Kazumasa Wakamatsu

Ptaquiloside, a novel norsesquiterpene glucoside from bracken, Pteridium aquilinum var. latiusculum

An unstable norsesquiterpene glucoside with a novel illudane skeleton, ptaquiloside (1) has been isolated from bracken fern, Pteridium aquilinum var. latiusculum and the planar structure has been established on the basis of spectral and chemical means.

Ptaquiloside, a potent carcinogen isolated from bracken fern pteridiumaquilinum var. latiusculum: structure elucidation based on chemical and spectral evidence, and reactions with amino acids, nucleosides, and nucleotides

Abstract The structure of ptaquiloside (1), a potent carcinogenic compound isolated from bracken fern, Pteridium aquilinum var. latiusculum has been elucidated on the basis of chemical and spectral evidence. The dienone 3 generated from 1 under alkaline conditions was shown to be a strong alkylating agent. For the purpose of obtaining the preliminary information on chemical modification of biopolymers such as proteins and DNA with the dienone 3, reactions of 3 with amino acids, nucleosides, and nucleotides have been carried out and the alkylated products have been characterized.

Halicholactone and neohalicholactone, two novel fatty acid metabolites from the marine sponge halichondria okadai kadota

Halicholactone (1) and neohalicholactone (2), unusual fatty acid metabolites having a cyclopropane ring and a nine-membered lactone were isolated from the marine sponge Halichondria okadai Kadota. The planar structures of the new metabolites were elucidated on the basis of spectral and chemical means.

Separation of carcinogenic fraction of bracken fern

Isolation of the carcinogen in the boiling water extract of bracken fern was conducted by following the active principle with a carcinogenicity bioassay. Fractionation of the bracken extract was carried out using adsorption on resin (Amberlite XAD-2 and TOYOPEARL HW-40 (c] and organic solvent extraction. A diet containing each of the fractions was given to 7 female Charles River Sprague-Dawley rats (CD rats) of 4 weeks old, except for the second fraction. All 7 rats given the last carcinogenic fraction developed mammary and intestinal tumors and 5 rats had urinary bladder tumors. Ptaquiloside (PT) which induced mammary cancer in female CD rats and rho-hydroxystyrene glycosides were isolated from this fraction.

Stereochemistry of ptaquiloside, a novel norsesquiterpene glucoside from bracken, Pteridium aquilinum var. latiusculum

Abstract The absolute stereostructure of ptaquiloside ( 1 ), a novel norsesquiterpene glucoside isolated from bracken, Pteridium aquilinum var. latiusculum has been elucidated by the 1H NMR spectral method and an X-ray crystallographic analysis of ptaquiloside tetraacetate ( 2 ).

Hyperplastic nodules of the liver induced in rats fed bracken diet

Hyperplastic nodules (HN) of the liver were induced in Charles River Sprague-Dawley rats (CD rats) and ACI rats fed a diet containing 30% bracken for 260 and 180 days, respectively. HN were also induced in high incidence in CD rats fed a diet containing the carcinogenic fractions of bracken extract.

Synthesis of (−)-noranisatin, an oxidation product of a neurotoxic sesquiterpenoid anisatin having a novel spiro β-lactone

Abstract The synthesis of (−)-noranisatin ( 2 ), an oxidation product of anisatin ( 1 ) possessing a novel spiro β-lactone, was achieved starting from triol 5 prepared from ( R -(+)-pulegone ( 3 ).

Stereocontrolled total synthesis of (+)-tutin and (+)-asteromurin a, toxic picrotoxane sesquiterpenes

Abstract The first total synthesis of (+)-tutin ( 1 ), a toxic principle of the plants of the Coriaria species and (+)-asteromurin A ( 2 ), a bitter principle of the scale insect Asterococcus muratae KUWANA in the stereocontrolled manner is described, utilizing the epoxy olefin 10 as the common intermediate.

13C nuclear magnetic resonance studies of sesquiterpenes, anisatin and neoanisatin: The structure of anisatinic acid, a novel isomerization product of anisatin

Abstract 13 C NMR spectra are reported for derivatives of toxic sesquiterpenes, anisatin (I) and neoanisatin (II). Chemical shifts for each compound have been assigned on the basis of off-resonance decoupling experiments, known chemical shift rules, and comparison of the spectra among the compounds examined. Toxic anisatin (I) is known to isomerize under mild conditions to a non-toxic compound, anisatinic acid. The structure of anisatinic acid has been determined unambiguously to be IIIa by the 13 C NMR spectral analysis of a derivative 8 of anisatinic acid. Some aspects of the substituent effects on the 13 C chemical shifts obtained in the present investigation are described.

Stereocontrolled total synthesis of (+)-tutin, a toxic sesquiterpene of picrotoxane-type

Abstract The first total synthesis of (+)-tutin (1), a toxic sesquiterpene of picrotoxane-type isolated from the poisonous plants of the Coriaria species is described.