Nobuhiro Fusetani

Calyculin A and okadaic acid: Inhibitors of protein phosphatase activity

Calyculin A and okadaic acid induce contraction in smooth muscle fibers. Okadaic acid is an inhibitor of phosphatase activity and the aims of this study were to determine if calyculin A also inhibits phosphatase and to screen effects of both compounds on various phosphatases. Neither compound inhibited acid or alkaline phosphatases, nor the phosphotyrosine protein phosphatase. Both compounds were potent inhibitors of the catalytic subunit of type-2A phosphatase, with IC50 values of 0.5 to 1 nM. With the catalytic subunit of protein phosphatase type-1, calyculin A was a more effective inhibitor than okadaic acid, IC50 values for calyculin A were about 2 nM and for okadaic acid between 60 and 500 nM. The endogenous phosphatase of smooth muscle myosin B was inhibited by both compounds with IC50 values of 0.3 to 0.7 nM and 15 to 70 nM, for calyculin A and okadaic acid, respectively. The partially purified catalytic subunit from myosin B had IC50 values of 0.7 and 200 nM for calyculin A and okadaic acid, respectively. The pattern of inhibition for the phosphatase in myosin B therefore is similar to that of the type-1 enzyme.

Biofouling and antifouling

Most benthic organisms produce planktonic larvae in their life cycles; larval settlement and metamorphosis are influenced by many environmental factors, especially chemical cues originating from conspecific adults, prey organisms, and substrates. On the other hand, larval settlement of other species endangers the survival of benthic organisms which therefore have antifouling defense. Marine natural products involved in biofouling and antifouling are described.

Marine pharmacology in 2007–8: Marine compounds with antibacterial, anticoagulant, antifungal, anti-inflammatory, antimalarial, antiprotozoal, antituberculosis, and antiviral activities; affecting the immune and nervous system, and other miscellaneous mechanisms of action

Abstract The peer-reviewed marine pharmacology literature in 2007–8 is covered in this review, which follows a similar format to the previous 1998–2006 reviews of this series. The preclinical pharmacology of structurally characterized marine compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, anticoagulant, antifungal, antimalarial, antiprotozoal, antituberculosis and antiviral activities were reported for 74 marine natural products. Additionally, 59 marine compounds were reported to affect the cardiovascular, immune and nervous systems as well as to possess anti-inflammatory effects. Finally, 65 marine metabolites were shown to bind to a variety of receptors and miscellaneous molecular targets, and thus upon further completion of mechanism of action studies, will contribute to several pharmacological classes. Marine pharmacology research during 2007–8 remained a global enterprise, with researchers from 26 countries, and the United States, contributing to the preclinical pharmacology of 197 marine compounds which are part of the preclinical marine pharmaceuticals pipeline. Sustained preclinical research with marine natural products demonstrating novel pharmacological activities, will probably result in the expansion of the current marine pharmaceutical clinical pipeline, which currently consists of 13 marine natural products, analogs or derivatives targeting a limited number of disease categories.

Marine Pharmacology in 2009-2011: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis, and Antiviral Activities; Affecting the Immune and Nervous Systems, and other Miscellaneous Mechanisms of Action †

The peer-reviewed marine pharmacology literature from 2009 to 2011 is presented in this review, following the format used in the 1998–2008 reviews of this series. The pharmacology of structurally-characterized compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral pharmacological activities were reported for 102 marine natural products. Additionally, 60 marine compounds were observed to affect the immune and nervous system as well as possess antidiabetic and anti-inflammatory effects. Finally, 68 marine metabolites were shown to interact with a variety of receptors and molecular targets, and thus will probably contribute to multiple pharmacological classes upon further mechanism of action studies. Marine pharmacology during 2009–2011 remained a global enterprise, with researchers from 35 countries, and the United States, contributing to the preclinical pharmacology of 262 marine compounds which are part of the preclinical pharmaceutical pipeline. Continued pharmacological research with marine natural products will contribute to enhance the marine pharmaceutical clinical pipeline, which in 2013 consisted of 17 marine natural products, analogs or derivatives targeting a limited number of disease categories.

l-Kynurenine, an amino acid identified as a sex pheromone in the urine of ovulated female masu salmon

Many animals employ sex pheromones to find mating partners during their reproductive seasons. However, most sex pheromones of vertebrates remain to be identified. Over the past 20 years, steroids and prostaglandins have been identified as sex pheromones in several fishes. These pheromones are broadly termed “hormonal pheromones” because they or their precursors act as hormones in these fishes. Hitherto, no other type of sex pheromone has been unambiguously identified in teleost fish. Here we report the identification of a “nonhormonal pheromone” in teleost fish. The urine of the reproductively mature female masu salmon (Oncorhynchus masou) contains a male-attracting pheromone. Bioassay-guided fractionation yielded an active compound that was identical to l-kynurenine in spectral and chromatographic properties. l-Kynurenine is a major metabolite of l-tryptophan in vertebrates. This pheromone elicits a male-specific behavior at even picomolar concentrations; its electrophysiological threshold is 10−14 M. l-Kynurenine is a reasonable substance for female masu salmon to advertise their readiness for mating.

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.

Mycalolides A – C, hybrid macrolides of ulapualides and halichondramide, from a sponge of the genus Mycale

Three cytotoxic macrolides, mycalolides A – C have been isolated from a sponge Mycale sp., and their structures elucidated to be hybrids of ulapualides and halichondramide mainly by analyses of 2D NMR spectra as well as by comparison of spectral data.

Terpenoids with antifouling activity against barnacle larvae from the marine sponge Acanthella cavernosa

Abstract Fourteen terpenoids, including six new compounds, have been isolated from the marine sponge Acanthella cavernosa collected off Hachijo-jima Island. They inhibit of larval attachment and metamorphosis of the barnacle Balanus amphitrite. Their structures were determined mainly by spectroscopic methods.

Purification of a larval settlement-inducing protein complex (SIPC) of the barnacle, Balanus amphitrite

Many species of barnacles live gregariously, and chemical cues from conspecifics are believed to induce settlement of cypris larvae. Settlement-inducing factors from the adult barnacle Balanus amphitrite have been partially purified using a nitrocellulose membrane-based assay. The assay was designed for research on active proteins adsorbed to substrata. A settlement-inducing protein complex (SIPC) with a high molecular weight was purified from whole adult barnacles by ammonium sulphate precipitation, ion exchange chromatography on Mono Q, gel filtration on Superdex 200 HR, and lectin affinity chromatography on LCA-Sepharose. SDS-polyacrylamide gel electrophoresis of the purified protein complex showed three major protein bands of 76, 88, and 98 kDa and one minor band of 32 kDa under reducing conditions. Lentil lectin (LCA), a lectin that inhibits adult extract-induced settlement, was found to bind to the subunits of 76, 88, and 98 kDa by lectin blotting. Moreover, we isolated three LCA-binding subunits of SIPC by SDS-PAGE and found that each individual subunit also induced larval settlement. It would appear, therefore, that a specific sugar chain of SIPC plays an important role in the settlement of B. amphitrite. J. Exp. Zool. 281:12–20, 1998.

Cyclostellettamines A-F, pyridine alkaloids which inhibit binding of methyl quinuclidinyl benzilate (QNB) to muscarinic acetylcholine receptors, from the marine sponge, Stelletta maxima

Abstract Six new pyridine alkaloids, cyclostellettamines A-F were isolated as muscarinic receptor binding inhibitors from the marine sponge Stelletta maxima , and their structures were elucidated on the basis of spectroscopic data.