Isolation and identification of a potent antimalarial and antibacterial polyacetylene from Bidens pilosa.

Diseases caused by malaria parasites and pathogenic bacteria were thought to be on the brink of eradication in the 1950-1960s, but they have once again become a serious threat to mankind as a result of the appearance of multidrug resistant strains. The spread of these multidrug resistant organisms has prompted a worldwide search for new classes of effective antimalarial and antibacterial drugs. Natural products have been recognized as highly important candidates for this purpose. Our attention has focused on the herbal plant Bidens pilosa, a weed common throughout the world, as one of the target plants in the search for new active compounds, owing to its empirical use in the treatment of infectious diseases and to pharmaco-chemical studies of its crude extract. We report the isolation of two new compounds of B. pilosa, the linear polyacetylenic diol 1 and its glucoside 2 which have previously been isolated from different plants. Compound 1 exhibited highly potent antimalarial and antibacterial properties in vitro as well as potent antimalarial activity by way of intravenous injection in vivo, thereby representing a promising new class of drugs potentially effective in the treatment of malarial and bacterial diseases. We suspect that discovery of these compounds in B. pilosa in appreciable quantity is because the Fijian tradition of using the fresh plant for extraction rather than the Asian tradition of using dried plants (1 is unstable in the dried state) was followed.

Nine acetylenic alcohols isolated from the Okinawan marine sponge of the genus Petrosia (Strongylophora).

Nine new acetylenic alcohols 1-9 were isolated from a marine sponge belonging to the genus Petrosia (Strongylophora). The structures were elucidated mainly based on the analysis of one-and two-dimensional NMR spectral data. To determine the position of the central double bonds in 1-8, each compound was cleaved with OsO(4) and HIO(4), and the resulting aldehyde was converted to the corresponding 2,4-dinitrophenylhydrazone. Analysis of the high-resolution mass and (13)C NMR spectral data of each 2,4-dinitrophenylhydrazone clarified the position of the central double bonds in 1-8.

Total synthesis of (+/-)-clavubicyclone.

[reaction: see text] The total synthesis of racemic clavubicyclone (1), which was isolated from Okinawan soft coral by our group, is described. The bicyclo[3.2.1]octane skeleton was prepared by Cope rearrangement of a divinylcyclopropane derivative. Three functional groups on the skeleton were constructed by Barton decarboxylation, Wittig reaction, and alkylation.

Efficient solid-phase synthesis of clavulones via sequential coupling of alpha- and omega-chains.

We describe an efficient solid-phase synthesis of clavulones via the sequential coupling of the alpha- and omega-chains, involving two separate carbon-carbon bond-forming steps. The tetrahydropyranyl linker survived these reaction conditions and was cleaved without decomposing the unstable cross-conjugated dienones. Our methodology has allowed us to prepare six clavulone derivatives that are varied within the alpha-chain.

Molecular phylogenetic relationships between prostanoid-containing Okinawan soft coral ( Clavularia viridis) and nonprostanoid-containing Clavularia species based on ribosomal ITS sequence.

To study phylogenetic relationships among Okinawan soft corals of the genus Clavularia, the ribosomal internal transcribed spacer sequences of host corals and the 18S rDNA sequences of symbiotic algae were analyzed. The molecular phylogenetic trees of hosts showed that a prostanoid-containing species, Clavularia viridis, is deeply diverged from other species of Clavularia which do not biosynthesize the prostanoids as the main secondary metabolites. Comparison of their trees suggested poor phylogenetic concordance between hosts and symbionts.

Localization of clavulones, prostanoids with antitumor activity, within the Okinawan soft coral Clavularia viridis (Alcyonacea, Clavulariidae): preparation of a high-purity Symbiodinium fraction using a protease and a detergent.

To investigate the localization of clavulones (CV), prostanoids with antitumor activity, in the Okinawan soft coral Clavularia viridis, we developed a method for the isolation of Symbiodinium cells from the coral, i.e., treatment of a coral homogenate with a protease, pronase E, and a detergent, Nonidet P-40. The conditions for the treatment were optimized by monitoring the morphology microscopically and the amount of chlorophyll in the Symbiodinium fraction (SymF) optically. To evaluate the purity of SymF and a Symbiodinium-free coral fraction (CorF), we analyzed them for proteins and lipids using cultivated Symbiodinium as a reference. TLC of lipids revealed that SymF contained a greater amount of glycolipids, whereas CorF comprised mostly phospholipids. SDS-PAGE of proteins in SymF and CorF revealed their distinct profiles. Thus, we could obtain each fraction with high purity; we reached the conclusion that CV and arachidonic acid, their possible precursor, are localized exclusively in the insoluble fraction of host coral cells.

