Tatsufumi Okino

Nostopeptins A and B were isolated from the cultured freshwater cyanobacterium Nostoc minutum (NIES-26). Their structures were elucidated on the basis of 2D NMR data and chemical degradation. These cyclic depsipeptides containing Ahp (3-amino-6-hydroxy-2-piperidone) inhibited elastase and chymotrypsin potently.

Two new diterpene formamides were isolated from the marine sponge Acanthella cavernosa collected off Yakushima Island, along with seven known diterpenes. Their structures proved to be kalihipyran derivatives on the basis of spectral data. All nine compounds showed potent antifouling activity against larvae of the barnacle Balanus amphitrite.

Natural antifouling products have been the subject of considerable attention. We screened marine algae for antifouling activity and discovered omaezallenes, the new bromoallene-containing natural products isolated from the red alga Laurencia sp. Described is the isolation, structure elucidation, and total syntheses of omaezallenes. The relative and absolute configurations of natural omaezallenes were unambiguously established through total synthesis. The antifouling activities and ecotoxicity of

Guanidine prenylation is an outstanding modification in alkaloid and peptide biosynthesis, but its enzymatic basis has remained elusive. We report the isolation of argicyclamides, a new class of cyanobactins with unique mono- and bis-prenylations on guanidine moieties, from <i>Microcystis aeruginosa</i> NIES-88. The genetic basis of argicyclamide biosynthesis was established by the heterologous expression and <i>in vitro</i> characterization of biosynthetic enzymes including AgcF, a new guanidin

Six new compounds, omaezol, intricatriol, hachijojimallenes A and B, debromoaplysinal, and 11,12-dihydro-3-hydroxyretinol have been isolated from four collections of <i>Laurencia</i> sp. These structures were determined by MS and NMR analyses. Their antifouling activities were evaluated together with eight previously known compounds isolated from the same samples. In particular, omaezol and hachijojimallene A showed potent activities (EC₅₀ = 0.15-0.23 µg/mL) against larvae of the barn

Cyanobacteria are reported as rich sources of secondary metabolites that provide biological activities such as enzyme inhibition and cytotoxicity. Ten depsipeptide derivatives (lyngbyabellins) were isolated from a Malaysian <i>Moorea bouillonii</i> and a Red Sea <i>Okeania</i> sp.: lyngbyabellins G (<b>1</b>), O (<b>2</b>), P (<b>3</b>), H (<b>4</b>), A (<b>7</b>), 27-deoxylyngbyabellin A (<b>5</b>), and homohydroxydolabellin (<b>6</b>). This study indicated that lyngbyabellins displayed cytotox

The cyanoremediation technique for heavy metal (HM) removal from wastewater using live cyanobacteria is promising to reduce the pollution risk both for the environment and human health. In this study, two widely recognized freshwater cyanobacteria, <i>Anabaena variabilis</i> and <i>Synechocystis</i> sp., were used to explore their efficacy in HM (As(v), Cd(ii), Cr(vi), Pb(ii)) removal. The different optimum adsorption conditions were pH 8 and 7.5 for <i>A. variabilis</i> and <i>Synechocystis</i>