Hideki Tosa

Antibacterial Activity of Xanthones from Guttiferaeous Plants against Methicillin-resistant Staphylococcus aureus

Extracts of Garcinia mangostana (Guttiferae) showing inhibitory effects against the growth of S. aureus NIHJ 209p were fractionated according to guidance obtained from bioassay and some of the components with activity against methicillin‐resistant Staphylococcus aureus (MRSA) were characterized.

A xanthone from pericarps of Garcinia mangostana

A new xanthone with a geranyl group, mangostinone, was isolated from pericarps of Garcinia mangostana, in addition to seven known xanthones, α-, β- and γ-mangostins, gartanin, garcinone E, 1,5-dihydroxy-2-(3-methylbut-2-enyl)-3-methoxy- and 1,7-dihydroxy-2-(3-methylbut-2-enyl)-3-methoxyxanthone. The structures were determined by means of spectroscopic analysis.

Two xanthones from root bark of Calophyllum inophyllum

Two new xanthones, named caloxanthones A and B, were isolated from the root bark of Calophyllum inophyllum, in addition to known xanthones (macluraxanthone and 1,5-dihydroxyxanthone) and (−)-epicatechin. Their structures were determined by spectroscopic analysis, in particular, by 2D NMR techniques.

Two prenylated anthrones in Harungana madagascariensis

Abstract Two new anthrones were isolated from Harungana madagascariensis in addition to a known anthrone, two xanthones, four anthraquinones and two flavonoids. The structures of the two anthrones were determined to be 1,3,8-trihydroxy-4,5-diisoprenyl-7-methylanthrone (harunganol A) and 1,3,8-trihydroxy-4,5,7-triisoprenyl-7-methylanthrone (harunganol B) by spectroscopic analysis. The other anthrone, 1,8-dihydroxy-2-isoprenyl-3-methoxy-6-methylanthrone which has been once derived from natural product, and one xanthone, 1,5,6-trihydroxy-7-methyxyxanthone which has been synthesized earlier were isolated for the first time as genuine natural products.

Two Xanthones from Roots of Calophyllum inophyllum.

Abstract From the root bark of Calophyllum inophyllum, a new xanthone named caloxanthone D and from the root heartwood, another new xanthone, caloxanthone E, in addition to four known xanthones [1,3,8-trihydroxy-7-methoxy-, 1,3-dihydroxy-7,8-methoxy-, 1,3,5-trihydroxy-2-methoxy- and 6-hydroxy-1,5-dimethoxy-] were isolated. The structures were determined by analysis of NMR spectral data including 2D techniques.

A flavone from leaves of Arrabidaea chica f. cuprea

Abstract A new flavone, 6,7,3′,4′-tetrahydroxy-5-methoxyflavone, named carajuflavone, was isolated from the leaves of the Brazilian plant Arrabidaea chica f. cuprea . The structure was established by spectroscopic analysis.

Two New Xanthones in the Underground Part of Calophyllum inophyllum.

From the root bark of Calophyllum inophyllum L. (Guttiferae), a new xanthone named caloxanthone C (1) and 4-hydroxyxanthone (2), and from the heartwood of root, a new xanthone 1-hydroxy-2-methoxyxanthone (3) in addition to three known xanthones [1,2-dimethoxy-(4), 2-hydroxy- 1-methoxy-(5)], and 6-deoxyjacareubin (6) were isolated. The structures were characterized by means of a spectroscopic analysis

Six xanthones from Calophyllum austroindicum

Abstract Six new xanthones, caloxanthone F, G, H, 6-hydroxy-1,3,5-trimethoxy-, 3,6-dihydroxy-1,5-dimethoxy- and 1,3,6-trihydroxy-5,7-dimethoxyxanthone, were isolated from the stem wood of Calophyllum austroindicum , in addition to eight known xanthones. From the bark, four known xanthones, a coumarin, apetallic acid, and (−)-epicatechin were isolated. These structures were determined by analysis of NMR spectral data including 2D techniques.

Two xanthones from roots of Cratoxylum formosanum

From the roots of Cratoxylum formosanum, two new xanthones, 2,7-dihydroxy-1,8-dimethoxyxanthone and 1,4,7-trihydroxy-8-methoxyxanthone, were isolated, in addition to seven known xanthones and two flavonoids. Among the xanthones, 1,4,7-trihydroxyxanthone was the first isolation from the natural sources. Structures were determined by spectral analyses.

Prenylated xanthonoids from Calophyllum apetalum

Abstract Three new xanthonoids, apetalinones A-C, were isolated from the roots of Calophyllum apetalum, as well as the known compounds, calozeyloxanthone and zeyloxanthonone. The stem bark of this species yielded a new xanthonoid, apetalinone D, and another known xanthonoid, tomentonone. Five known xanthones (3,8-dihydroxy-1,2-dimethoxy-, 1,3-dihydroxy-2,5-dimethoxy-, 1,5-dihydroxy-, 1,3,5-trihydroxy-2-methoxy- and 1,3,5-trihydroxyxanthone) and two flavonoids ((−)-epiafzelechin and (−)-epicatechin) were also characterized as constituents in the stem wood. Among them, apetalinone A was a novel xanthone with 1,1-dimethylallyl ether moiety, which indicated a new biosynthetic pathway including Claisen rearrangement and Diels-Alder reaction.