Hiroshi Hirota

Haliclamines a and B, cytotoxic macrocyclic alkaloids from a sponge of the genus Haliclona

Abstract Two cytotoxic alkaloids, haliclamines A and B, have been isolated from a sponge Haliclona sp., and their structures were elucidated mainly by spectroscopic analyses including extensive 2D NMR experiments.

Two sesquiterpene isocyanides and a sesquiterpene thiocyanate from the marine sponge Acanthella cf. cavernosa and the Nudibranch Phyllidia ocellata

Abstract Three new antifungal sesquiterpenoids, cavernoisonitrile (1), cavernothiocyanate (2), and 10α-isocyano-4-amorphene (3), have been isolated from the marine sponge Acanthella cf. cavernosa, and their structures were elucidated on the basis of spectroscopic data. The nudibranch Phyllidia ocellata also contained 2 and 3.

Astrogorgiadiol and astrogorgin, inhibitors of cell division in fertilized starfish eggs, from a gorgonian astrogorgia sp.

A novel secosterol, astrogorgiadiol(1), a known diterpene ophirin(2) and a closely related diterpene, astrogorgin(3), have been isolated from a gorgonian Astrogorgia sp. as inhibitors of cell division in fertilized starfish eggs.

Two new sesquiterpene isonitriles from the nudibranch, phyllida pustulosa☆

Abstract Seven sesquiterpene isonitriles have been isolated from the nudibranch Phyllidia pustulosa, including two new compounds, one of which possesses a new tricycle skeleton. Structural determination was based mainly on NMR analyses.

Structure of a novel steroidal saponin, pachastrelloside A, obtained from a marine sponge of the genus pachastrella

Abstract A novel steroidal glycoside, pachastrelloside A, has been isolated from a marine sponge and its structure was elucidated as 2α,3β-dihydroxy-4β- O -(β-D-galactopyranosyl)-7α- O -(4- O -acetyl-β-Dxylopyranosyl)ergosta-5,24(28)-diene. This glycoside inhibits cell division of fertilized starfish eggs but does not affect nuclear divisions to form multinucleated, unicellular embryos.

Identification of 7α-hydroxy-3-oxo-4-cholestenoic acid in chronic subdural hematoma

We detected a novel kind of bile acid in the content of chronic subdural hematoma. This substance was specifically found in chronic subdural hematoma, and not in subdural hygroma, which is pathologically similar except for the lack of capsular membrane. The compound was identified as 7α-hydroxy-3-oxo-4-cholestenoic acid by high performance liquid chromatography, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectrometry. The structure was confirmed by the comparison with the chemically synthesized compound. The average contents in chronic subdural hematoma were 658.09 ± 137.53 ng/ml, while those in normal human plasma were 126.27 ± 17.73 ng/ml. It was not detected in normal cerebrospinal fluid. The higher level in chronic subdural hematoma than human plasma strongly suggests the local, extrahepatic production of this type of C 27 bile acids.

Synthetic studies on quassinoids: total synthesis of (±)-amarolide

The total synthesis of (±)-amarolide (1), a quassinoid having 10 chiral centers, was accomplished from the previously reported l2β-hydroxy-picrasan-3-one (4) by 18 step reactions.

(1R,6R,9S,10S)-9-Chloro-10-hydroxy-8-methoxycarbonyl-4-methylene-2,5-dioxabicyclo[4.4.0]Dec-3-one-7-ene, a first chlorine-containing shikimate-related metabolite from fungi

Abstract A new chlorine-containing metabolite has been isolated from two fungi, and its structure including absolute stereochemistry was established by spectroscopic and X-ray crystallographic studies.

Synthetic studies on quassinoids: a stereoselective construction of the picrasane skeleton

Abstract 12β-Hydroxypicrasan-3-one, a compound having the correct relative stereochemistry of all the six ring-juncture chiral centers of the picrasane skeleton, was synthesized from a known tricyclic compound, using the orthoester Claisen rearrangement and lead tetraacetate oxidation as key reactions.

Lumichrome Is a Putative Intrinsic Substance Inducing Larval Metamorphosis in the Ascidian Halocynthia roretzi

It has long been known that larval metamorphosis of ascidian is facilitated by exposure to adult tunic extract or larval conditioned medium. However, such a natural “inducer” has not been identified so far. Here we have succeeded in isolating an intrinsic substance inducing larval metamorphosis in the ascidian Halocynthia roretzi and identifying it as lumichrome. Lumichrome is species-specific, since it was inactive toward another ascidian (Ciona savignyi) larvae. We have also exhibited the localization of lumichrome in the larval body. Thus, we propose that lumichrome is a putative intrinsic substance inducing larval metamorphosis in H. roretzi. This is the first natural metamorphosis-inducing substance to be identified in ascidians.