Synthesis and biological evaluation of a focused library of beauveriolides.

Fungal beauveriolide III (1b), discovered as an inhibitor of lipid droplet accumulation in mouse macrophages and showing antiatherogenic activity in mouse model, consists of l-Phe, l-Ala, d-allo-Ile, and (3S, 4S)-3-hydroxy-4-methyloctanoic acid moieties. A combinatorial library of beauveriolide analogues focusing on l-Ala and d-allo-Ile of 1b was synthesized by combinatorial synthesis. Among them, d-Ala analogues consisting of A{2} improved their solubility, while those with 7{1,3,2},7{2,3,1}, and 7{2,3,2} were 20 times more potent than 1b.

4'''-N-demethylspiramycin derivatives: synthesis and evaluation of effectiveness against drug-resistant bacteria.

18-amino-4''-O-benzoyl-4'''-N-demethyl-18-deoxospiramycins were designed and synthesized. Synthetic strategy involved selective demethylation of the dimethylamino group in forosamine, benzoylation of the hydroxyl group at the C4'' position and reductive N-amination of the formyl group. Antibacterial characteristics of spiramycin derivatives were tested.

Efficient total synthesis of novel bioactive microbial metabolites.

Bioactive natural products produced by microbes have almost limitless potential in pharmaceutical applications, and the organic synthesis of such products as lead compounds will result in the creation of new and widely useful pharmaceutical products. A program of discovery of naturally occurring bioactive microbial metabolites has been ongoing at the Kitasato Institute. We have also developed efficient, rational, and highly flexible production methods for generation of target compounds, synthesis of related compounds, elucidation of their structure-activity relationships, and the possible creation of improved bioactive compounds.

Fungerin, a fungal alkaloid, arrests the cell cycle in M phase by inhibition of microtubule polymerization.

A fungal alkaloid fungerin was found to arrest the cell cycle of Jurkat cells at the G2/M phase, then to induce apoptosis. Immunoblotting showed that fungerin led to hyperphosphorylation for Cdc25C and dephosphorylation of Cdc2, indicating that the compound arrests the cell cycle at the M phase. Moreover, fungerin inhibited the polymerization of microtubule proteins in vitro.

Oxaline, a fungal alkaloid, arrests the cell cycle in M phase by inhibition of tubulin polymerization.

Oxaline and neoxaline, fungal alkaloids, were found to inhibit cell proliferation and to induce cell cycle arrest at the G(2)/M phase in Jurkat cells. CBP501 (a peptide corresponding to amino acids 211-221 of Cdc25C phosphatase), which inhibits the G(2) checkpoint, did not affect the G(2)/M arrest caused by oxaline, suggesting that oxaline causes M phase arrest but not G(2) phase arrest. The Cdc2 phosphorylation level of oxaline-treated cell lysate was lower than that of the control cells, indicating that oxaline arrests the M phase.

Synthesis and biological evaluation of novel 4"-alkoxy avermectin derivatives.

Novel 4"-alkoxy avermectin derivatives were synthesized via rhodium carbenoid mediated O-H insertion reaction and tested for antiparasite activity against Artemia salina and Caenorhabditis elegans.

Synthesis and biological activities of novel 4"-alkylidene avermectin derivatives.

Horner-Emmons reaction of 4"-dehydro-5-O-TBDMS-avermectin B(1a) with a variety of phosphorus ylides using LHMDS gave novel 4"-alkylidene avermectin derivatives in high yields. Further modifications led to derivatives bearing diverse functional groups. The new avermectin derivatives showed potent growth inhibitory activity against Artemia salina and Caenorhabditis elegans.

Takanawaenes, novel antifungal antibiotics produced by Streptomyces sp. K99-5278. II. Structure elucidation.

The structures of takanawaenes A, B and C, novel antifungal antibiotics produced by Streptomyces sp. K99-5278, were elucidated by various spectroscopic analyses including UV and NMR, and spectrometric analyses including MS. They have the common skeleton of a 28-membered pentaene macrolide.

Takanawaenes, novel antifungal antibiotics produced by Streptomyces sp. K99-5278. I. Taxonomy, fermentation, isolation and biological properties.

Three new pentaene macrolides having a 28-membered ring, designated takanawaenes A, B and C, were isolated from the fermentation broth of Streptomyces sp. K99-5278 by solvent extraction, silica-gel column chromatography and HPLC. Takanawaenes showed antifungal activity against Aspergillus niger, Mucor racemosus, Candida albicans and Saccharomyces cerevisiae.

Chlorogentisylquinone, a new neutral sphingomyelinase inhibitor, produced by a marine fungus.

Chlorogentisylquinone, a new inhibitor of neutral sphingomyelinase activity, was purified from the culture broth of a fungal strain FOM-8108 isolated from a marine environment by solvent extraction, silica gel chromatography and Sephadex LH-20 chromatography. Its chemical structure was elucidated by spectroscopic studies including 1H, 13C, DEPT, HMQC and HMBC NMR experiments. Chlorogentisylquinone inhibited neutral sphingomyelinase activity of rat brain membranes with an IC50 value of 1.