidated from extensive 2D NMR analysis as well as ESI-MS experiments. All isolated compounds were tested for their antiproliferative activity on J774.A1, HEK-293, and WEHI-164 cell lines. Moderate to high potency of cytotoxicities were found in almost all tested compounds, confirming the significant cytotoxic activity of pregnane glycosides.     

Acylated phenolic glycosides from Solenostemma argel

From the aerial parts of Solenostemma argel, four new acylated phenolic glycosides sinapyl alcohol 9-O-feruloyl-4-O-alpha-rhamnopyranosyl-(1-->2)-beta-glucopyranoside, solargin I (1), sinapyl alcohol 9-O-caffeoyl-4-O-alpha-rhamnopyranosyl-(1-->2)-beta-glucopyranoside, solargin II (2), sinapyl alcohol 9-O-feruloyl-4-O-alpha-rhamnopyranosyl-(1-->2)-alpha-rhamnopyranosyl-(1-->2)-beta-glucopyranoside, solargin III (3) and sinapyl alcohol 9-O-caffeoyl-4-O-alpha-rhamnopyranosyl-(1-->2)-alpha-rhamnopyranosyl-(1-->2)-beta-glucopyranoside, solargin IV (4) have been isolated. The structures of the isolated compounds were verified by means of MS and NMR spectral analyses.     

ent-Labdane glycosides from the aquatic plant Potamogeton lucens and analytical evaluation of the lipophilic extract constituents of various Potamogeton species

Two new ent-labdane glycosides, one known furano-ent-labdane and a new hydroxylated fatty acid were isolated from the dichloromethane extract of the freshwater aquatic plant Potamogeton lucens. The new compounds were assigned the structures of beta-d-glucopyranosyl-8(17),13-ent-labdadien-16,15-olid-18-oate, 18-beta-d-glucopyranosyloxy-8(17),13-ent-labdadien-16,15-olide and 13(R)-hydroxy-octadeca-(9Z,11E,15Z)-trien-oic acid by spectroscopic means. The algicidal activity of these compounds was tested against Raphidocelis subcapitata. Based on our previous study of Potamogeton pectinatus, other constituents were identified in P. lucens by LC-UV-MS, LC-NMR and GC-MS. The lipophilic extract profiles of both species are presented. Two other species, Potamogeton perfoliatus and P. crispus, were also investigated by analytical comparison of their non-polar extracts. The distribution of ent-labdanes characterized in Potamogeton is summarized.     

Acylated flavonoid and phenylethanoid glycosides from Marrubium velutinum

From the aerial parts of Marrubium velutinum, one acylated flavonoid glycoside, chrysoeriol 7-O-(3",6"-di-O-E-p-coumaroyl)-beta-D-glucopyranoside, and two tetrasaccharidic phenylethanoid glycosides, velutinosides I-II, have been isolated together with ten known flavonoids and seven known phenylethanoid glycosides. The structures of the isolated compounds were established by means of NMR, MS, and UV spectral analyses.     

Acylated flavonol glycosides as probing stimulants of a bean aphid,Megoura crassicauda,from Vicia angustifolia

A bean aphid, Megoura crassicauda, which feeds selectively on the plant genus Vicia (Fabaceae), was found to be stimulated to probe an extract solution of the host plant, narrowleaf vetch, Vicia angustifolia L., depositing characteristic stylet sheaths on a parafilm membrane. Two acylated flavonol glycosides were isolated as the specific probing stimulants from the extracts and characterized as quercetin 3-O-alpha-L-arabinopyranosyl-(1-->6)-[2"-O-(E)-p-coumaroyl]-beta-D-glucopyranoside and quercetin 3-O-alpha-L-arabinopyranosyl-(1-->6)-[2"-O-(E)-p-coumaroyl]-beta-D-galactopyranoside. A mixture of these compounds in the same equivalency strongly induced the probing response from M. crassicauda, suggesting their kairomonal roles during host recognition.     

Flavonoid glycosides from Salvia moorcroftiana wall

Phytochemical analysis of the whole plant of Salvia moorcroftiana Wall. (Lamiaceae) resulted in the isolation of two new flavonoid glycosides, together with three known compounds. The structures of the new compounds were established as genkwanin 4'-O-alpha-L-arabinopyranosyl-(1-->6)-beta-D-galactopyranoside (1) and genkwanin 4'-O-[alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->6)]-beta-D-galactopyranoside] (2). The structures of all compounds were elucidated by spectroscopic methods, including 2D NMR techniques.