Makoto Iwashima

Three new chlorinated marine steroids, yonarasterols G, H and I, isolated from the Okinawan soft coral, Clavularia viridis

Three new chlorinated marine steroids, yonarasterols G, H and I, were isolated from the Okinawan soft coral, Clavularia viridis. Their structures including the absolute configuration were determined based on the results of spectroscopic analysis and chemical conversion.

New marine steroids, yonarasterols, isolated from the okinawan soft coral, Clavularia viridis.

Six new marine steroids, yonarasterols A through F, were isolated from the Okinawan soft coral, Clavularia viridis. Their structures were determined based on the results of spectroscopic analysis.

Clavirins, a new type of marine oxylipins with growth-inhibitory activity from the Okinawan soft coral, Clavularia viridis

Two new marine carbocyclic oxylipins, clavirin I (1) and II (2), were isolated from the Okinawan soft coral, Clavularia viridis. Their structures containing unique α-side chains were determined, based on spectroscopic analysis and stereoselective total synthesis. Clavirins showed growth-inhibitory activity toward HeLa S3 cells.

Baicalein 5,6,7-trimethyl ether, a flavonoid derivative, stimulates fatty acid β-oxidation in skin fibroblasts of X-linked adrenoleukodystrophy

The purpose of the present study is to identify bioactive compounds with potential for X‐linked adrenoleukodystrophy (X‐ALD) pharmacological therapy. Various plant natural products including flavonoids were tested for their ability to ameliorate the abnormality of very long chain fatty acid (VLCFA) metabolism in cultured skin‐fibroblasts from X‐ALD patients. Of the compounds tested, baicalein 5,6,7‐trimethyl ether (baicalein‐tri‐Me) was found to significantly stimulate the VLCFA β‐oxidation activity. Furthermore, the incorporation of [1‐14C]lignoceric acid into cholesteryl esters was markedly reduced towards the normal level and the VLCFA (C24:0 and C26:0) content was decreased. These results make baicalein‐tri‐Me a candidate for the therapeutic compound for X‐ALD.

New bioactive marine steroids from the Okinawan soft coral Clavularia viridis

Eight new marine steroids were isolated from the Okinawan soft coral Clavularia viridis Quoy and Gaimard. Their structures were determined based on spectroscopic analysis, chemical conversion, and X-ray crystallographic analysis. Steroids 5 and 6 showed growth inhibition activity toward HeLa S3 cells and human diploid cells in vitro.

New marine prostanoids, preclavulone lactones, from the Okinawan soft coral Clavularia viridis

Abstract Two new marine prostanoids, preclavulone lactones I (1) and II (2) were isolated from the Okinawan soft coral, Clavularia viridis . Their structures were determined based on spectroscopic analysis and chemical synthesis from ( S )-malic acid. Preclavulone lactones with side chains having absolute configurations opposite to those of mammalian prostanoids could be recognized as key intermediates in biosynthesis of clavulones.

Determination of absolute configurations of β- or γ-methyl substituted secondary alcohols by NMR spectroscopy

Abstract A new method has been developed for determining the absolute configurations of acyclic β- or γ-methyl substituted secondary alcohols using their 2NMA esters. The 1 H-NMR spectra of ( R )- and ( S )-2NMA esters of model compounds were measured, and Δδ values (δ R-ester - δ S-ester ) for the corresponding protons were compared between syn and anti compounds. Threshold values important for judging the relative stereochemistry of the two chiral centers bearing methyl and hydroxy groups were obtained. The absolute configuration of the chiral center bearing a secondary hydroxy group is easily determined based on the sign of Δδ values as in the MTPA method and thus in the present study it was also possible to clearly determine the absolute configuration of the chiral center bearing a methyl group.