New megastigmane glucosides from Excoecaria cochinchinensis LOUR. var. cochinchinensis

Two new megastigmane glucosides, called excoecariosides A and B were isolated from the leaves of a medicinal Vietnamese plant, Excoecaria cochinchinensis LOUR. var. cochinchinensis (Euphorbiaceae) together with seven known compounds. Their structures were elucidated by spectroscopic analyses and chemical reactions including the modified Mosher's method.     

Tricalysiosides P-U: Ent-kaurane glucosides and a labdane glucoside from leaves of Tricalysia dubia OHWI

Further extensive isolation work on the 1-BuOH-soluble fraction of a MeOH extract of Tricalysia dubia afforded five new ent-kaurane glucosides (4-8) and one new labdane glucoside (9), together with a known megastigmane glucoside, sammangaoside B (1), and monoterpene glucosides (2, 3). The structures of the new compounds were elucidated by analyses of one- and two-dimensional NMR spectroscopic data. The absolute configuration of the 9-position of sammangaoside B was revised to S and its total stereochemistry was established by the modified Mosher's method.     

Terpenic and phenolic glycosides from leaves of Breynia officinalis HEMSL

From the leaves of Breynia officinalis, collected on Okinawa Island, six terpenic glucosides and six phenolic glycosides were isolated. Two of the terpenic glucosides were found to be known, and they were identified as turpinionoside B and betulalbuside A. The structures of the remaining terpenic glucosides were elucidated to be megastigmane glucosides, named breyniaionosides A-D, using spectroscopic analyses. The absolute structure of breyniaionoside D was determined using the modifed Mosher's method. The absolute structure of the known compound betulalbuside A was determined for the first time in this study. Six phenolic glycosides were found to be arbutin and its derivatives. Two known compounds were found to be robustaside A and eximine. New compounds were named isorobustaside A, and breyniosides A and B, and their structures were elucidated from spectroscopic evidence.     

Radical-scavenging activities of new megastigmane glucosides from Macaranga tanarius (L.) MULL.-ARG

Four new megastigmane glucosides, named macarangiosides A-D (2-5), together with mallophenol B, lauroside E, methyl brevifolin carboxylate, and hyperin and isoquercitrin as a mixture were isolated from the leaves of Macaranga tanarius (L.) MULL.-ARG. (Euphorbiaceae). Their structures were elucidated by spectroscopic and chemical analyses. Macarangioside A-C (2-4) and mallophenol B were galloylated on glucose moiety and possessed the potent 2,2-diphenyl-picrylhydrazyl (DPPH) radical-scavenging activity.     

Iridoid glucosides from Veronica hederifolia

A new iridoid glucoside, urphoside A, and six known iridoid glucosides, pikuroside, aucubin, veronicoside, catalposide, amphicoside, and verminoside, were isolated from Veronica hederifolia together with a known megastigmane glucoside, 3-hydroxy-5,6-epoxy-beta-ionol-9-O-beta-D-glucopyranoside, and a hexitol, dulcitol. The structures of the isolated compounds were established by the extensive 1D- and 2D-NMR spectroscopy.     

5,11-Epoxymegastigmanes from the leaves of Asclepias fruticosa)

Five new megastigmane glucosides and one of their aglycones were isolated, along with (6S,9R)-roseoside, from the polar fraction of the leaves of Asclepias fruticosa, and the structures were determined by spectroscopic methods. Most of them have an epoxy-linkage between C-5 and C-11. The configurations at C-3 and C-9 for each compound were confirmed to be S and R, respectively, by application of the modified Mosher's method.     

Two New Diterpenoid Glucosides from Clerodendrathus spicatus

Two new diterpenoid glucosides, clerodendranthusides B and C ( 1 and 2 , resp.), together with 16 known compounds, comprising four lignans, five miscellaneous phenylpropanoids, two flavonoids, one sesquiterpenoid glycoside, two triterpenoid glycosides, one megastigmane, as well as one anthraquinone, were isolated from the 50% EtOH extract of the whole plants of Clerodendrathus spicatus. Their structures were elucidated by chemical and spectroscopic methods.     

