Naonobu Tanaka

Tomoeones A–H, cytotoxic phloroglucinol derivatives from Hypericum ascyron

Phloroglucinol derivatives tomoeones A-H (1-8) and three known compounds were isolated from leaves of Hypericum ascyron. Their structures were established based on spectroscopic analyses. They are all acylphloroglucinol derivatives possessing a spiro skeleton with geminal isoprenyl groups and a monoterpene moiety, and they are stereoisomers to each other at C-4 and C-13. They appear to be a class of phloroglucinol derivatives. Cytotoxicities of the isolated phloroglucinol derivatives against human tumor cell lines, including multidrug-resistant (MDR) cancer cell lines, were evaluated. Tomoeone F (6) demonstrated significant cytotoxicity against KB cells with an IC50 value of 6.2 microM. Compound 6 was also cytotoxic against MDR cancer cell lines (KB-C2 and K562/Adr), which was more potent than doxorubicin.

Acylphloroglucinol, biyouyanagiol, biyouyanagin B, and related spiro-lactones from Hypericum chinense.

Biyouyanagiol (1), an acylphloroglucinol-related compound having a unique cyclopenta-1,3-dione moiety, was isolated from a Japanese traditional medicinal plant, Hypericum chinense, together with three new spiro-lactone-related derivatives, biyouyanagin B (2), 5,6-dihydrohyperolactone D (3), and 4-hydroxyhyperolactone D (4). Their structures were established on the basis of spectroscopic evidence. In a cytotoxicity assay against human cancer cell lines including multidrug-resistant (MDR) cancer cell lines, several compounds demonstrated enhanced cytotoxicity against MDR KB cells in the presence of colchicine.

Hyrtimomines A–C, New Heteroaromatic Alkaloids from a Sponge Hyrtios sp.

Three new alkaloids, hyrtimomines A-C (1-3), were isolated from an Okinawan marine sponge Hyrtios sp. The structures of 1-3 were elucidated on the basis of spectroscopic analysis and application of a phenylglycine methyl ester (PGME) method. Hyrtimomines A (1) and B (2) are heteroaromatic alkaloids possessing a fused hexacyclic 6/5/6/6/7/5 ring system, while hyrtimomine C (3) is an alkaloid consisting of hydroxyindole and azepino-hydroxyindole moieties. Hyrtimomine A (1) exhibited cytotoxicity against KB and L1210 cells.

Chromone and chromanone glucosides from Hypericum sikokumontanum and their anti-Helicobacter pylori activities

Chromone glucosides, takanechromones A-C (1, 2 and 5) and chromanone glucosides, named takanechromanones A and B (3 and 4), were isolated from the methanolic extracts of Hypericumsikokumontanum together with 27 known compounds. Their structures were established based on spectroscopic evidence. The isolated compounds and some chromone derivatives were assayed for antimicrobial activity against Helicobacter pylori and cytotoxicity against human cancer cell lines.

Xanthones from Hypericum chinense and their cytotoxicity evaluation.

A xanthonolignoid, 2-O-demethylkielcorin, and a phenylxanthone, chinexanthone A, were isolated from stems of Hypericum chinense together with four known xanthonolignoids and seven known xanthones. Their structures were established by spectroscopic analysis, as their optical properties and absolute stereochemistry determined. The cytotoxicities of the isolated xanthone derivatives as well as additional 32 xanthones against a panel of human cancer cell lines were also evaluated.

Nagelamides X–Z, Dimeric Bromopyrrole Alkaloids from a Marine Sponge Agelas sp.

Three new dimeric bromopyrrole alkaloids, nagelamides X-Z (1-3), were isolated from a marine sponge Agelas sp. Nagelamides X (1) and Y (2) possess a novel tricyclic skeleton consisting of spiro-bonded tetrahydrobenzaminoimidazole and aminoimidazolidine moieties. Nagelamide Z (3) is the first dimeric bromopyrrole alkaloid involving the C-8 position in dimerization. The structures of 1-3 were elucidated on the basis of spectroscopic data. Nagelamides X-Z (1-3) exhibited antimicrobial activity.

Prenylated acylphloroglucinols, chipericumins A-D, from Hypericum chinense.

Two new tetracyclic prenylated acylphloroglucinols, chipericumins A (1) and B (2), were isolated from the roots of Hypericum chinense, together with two new tricyclic prenylated acylphloroglucinols, chipericumins C (3) and D (4). Their structures were elucidated by spectroscopic data. Chipericumins A-D (1-4) are prenylated acylphloroglucinols having a spiro skeleton with an acyl group, a methyl group, a C(5) unit, and a monoterpene moiety in common.

Biyoulactones A-C, new pentacyclic meroterpenoids from Hypericum chinense.

Three novel pentacyclic meroterpenoids with a unique dilactone structure containing C-C bonded bi- and tricyclic γ-lactone moieties, biyoulactones A-C (1-3), were isolated from the roots of Hypericum chinense, and their structures were elucidated on the basis of spectroscopic data. The relative and absolute stereochemistry of 1 was assigned by a combination of NOESY and a single crystal X-ray diffraction analysis.

Agelamadins A and B, dimeric bromopyrrole alkaloids from a marine sponge Agelas sp.

Two structurally unique dimeric bromopyrrole alkaloids, agelamadins A (1) and B (2), were isolated from a marine sponge Agelas sp. Agelamadins A (1) and B (2) have a structure consisting of an agelastatin-like tetracyclic moiety and an oroidin-like linear moiety in common. The structures of 1 and 2 were elucidated on the basis of spectroscopic analysis. The antimicrobial activity and cytotoxicity of agelamadins A (1) and B (2) were evaluated.

Petiolins A-C, phloroglucinol derivatives from Hypericum pseudopetiolatum var. kiusianum

Two new phloroglucinol derivatives possessing chromane skeleton, petiolins A (1) and B (2), and a new phloroglucinol derivative containing a dihydrofuran ring, petiolin C (3), were isolated from aerial parts of Hypericum pseudopetiolatum var. kiusianum. The gross structures of 1-3 were elucidated by spectroscopic data, and the relative stereochemistry of 3 was elucidated by NOESY data. Petiolins A-C (1-3) showed modest cytotoxicity, while petiolin C (3) exhibited antifungal activity.