Tetsuya Komori

Structure of desacylsaponins obtained from the bark of Quillaja saponaria

Abstract A triterpenoid saponin mixture (so-called quillajasaponin) obtained from the bark of Quillaja saponaria was treated with weak alkali and two major desacylsaponins were isolated. On the basis of chemical and spectral evidence, they were determined as 3-O-β- D -galactopyranosyl-(1 → 2)-[β- D -xylopyranosyl-(1 → 3)]-β- D -glucuronopyranosyl quillaic acid 28-O-β- D -apiofuranosyl-(1 → 3)-β- D -xylopyranosyl-(1 → 4)-α- L -rhamnopyranosyl-(1 → 2)-β- D -fucopyranoside and 28-O-β- D -apiofuranosyl-(1 → 3)-β- D -xylopyranosyl-(1 → 4)-[β- D -glucopyranosyl-(1 → 3)]-α- L -rhamnopyranosyl-(1 → 2)-β- D -fucopyranoside. Diazomethane degradation providing selectively the 28-O-glycoside from the 3,28-O-bisglycoside was a useful method for the structure elucidation.

An acylated triterpenoid saponin from Quillaja saponaria

Abstract A new major component in the acylated triterpenoid saponin mixture (called quillajasaponin) obtained from the bark of Quillaja saponaria was isolated in a pure state. It was characterized on the basis of chemical and spectral data as 3- O -β- d -galactopyranosyl-(1 → 2)-[β- d -xylopyranosyl-(1 → 3)]-β- d -glucuronopyranosyl quillaic acid 28- O -β- d -apiofuranosyl- (1 → 3)-β- d -xylopyranosyl- (1 → 4)-[β- d -glucopyranosyl- (1 → 3)]-α- l -rhamnopyranosyl-(1 → 2)-3-[5- O -[5- O -α- l -rhamnopyranosyl-(1 → 2)-α- l -arabinofuranosyl-3,5-dihydroxy-6-methyl-octanoyl]-3,5-dihydroxy-6-methyl-octanoyl]-β- d -fucopyranoside. The diazomethane cleavage method providing selectively 28- O - glycoside from 3,28- O -bisglycoside was effective for the structure elucidation. Negative fast atom bombardment mass spectrometry was useful in providing information on the molecular weight and the structure of the complex acylated oligoglycoside.

Field desorption mass spectrometry of natural products—I: Steroid- and triterpene saponins

Field desorption mass spectra of underivatized oligoglycosides of spirostanol and its congeners and of hederagenin revealed the molecular weight and structural information. The basic predominance of the formation of stable ions of highly polar natural products (with 5–17 free OH functions) is clearly demonstrated. After the extraction and purification procedure from plant material the samples contained inorganic salts in concentrations between 0.01 and 0.1%. These salt impurities, mostly alkali halides, strongly promoted the attachment of alkali cations to the intact molecules and their fragments. The ions produced gave analytical information not only for the confirmation of the molecular weight but also for the identity of the aglycone and, to some extent, for the sequence of the sugars in the oligoglycosides. All spectra were recorded on photoplates at a resolution of better than 15000 and enabled the evaluation of the elemental composition of the ions generated. The drawbacks and merits of integrating ion recording using the photoplate for FD investigations of highly polar substances are discussed.

Flavonol glycosides in leaves of Spinacia oleracea

Abstract Besides spinatoside (3,6-dimethoxy-5,7,3′,4′-tetrahydroxyflavone 4′- O -β-D-glucopyranuronide), three new flavonol glycosides have now been isolated from the polar fractions of the methanolic extract of Spinacia oleracea . They have been identified as patuletin 3- O -β-D-glucopyranosyl-(1 → 6)-[β-D-apiofuranosyl-(1 → 2)]-β-D-glucopyranoside, patuletin 3- O -β-gentiobioside and spinacetin 3- O -β-gentiobioside, respectively.

