Klaus D. Feussner

Naseseazines A and B: A New Dimeric Diketopiperazine Framework from a Marine-Derived Actinomycete, Streptomyces sp.

Chemical analysis of a Streptomyces sp. (CMB-MQ030) isolated from a Fijian marine sediment yielded two new diketopiperazines, naseseazines A and B (1, 2), featuring a new dimeric framework. Structures were determined by detailed spectroscopic analysis and C(3) Marfeys analysis.

The inhibition of TNF-α-induced NF-κB activation by marine natural products

The deregulated activation of NF-kappaB is associated with cancer development and inflammatory diseases. With an aim to find new NF-kappaB inhibitors, we purified and characterized compounds from extracts of the Fijian sponge Rhabdastrella globostellata, the crinoid Comanthus parvicirrus, the soft corals Sarcophyton sp. nov. and Sinularia sp., and the gorgonian Subergorgia sp. after an initial screening of 266 extracts from different marine origins. Results obtained show that selected purified compounds had a cytotoxic effect on the human leukaemia cell line K562, inhibited both TNF-alpha-induced NF-kappaB-DNA binding as well as TNF-alpha-induced IkappaBalpha degradation and nuclear translocation of p50/p65. Furthermore, we observed the inhibition of NF-kappaB activation induced by an overexpression of IKKbeta. Interestingly, natural products inhibited IKKbeta kinase as well as the 26S proteasome proteolytic activity.

Aurantoside K, a New Antifungal Tetramic Acid Glycoside from a Fijian Marine Sponge of the Genus Melophlus

A new tetramic acid glycoside, aurantoside K, was isolated from a marine sponge belonging to the genus Melophlus. The structure of the compound was elucidated on the basis of spectroscopic analysis (1H NMR, 1H–1H COSY, HSQC, and HMBC, as well as high-resolution ESILCMS). Aurantoside K did not show any significant activity in antimalarial, antibacterial, or HCT-116 cytotoxicity assays, but exhibited a wide spectrum of antifungal activity against wild type Candida albicans, amphotericin-resistant C. albicans, Cryptococcus neoformans, Aspergillus niger, Penicillium sp., Rhizopus sporangia and Sordaria sp.

Evaluation of the Antioxidant Activity of the Marine Pyrroloiminoquinone Makaluvamines

Makaluvamines are pyrroloiminoquinones isolated from Zyzzya sponges. Until now, they have been described as topoisomerase II inhibitors with cytotoxic effects in diverse tumor cell lines. In the present work, seven makaluvamines were tested in several antioxidant assays in primary cortical neurons and neuroblastoma cells. Among the alkaloids studied, makaluvamine J was the most active in all the assays. This compound was able to reduce the mitochondrial damage elicited by the well-known stressor H2O2. The antioxidant properties of makaluvamine J are related to an improvement of the endogenous antioxidant defenses of glutathione and catalase. SHSY5Y assays proved that this compound acts as a Nrf2 activator leading to an improvement of antioxidant defenses. A low concentration of 10 nM is able to reduce the reactive oxygen species release and maintain a correct mitochondrial function. Based on these results, non-substituted nitrogen in the pyrrole plus the presence of a p-hydroxystyryl without a double bond seems to be the most active structure with a complete antioxidant effect in neuronal cells.

Ostreobium quekettii (Ostreobiaceae: Chlorophyceae) invading the barnacle Acasta sp. (Pendunculata: Acastinae), endozoic in the octocoral rumphella suffruticosa (Alcyonacea: Gorgoniidae) from Fiji, south pacific

Abstract The eukaryotic alga Ostreobium quekettii (Ostreobiaceae: Chlorophyceae) is reported from Fiji for the first time. It is found creeping over the calcareous plates of dead specimens of species of a barnacle genus Acasta (Pendunculata: Acastinae), which was endozoic in the gorgonian Rumphella suffruticosa. The barnacles are lodged in cavities in the coenenchyme of the gorgonian, mostly in the vicinity of colonial branching points. There is little external evidence of the location of the barnacles where the gorgonian tissue is thick, but where it is thin, prominent galls are visible. There is no evidence that the barnacle or algal association causes stress to the host, which was otherwise healthy in appearance. The presence of the algae would appear to be associated with the occurrence of the barnacles.

Marinocyanins, cytotoxic bromo-phenazinone meroterpenoids from a marine bacterium from the streptomycete clade MAR4

Six cytotoxic and antimicrobial metabolites of a new bromo-phenazinone class, the marinocyanins A-F (1-6), were isolated together with the known bacterial metabolites 2-bromo-1-hydroxyphenazine (7), lavanducyanin (8, WS-9659A) and its chlorinated analog WS-9659B (9). These metabolites were purified by bioassay-guided fractionation of the extracts of our MAR4 marine actinomycete strains CNS-284 and CNY-960. The structures of the new compounds were determined by detailed spectroscopic methods and marinocyanin A (1) was confirmed by crystallographic methods. The marinocyanins represent the first bromo-phenazinones with an N-isoprenoid substituent in the skeleton. Marinocyanins A-F show strong to weak cytotoxicity against HCT-116 human colon carcinoma and possess modest antimicrobial activities against Staphylococcus aureus and amphotericin-resistant Candida albicans.

Five new species of Sarcophyton (Coelenterata: Octocorallia) from the Fiji Islands

This paper describes five new species of the soft coral genus Sarcophyton which were identified by their morphological characters (colony form and sclerite shape). The five species have been named: S. aalbersbergi sp. nov., S. aldersladei sp. nov., S. alexanderi sp. nov., S. skeltoni sp. nov and S. soapiae sp. nov. For the first time it is documented that there is a Sarcophyton species that does not have sclerites in the interior of the disc.

Antimicrobial and cytotoxic activities of marine plants and invertebrates from the coast of Espirito Santo in Vanuatu

Marine invertebrates and algae collected off the coast of Espirito Santo in Vanuatu were investigated for antimicrobial and cytotoxic activities. The combined crude methanol-dichloromethane extracts from 52 sponges, 5 algae, 17 soft corals (cnidaria) and 5 other samples of various marine invertebrates were screened for cytotoxicity, antibacterial and antifungal properties. The cytotoxicity of the samples was determined using a brine shrimp lethality test and, notably, 78% of the invertebrate and algae samples showed cytotoxic activity against brine shrimps with the sponge Crella spinulata displaying the strongest activity. Antimicrobial activity was determined against three resistant bacterial strains and two fungal strains. A total of 42% of the samples tested showed antimicrobial activity against at least one of the five strains. The most potent antibacterial activities were recorded for the sponges Lamellodysidea herbacea, Phyllospongia sp., a sponge in the order Halichondrida and Hippospongia metachromia. A Theonella sp. sponge displayed the strongest antifungal activity.