Toward the synthesis of didemnaketal B: a convergent synthesis of the C9-C28 subunit.

Synthesis of the C9-C28 subunit of didemnaketal B has been developed. This subunit was convergently prepared from four chiral synthons and at the longest linear sequence required 16 steps.

Structure of an unsaturated fatty acid with unique vicinal dimethyl branches isolated from the Okinawan soft coral of the genus Sinularia.

A new unsaturated fatty acid with unique vicinal dimethyl branches was isolated from the Okinawan soft coral of the genus Sinularia. The structure of the compound was determined based on the results of spectroscopic analysis and chemical conversion. The absolute configuration was deduced by applying the Ohrui-Akasaka method.

Brianodins A-D, briarane-type diterpenoids from soft coral Pachyclavularia sp.

Four new briarane-type diterpenoids, brianodins A-D ( 1- 4), were isolated from a soft coral, Pachyclavularia sp., and the structures and relative stereochemistry of 1- 4 were elucidated on the basis of spectroscopic data. The absolute configurations of 3 and 4 were assigned by the MTPA method. Brianodin A ( 1) showed a modest cytotoxicity.

Marine diterpenoids with a briarane skeleton from the Okinawan soft coral Pachyclavularia violacea.

Five new briarane-type diterpenoids, pachyclavulides E (5), F (6), G (7), H (8) and I (9), were isolated from the Okinawan soft coral Pachyclavularia violacea. The structures of these compounds were elucidated based on the results of spectroscopic analysis. Compound 5 showed a weak growth-inhibitory activity in vitro toward cancer cells.

Structure of cymbidine A, a monomeric peptidoglycan-related compound with hypotensive and diuretic activities, isolated from a higher plant, Cymbidium goeringii (Orchidaceae).

The structure of a new monomeric peptidoglycan-related compound with hypotensive and diuretic activities, cymbidine A (1) isolated from the orchid Cymbidium goeringii, was elucidated mainly by spectroscopic analysis. The structure of 1 was shown to involve four amino acids (D-alanin, meso-diaminopimelic acid, D-gultamic acid, and L-valine) and two amino sugars (N-acetylglucosamine and 1,6-anhydro-N-acetylmuramic acid). The sequence of the amino acids and amino sugars was determined by the analysis of 2D NMR data. The absolute stereochemistries of the three amino acids (D-Ala, D-Glu and L-Val) were determined by the modified Marfey's method, and the (6S,10R) configurations of meso-diaminopimelic acid in 1 were indicated on the basis of the CD analysis. The absolute stereochemistry of 1,6-anhydro-N-acetylmuramic acid was also determined by CD data.

Briarane-type diterpenoids from the Okinawan soft coral Pachyclavularia violacea.

Four new briarane-type diterpenoids, pachyclavulides A (1), B (2), C (3), and D (4), were isolated from the Okinawan soft coral Pachyclavularia violacea. The structures of these compounds were elucidated on the basis of the results of spectroscopic analysis. The absolute configuration of pachyclavulide A (1) was determined by the X-ray crystallographic analysis of its p-bromobenzoyl ester.

Solid-phase synthesis and biological activity of a combinatorial cross-conjugated dienone library.

The solid-phase synthesis of a combinatorial cross-conjugated dienone library based on the structure of clavulones and their biological activity are reported. Clavulones are a family of marine prostanoids, and are composed of a cross-conjugated dienone system bearing two alkyl side-chains. The cross-conjugated dienone system irreversibly reacted with two nucleophiles. Our strategy for the solid-phase synthesis of the cross-conjugated dienones involves the Sonogashira-coupling reaction of a solid-supported cyclopentenone 10 bearing an acetylene group, followed by aldol condensation with aldehydes. The diphenyl derivative 7 aA was prepared from the solid-supported cyclopentenone 10 in 56% total yield. Combinatorial synthesis of a small library using twelve halides and eight aldehydes resulted in the production of 74 desired compounds from 98 candidates, and were detected by their mass spectra. Antiproliferative effects of the crude compounds against HeLaS3 cells showed that eleven samples showed strong antitumor activity (IC50<0.05 microM). Further biological examination of four purified compounds by using five tumor cell lines (A549, HeLaS3, MCF7, TMF1, and P388) revealed strong cytotoxicity comparable to that of adriamycin.