Glochidionionosides A-D: megastigmane glucosides from leaves of Glochidion zeylanicum (Gaertn.) A. Juss

Five megastigmane glucosides were isolated from the leaves of Glochidion zeylanicum. One of them was a known compound, blumenol C O-beta-D-glucopyranoside (1), and the structures of the four new compounds, glochidionionosides A-D (2-5), were mainly elucidated by spectroscopic methods, including a modified Mosher's method. The absolute configurations of the six-membered ring of glochidionionoside D (5) were deduced by beta-D-glucopyranosylation-induced shift trends in the (13)C-NMR spectra and confirmed by X-ray analysis as its p-bromobenzoate (5b), and the axis chirality of C-7 was determined to be R.     

Tricalysionoside A, a megastigmane gentiobioside, sulfatricalysines A-F, and tricalysiosides X-Z, ent-kaurane glucosides, from the leaves of Tricalysia dubia

Further isolation work on the water-soluble fraction of a MeOH extract of Tricalysia dubia afforded one new megastigmane gentiobioside, named tricalysionoside A (1), and three sulfates, named sulfatricalysines A-C (2-4). Extensive isolation work on the 1-BuOH-soluble fraction of a MeOH extract of T. dubia yielded sulfatricalysines D-F (5-7) and three new ent-kaurane glucosides, named tricalysiosides X-Z (8-10). The structures of the new compounds were elucidated by analyses of one- and two-dimensional NMR spectroscopic data. The absolute stereochemistry of tricalysionoside A (1) was established by modified Mosher's method.     

Turpinionosides A-E: megastigmane glucosides from leaves of Turpinia ternata Nakai

From leaves of Turpenia ternata (Staphylaceae), one megastigmane and seven of its glucosides (1-8) were isolated. Megastigmane and two of the glucosides were found to be known compounds, namely, 3S,5R,6R,9S-tetrahydroxymegastigmane (1), corchoionoside C (2), and icariside B4 (3). The structures of compounds 4-8 (turpinionosides A-E, respectively) were elucidated by means of spectroscopic analyses, and then their absolute structures were determined by the modified Mosher's method to be (3S,5R,6S,9S)-3,6,9-trihydroxymegastigman-7-ene 3-O- and 9-O-beta-D-glucopyranosides (4, 5, respectively), (1S,3S,5R,6S,9R)-3,9,12-trihydroxymegastigmane 3-O-beta-D-glucopyranoside (6), (3S,4R,9R)-3,4,6-trihydroxymegastigman-5-ene 3-O-beta-D-glucopyranoside (7), and (2S,9R)-2,9-dihydroxymegastigman-5-en-4-one 2-O-beta-D-glucopyranoside (8).     

Megastigmane, benzyl and phenethyl alcohol glycosides, and 4,4'-dimethoxy-beta-truxinic acid catalpol diester from the leaves of Premna subscandens MERR

Extensive isolation work on the n-BuOH-soluble fraction obtained from the leaves of Premna subscandens, collected on Ishigaki island, Okinawa, afforded six compounds. Two were identified as megastigmane glucosides, 7-(3,5-dihydroxy-1,1,5-trimethylcyclohexylidene)-9-methylprop++ +-8-enyl 9-O-beta-D-glucopyranoside and 3-hydroxy-5,6-epoxy-beta-ionol 9-O-beta-D-glucopyranoside. The structures of the remaining four new compounds were elucidated to be a 2'-O-beta-D-apiofuranosyl derivative of 3-hydroxy-5,6-epoxy-beta-ionol 9-O-beta-D-glucopyranoside, named premnaionoside, benzyl alcohol beta-D-(2'-O-beta-D-xylopyranosyl)glucopyranoside, phenethyl alcohol beta-D-(2'-O-beta-D-glucopyranosyl)glucopyranoside, and 4,4'-dimethoxy-beta-truxinic acid catalpol diester by spectroscopic analyses.     

Debilosides A–C: Three New Megastigmane Glucosides from Equisetum debile

Debilosides A–C ( 1 – 3 ), three new megastigmane glucosides, were isolated from the whole plant of Equisetum debile, together with the four known constituents blumenol A, corchoinoside C, sammangaoside A, and (3S,5R,6R,7E,9S)‐9‐[(β‐D ‐glucopyranosyl)oxy]megastigm‐7‐ene‐3,5,6‐triol ( 4 ). Their structures were elucidated on the basis of in‐depth spectroscopic analyses including 2D‐NMR techniques.     