Field desorption mass spectrometry of natural products—II1: Physiologically active pennogenin—and hederagenin-glycosides

Abstract Field desorption mass spectra of underivatized saponios, naturel oligoglycosides of physiological activity, showed intense ions formed by attachment of alkali cations to the neutral molecule and to structurally highly significant subunits. This cationization was generated by small amounts of alkali salts which were present in samples after isolation from biological material. When the mass spectre were produced by laser-supported desorption and were recorded at high resolution on vapor-deposited AgBr plates unambiguous determination of the molecular weghts (in the mass range from 700 to 1400) was performed. Moreover, ions formed by direct bond cleavages in the oligosaccharide moiety of the natural saponins clearly gave information about the sequence of the sugar units in the molecule and their individual chemical structures. The formation of these fragments in FD-MS is discussed in relation to the well established mechanism of glycosidic bond cleavage by acidic solvolysis. In principle this comparison showed the usefulness of this approach for the interpretation of FD mass spectra of substances containing heteroatom linkages e.g., glycosides, esters, amides, imines, mercaptans, etc.

Structures of compounds derived from the acyl moieties of quillajasaponin

Abstract Three compounds, an acid and two glycosidic acids, derived from the acyl moieties of quillajasaponin were obtained from the alkaline hydrolysate of the saponin mixture. On the basis of chemical and spectral evidence, they were identified as 3,5-dihydroxy-6-methyl-octanoic acid, 3,5-dihydroxy-6-methyl-octanoic acid 5- O -α- L -arabinofuranoside and 5- O -α- L -rhamnopyranosyl-(1 → 2)-α- L -arabinofuranoside. The first compound was, in fact, isolated and characterized as its lactone form. FDMS was useful in providing information on the M , of the unique acid and glycosidic acids.

Dorisenones, cytotoxic spongian diterpenoids, from the nudibranch Chromodoris obsoleta

Abstract Seven new cytotoxic spongian diterpenoids, dorisenones A ( 1 ), B ( 2 ), C ( 3 ), D ( 4 ), 7α-hydroxyspongian-16-one ( 5 ), 15α, 16α-diacetoxy-11, 12β-epoxyspongian ( 6 ) and 7α-acetoxydendrillol-3 ( 7 ) were isolated from a Japanese marine mollusk Chromodoris obsoleta (Chromodorididae), together with four known spongian diterpenoids. Their structures have been elucidated by spectroscopic evidence and single crystal X-ray analysis.

Isolation and structures of aplykurodins a and b, two new isoprenoids from the marine mollusk aplysia kurodai

Abstract Two new isoprenoids, aplykurodins A and B, were isolated from the marine mollusk, Aplysia kurodai (Aplysiidae), and their structures were determined by chemical, spectral and X-ray crystallographic analyses.

Digitalis saponins—IV : Structure of F-gitonin☆

Abstract F-gitonin, a saponin from the leaves of Digitalis purpurea L., is shown to be O-β-D-glucopyranosyl-(1→2 glc 1)-O-β-D-xylopyranosyl-(1→3glc 1)-O-β-D-glucopyranosyl-(1→4)-O-β-D-galactopyranosyl 25D, 5α-spirostane-2α,3β-diol (gitogenin β-lycotetraoside) (I) and the conjugation of lycotetraose with 3β-hydroxyl group of gitogenin is definitely proved.

ISOLATION AND STRUCTURE OF THREE NEW CERAMIDES FROM THE STARFISH ACANTHASTER PLANCI

Three new phytosphingosine-type ceramides, AC-1-6, AC-1-10 and AC-1-11, were isolated from the ceramide molecular species AC-1, obtained from the less polar fraction of the CHCl3-MeOH extract of the starfish Acanthasterplanci. The structures of these ceramides were determined on the basis of chemical and spectroscopic evidence as (2S,2′R,3S,4R,9Z)-2-(2-hydroxyhexadecanoylamino)-9-docosene-1,3,4-triol (AC-1-6), (2S,2′R,3S,4R,)-2-(2-hydroxytricosanoylamino)hexadecane-1,3,4-triol (AC-1-10) and (2S,2′R,3S,4R,)-2(2-hydroxytetracosanoylamino)hexadecane-1,3,4-triol (AC-1-11). Positive ion FABMS/MS of each ceramide gave important information for their structure elucidation. Mass spectrometry of the dimethyl disulfide derivatives of ceramide was also useful for the determination of the double bond position in the long-chain base.