Kazuhiro Ohtani

Steroidal saponins from fruits of Tribulus terrestris

Further studies on the constituents of the fruits of Tribulus terrestris led to the isolation of five new steroidal saponins (terrestrosin A-E), (25R,S)-5 alpha-spirostan-3 beta-ol-3 -O-beta-D-galactopyranosyl(1-2)-beta-D- glucopyranosyl(1-4)-beta-D-galactopyranoside, (25R,S)-5 alpha-spirostan-3 beta-ol-3-O-beta-D-glucopyranosyl(1-4)-[alpha-L- rhamnopyranosyl(1-2)]-beta-D-galactopyranoside, (25R,S)-5 alpha-spirostan-12-on-3 beta-ol-3-O-beta-D-galactopyranosyl (1-2)-beta-D-glucopyranosyl(1-4)-beta-D-galactopyranoside, hecogenin 3-O-beta-D-galactopyranosyl)1-2)-[beta-D- xylopyranosyl(1-3)]-beta-D-glucopyranosyl(1-4)-beta-D-galactopyranoside and (25R,S)-5 alpha-spirostane-2 alpha, 3 beta-diol-3- O-beta-D-galactopyranosyl(1-2)-beta-D-glucopyranosyl(1-4)-beta-D- galactopyranoside, together with five known steroidal saponins, desgalactotigonin, F-gitonin, desglucolanatigonin, gitonin and tigogenin 3-O-beta-D- xylopyranosyl)1-2)-[beta-D-xylopyranosyl)1-3)]-beta-D-glucopyranosyl)1-4 )- [alpha-L-rhamnopyranosyl(1-2)]-beta-D-galactopyranoside. The structures of the new saponins were elucidated on the basis of spectroscopic analyses, including two-dimensional NMR techniques, and chemical reactions.

Antihistaminic flavones and aliphatic glycosides from Mentha spicata

Abstract The ethyl acetate soluble portion of the methanol extract of Mentha spicata var. crispa showed inhibitory activity on exocytosis in antigen-stimulated rat basophils. The bioassay-guided separation of the components of this fraction afforded 13 compounds. The chemical structures were elucidated to be four known flavonoids, three new and five known glucosides of lower alcohls and rosmarinic acid by means of chemical and spectroscopic evidences. Among them, three compounds showed biological activity. From the non-active 1-butanol soluble portion of the methanol extract, four new and two known structurally related glycosides were isolated and characterized.

Dammarane-type triterpenoid saponins from Bacopa monniera

Three new dammarane-type triterpenoid saponins, bacopasaponins A, B and C, of biological interest have been isolated from the reputed Indian medicinal plant Bacopa monniera and identified as 3-O-alpha-L-arabinopyranosyl-20-O-alpha-L-arabinopyranosyl-+ ++jujubogenin, 3-O-[alpha-L-arabinofuranosyl (1--> 2)alpha-L-arabinopyranosyl]pseudojujubogenin and 3-O-[beta-D-glucopyranosyl (1 -->3)[alpha-L-arabinofuranosyl (1--> 2)]alpha-L-arabinopyranosyl]pseudojujubogenin by spectroscopic methods and some chemical transformations. The hitherto undetermined configurations at C-20 and C-22 of pseudojujubogenin were elucidated by phase-sensitive ROESY, and 1H and 13C signals of the saponins were assigned by DEPT, 1H-1H COSY, HSQC and HMBC techniques.

Minor diterpene glycosides from sweet leaves of Rubus suavissimus

From sweet leaves of Rubus suavissimus, 10 new kaurane-type diterpene glycosides named suaviosides were isolated, in addition to the known major sweet glycoside, rubusoside and several known minor glycosides. Of these minor glycosides, suaviosides B, G, H, I and J taste sweet, and suaviosides C1, D2 and F taste bitter, while suaviosides D1 and E are tasteless. Their structures were determined mainly on the basis of NMR spectral evidence.

Revised structure for hortensin, a flavonoid from Millingtonia hortensis

Abstract The original structure of hortensin, from Millingtonia hortensis , and analysed as 4′-hydroxy-6,7-dimethoxyflavonol, has been changed once to 5,4′-dihydroxy-6,7-dimethoxyflavone (cirsimaritin). A further reinterpretation of the NMR data of newly isolated ‘hortensin’ showed that it is 5,7-dihydroxy-6,4′-dimethoxyflavone (pectolinarigenin). Several related flavonoids from the same plant were also identified.

Iridoid and megastigmane glycosides from Phlomis aurea

From the leaves of Phlomis aurea, two new iridoids of unique structures named 3-epiphlomurin (1) and phlomurin (2), a new megastigmane glucoside phlomuroside (3) and a new benzyl alcohol glycoside having the structure benzyl alcohol-O-beta-xylopyranosyl-(1-->2)-beta-glucopyranoside (4) have been isolated together with four known iridoids auroside, lamiide, 8-epiloganin and ipolamiide, two known phenolic glycosides acteoside (verbascoside) and syringin, one known phenylethanoid glycoside 2-phenylethyl-O-beta-xylopyranosyl-(1-->2)-beta-glucopyranoside, one known lignan liriodendrin and three known flavonoids chrysoeriol-7-O-beta-glucopyranoside, acacetin-7-O-beta-glucopyranoside and luteolin-7-O-beta-glucopyranoside. The structures of the isolated compounds were verified by means of mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectral analyses.

Lignan glycosides from stems of Salvadora persica

Abstract From stems of Salvadora persica , five glycosides were isolated. Two are new and identified as sodium 1- O -benzyl-β- d -glucopyranoside-2-sulphate (salvadoside) and 5,5′-dimethoxylariciresinol 4,4′bis- O -β- d -glucopyranoside (salvadoraside), in addition to syringin, liriodendrin and sitosterol 3- O -glucopyranoside. This represents the first report of syringin and lignan glycosides from the family Salvadoraceae.

Bacopasaponin D-A pseudojujubogenin glycoside from Bacopa monniera

A new dammarane-type pseudojujubogenin glycoside, bacopasaponin D, has been isolated from the reputed Indian medicinal plant Bacopa monniera and defined as 3-O-[alpha-L-arabinofuranosyl(I-->2)beta-D-glucopyranosyl]pseudojujub ogenin by spectroscopic methods and some chemical transformations. The 13C signals of the saponin were assigned by DEPT, 1H-1H COSY and HSQC techniques.

Neolignan glycosides from roots of Codonopsis tangshen.

The isolation and strucutral determination of tangshenosides III and IV, new neolignan glycosides, and four hexenyl and hexyl glycosides from the roots of Codonopsis tangshen are reported.

Oleanane saponins from Polyscias fruticosa

From the leaves and roots of Polyscias fruticosa, eight new oleanolic acid saponins named polysciosides A to H were isolated together with three known saponins. The structures of the saponins were established by means of spectral data, particularly NMR, which included COSY, HSQC, HMBC, HOHAHA and ROESY techniques.