Reinvestigation of the absolute stereochemistry of megastigmane glucoside, icariside B(5)

Icariside B(5) is one of the widely distributed megastigmane glucosides among plant sources. The absolute structure of icariside B(5) was reinvestigated by chemical conversion from the related compound and the application of the modified Mosher's method. As a result, the structure of icariside B(5) was revised to be (6S,9S)-6,9-dihydroxymegastigman-4-en-3-one 9-O-β-D-glucopyranoside.     

Two new megastigmanes from the leaves of Cucumis sativus

Two new megastigmane, cucumegastigmanes I (1) and II (2), together with a known megastigmane, (+)-dehydrovomifoliol (3), and five other known compounds were isolated from the leaves of Cucumis sativus. The structures of the new compounds were elucidated from spectroscopic analysis and their absolute stereochemistries were determined in detail using the chemical conversion and a modified Mosher's method.     

Myrsinionosides A-E: megastigmane glycosides from the leaves of Myrsine seguinii Lev

Eight megastigmane glycosides were isolated from the leaves of Myrsine seguinii collected in Okinawa. Three of them were found to be known compounds, i.e., ampelopsisionoside, alangionoside J, and linarionoside A. The structures of the new megastigmane glycosides were elucidated from the spectroscopic data and their absolute stereochemistries were determined in detail using a modified Mosher's method.     

Conduritol F glucosides and terpenoid glucosides from Cynanchum liukiuense and distribution of conduritol F glucosides in several Asclepiadaceous plants

Conduritol F 3-0- and 4-O-glucosides were obtained from Cynanchum liukiuense, along with conduritol F which was identified in all Asclepiadaceous plants examined, Tylophora tanakae, Asclepias curassavica and A. fruticosa, as well as in Marsdenia tomentosa. The pattern of the glucosidic linkage to conduritol F differed between individual species, 2-O-glucoside from T tanakae and M. tomentosa, 3-O-glucoside from A. curassavica, but none from A. fruticosa. Along with conduritol F glucosides, an 11-glucosyloxy-megastigmane and a monoterpenoid glucoside were isolated from C. liukiuense.     

A new 5,11-epoxymegastigmane glucoside from Acanthus ilicifolius

From a China mangrove plant Acanthus ilicifolius Linn., a new compound, 5,11-epoxymegastigmane glucoside (1) was isolated along with one known compound of megastigmane glucosides, (6S, 9S)-roseoside (2). The structure of compound 1 was determined on the basis of 1D- and 2D-NMR techniques (DEPT, COSY, HMBC, HMQC, NOESY) and HR-FABMS. The structure of 1 was established as (1S, 3S, 5R, 6R, 7E)-5,11-epoxy-3-hydroxymegastigman-7-en-9-one-3-O-beta-D-glucopyranoside.     

A monoterpene glucoside and three megastigmane glycosides from Juniperus communis var. depressa

A new monoterpene glucoside (1) and three new natural megastigmane glycosides (2-4) were isolated along with a known megastigmane glucoside (5) from twigs with leaves of Juniperus communis var. depressa (Cupressaceae) collected in Oregon, U.S.A., and their structures were determined on the basis of spectral and chemical evidence. In addition, the antibacterial activities of the isolated components against Helicobacter pylori were also investigated.     

New megastigmane glycoside and aromadendrane derivative from the aerial part of Piper elongatum

A new megastigmane glycoside, called pipeloside A, and a new aromadendrane type sesquiterpenoid, pipelol A, were isolated from the MeOH extract of the aerial part of Piper elongatum VAHL. along with a known megastigmane glycoside, byzantionoside B. The structures of these compounds were elucidated on the basis of spectroscopic data and chemical evidence.     

New megastigmane and tetraketide from the leaves of Euscaphis japonica

New megastigmane (1) and tetraketide (2) were isolated from the leaves of Euscaphis japonica and the structures were elucidated by means of spectroscopic and chemical evidence.