Acetylenic strongylodiols from a Petrosia (Strongylophora) Okinawan marine sponge.

Seven new long-chain acetylenic alcohols, strongylodiols D-J, were isolated from an Okinawan marine sponge of the genus Petrosia (Strongylophora). The structures of these compounds were elucidated on the basis of the results of spectroscopic analysis and chemical reaction. Analysis of the MNA esters of the acetylenic alcohols disclosed that these compounds were each an enantiomeric mixture in a different ratio.

Isolation and structures of new halogenated prostanoids from the Okinawan soft coral Clavularia viridis.

Fifteen new halogenated prostanoids 9-23 were isolated as minor constituents from the Okinawan soft coral Clavularia viridis. Compounds 9-11 were new members of iodovulone, and compounds 12-18 were 12-O-acetyliodovulones, 12-O-acetylbromovulones, and 12-O-acetylchlorovulones. Compounds 19-23 were 10,11-epoxy congeners of iodovulone, bromovulone, and chlorovulone. The structures of these compounds were determined on the basis of spectroscopic analysis and chemical conversion.

Isolation of three marine prostanoids, possible biosynthetic intermediates for clavulones, from the Okinawan soft coral Clavularia viridis.

Three marine prostanoids, 1, 2, and 3, were isolated from the extract of the Okinawan soft coral Clavularia viridis. The structures of these compounds were assigned based on the results of spectroscopic analysis. Compound 1 was shown to be preclavulone-A methyl ester, and this is the first isolation of the ester of preclavulone-A as a natural product. Preclavulone-A is proposed to be the key intermediate in the biosynthesis of marine prostanoids exemplified by clavulones in C. viridis. The new prostanoid 3 was suggested to be a biosynthetic intermediate from preclavulone-A to clavulones, and a possible biogenetic pathway via 3 is proposed.

Tricycloclavulone and clavubicyclone, novel prostanoid-related marine oxylipins, isolated from the Okinawan soft coral Clavularia viridis.

Two novel prostanoid-related marine oxylipins, tricycloclavulone (1) and clavubicyclone (2), were isolated from the Okinawan soft coral Clavularia viridis. The structures of 1, having a tricyclo[5.3.0.0(1,4)]decane ring system, and 2, having a bicyclo[3.2.1]octane ring system, were elucidated on the basis of spectroscopic analysis. Clavubicyclone showed a moderate growth inhibition activity against tumor cells in vitro.

New biologically active marine sesquiterpenoid and steroid from the okinawan sponge of the genus Axinyssa.

A new bisabolane-type sesquiterpenoid, (E)-3-isocyanobisabolane-7,10-diene (1), and a new epidioxyergostane-type steroid, 9(11)-dehydroaxinysterol (2), were isolated from the Okinawan sponge of the genus Axinyssa. Their structures were elucidated based on the results of spectroscopic analysis and chemical conversion. Epidioxysterol 2 was found to show significant growth inhibitory effects against human cancer cell lines.

New marine sesquiterpenoids and diterpenoids from the Okinawan soft coral Clavularia koellikeri.

Six new terpenoids (two maaliane-type sesquiterpenoids, 1 and 2, one aromadendrane-type sesquiterpenoid, 3, one noraromadendrane-type sesquiterpenoid, 4, and two neodolabellane-type diterpenoids, 5 and 6) were isolated from the Okinawan soft coral Clavularia koellikeri. The structures of these compounds were determined on the basis of the results of spectroscopic analysis, chemical conversion, and X-ray crystallographic analysis. Compound 6 exhibited modest growth-inhibition effect in vitro toward tumor cells.

Stolonilactone, a novel terpenoid-related compound, isolated from the Okinawan soft coral Clavularia koellikeri.

A novel terpenoid-related compound, stolonilactone (1), was isolated from the Okinawan soft coral Clavularia koellikeri. The structure of 1 was elucidated on the basis of spectroscopic analysis. A possible biogenesis of 1 through the [4 + 2]-cycloaddition of a trisnorsesquiterpenoid-type diene and a cembranolide-type dienophile is proposed.