Masami Ishibashi

Purealidins B and C, new bromotyrosine alkaloids from the okinawan marine sponge Psammaplysilla purea

New bromotyrosine-derived alkaloids, purealidins B (1) and C (2), have been isolated from the Okinawan marine sponge Psammaplysilla purea and their structures elucidated on the basis of spectroscopic data. Purealidin B (1) showed antibacterial activity, while purealidin C (2) exhibited antifungal and antineoplastic activities.

Penaresidin A and B, two novel azetidine alkaloids with potent actomyosin ATPase-activating activity from the Okinawan marine sponge Penares sp.

Two novel sphingosine-derived azetidine alkaloids, penaresidin A, 1a, and B, 1b, were isolated as potent actomyosin ATPase activators from the Okinawan marine sponge Penares sp. and the structures elucidated on the basis of spectral data, especially two-dimensional NMR spectra of their acetates.

Hyrtiosins A and B, new indole alkaloids from the Okinawan marine sponge Hyrtios erecta

Abstract Two new indole alkaloids, hyrtiosins A (2) and B (3), together with known 5-hydroxyindole-3-aldehyde (1) have been isolated from the Okinawan marine sponge Hyrtios erecta and their structures elucidated on the basis of the spectroscopic data.

Iejimalides C and D, new antineoplastic 24-membered macrolide sulfates from the okinawan marine tunicate Eudistoma cf. rigida

Abstract Two new 24-membered macrolide sulfates, iejimalides C ( 1 ) and D ( 2 ), with antineoplastic activity have been isolated from the Okinawan marine tunicate Eudistoma cf. rigida . The structures were elucidated on the basis of spectroscopic data.

Rigidin, a novel alkaloid with calmodulin antagonistic activity from the okinawan marine tunicate Eudistoma CF. rigida

Abstract A novel pyrrolopyrimidine alkaloid, rigidin ( 1 ), with calmodulin antagonistic activity has been isolated from the Okinawan marine tunicate Eudistoma cf. rigida . The structure was elucidated on the basis of spectral data of 1 and its pentamethyl derivative ( 2 ).

Convolutamides A ∼ F, novel γ-lactam alkaloids from the marine bryozoan Amathia convoluta

Abstract Convolutamides A ∼ F, new alkaloids containing an N-acyl-γ-lactam moiety with a dibromophenol group, have been isolated from the Floridian bryozoan Amathia convoluta and the structures elucidated on the basis of spectroscopic data.

Colopsinol A, a Novel Polyhydroxyl Metabolite from Marine Dinoflagellate Amphidinium sp.

Colopsinol A (1), a novel polyhydroxyl compound, has been isolated from the cultured marine dinoflagellate Amphidinium sp., from which a number of cytotoxic macrolides, amphidinolides, have been obtained to date, and the gross structure of 1 was elucidated on the basis of extensive spectroscopic analyses including recent 2D NMR techniques of CH(2)-selected editing HSQC as well as FABMS/MS experiments and chemical means. Colopsinol A (1), C(71)H(119)O(25)SNa, is the first member of a new class of polyketide natural products possessing a gentiobioside moiety and a sulfate ester. The polyketide aglycon consisted of a C(56)-linear aliphatic chain with one exo-methylene and two methyl branches as well as two ketones, five hydroxyl groups, and a tetrahydropyran and two epoxide rings.

Luteophanols B and C, new polyhydroxyl compounds from marine dinoflagellate Amphidinium sp.

Abstract Luteophanols B (1) and C (2), new polyhydroxyl linear carbon-chain compounds, have been isolated from the cultured marine dinoflagellate Amphidinium sp. The structures of 1 and 2 were elucidated by detailed analyses of two-dimensional NMR data containing HMBC, HMQC-RELAY, CH2-selected E-HSQC, and CH2-selected E-HSQC-TOCSY.

Untenone A, a new cyclopentenone from the Okinawan marine sponge Plakortis sp. corresponding to the dienophile in the biosynthesis of manzamenones

Untenone A (1), a new cyclopentenone derivative was isolated from the Okinawan marine sponge Plakortis sp. This compound (1) is chemically equivalent to the hypothetical dienophile in biosynthesis of manzamenones and this isolation provides a substantiation for the proposed biosynthetic process of manzamenones involving intermolecular [4+2] cycloaddition reaction.

Revised structures of prianosins C and D, antineoplastic alkaloids from the Okinawan marine sponge Prianos melanos

The structures of prianosins C and D, antineoplastic alkaloids isolated from the Okinawan marine sponge Prianos melanos, have been revised to be 1 and 2, respectively, on the basis of comparison of the spectral data with those of 2-hydroxydiscorhabdin D and discorhabdin D, respectively.