Evaluation of the activity of the sponge metabolites avarol and avarone and their synthetic derivatives against fouling micro- and macroorganisms

The sesquiterpene hydroquinone avarol (1) was isolated from the marine sponge Dysidea avara, whereas the corresponding quinone, avarone (2), was obtained by oxidation of avarol, and the significantly more lipophilic compounds [3′-(p-chlorophenyl) avarone (3), 3′,4′-ethylenedithioavarone (4), 4′-isopropylthioavarone (5), 4′-tert-butylthioavarone (6), 4′-propylthioavarone (7), 4′-octylthioavarone (8)] were obtained by nucleophilic addition of thiols or p-chloroaniline to avarone. All these compounds were tested, at concentrations ranging from 0.5 to 50 μg/mL, for their effect on the settlement of the cyprid stage of Balanus amphitrite, for toxicity to both nauplii and cyprids and for their growth inhibitory activity on marine bacteria (Cobetia marina, Marinobacterium stanieri, Vibrio fischeri and Pseudoalteromonas haloplanktis) and marine fungi (Halosphaeriopsis mediosetigera, Asteromyces cruciatus, Lulworthia uniseptata and Monodictys pelagica)

A new epoxymuurolane metabolite from the soft coral Gorgonia ventalina

A novel cyclic ether, 5,10-epoxymuurolane (1), along with the sesquiterpene isosericenine (2) have been isolated, purified and identified from the organic extract of the gorgonian soft coral Gorgonia ventalina. The structure of the new natural product 1 was proposed on the basis of its spectral data, including 2D NMR experiments

Dilospiranes A and B: Diterpenes featuring novel carbocyclic units from the brown alga Dilophus spiralis

Dilospiranes A and B (1 and 2), two diterpenes featuring unprecedented carbocycles, were isolated from the organic extract of the brown alga Dilophus spiralis, collected from the coast of Elafonissos Island, Greece. The structures and the relative configurations of the isolated natural products were determined on the basis of extensive analyses of their spectroscopic data. © 2011 Elsevier Ltd. All rights reserved

Natural products with anti-HIV activity from marine organisms.

In order to combat the human immunodeficiency virus (HIV), diverse strategies have been developed to research on compounds which can be developed as therapeutic agents. Screening of natural products derived from numerous species has afforded metabolites with significant antiviral activity against the HIV. The marine environment representing approximately half of the global biodiversity offers an enormous resource for novel compounds. Currently more than 150 natural products with promising levels of anti-HIV activity have been isolated following bioassay guided protocols from aqueous or organic extracts of marine organisms. Some of the most characteristic marinemetabolites that have exhibited significant anti-HIV activity on different biochemical assays designed for chemotherapeutic strategies are: Cyanovirin-N, a protein from a blue green alga; various sulfated polysaccharides extracted from seaweeds (i.e. Nothogenia fastigiata, Aghardhiella tenera); the peptides tachyplesin and polyphemusin, which are highly abundant in hemocyte debris of the horseshoe crabs Tachypleus tridentatus and Limulus polyphemus; sponge metabolites such as avarol, avarone, ilimaquinone and several phloroglucinols; and a number of metabolites from marine fungi such as equisetin, phomasetin and integric acid. Considering that number of unique metabolites that have been isolated from a small extent of the ocean's biological and chemical diversity, the oceans represent a virtually untapped resource for the discovery of novel bioactive compounds

Volatile halogenated metabolites from marine red algae

A significant number of halogenated low molecular weight metabolites have exhibited an impressive array of biological properties ranging from antimicrobial to insecticidal activities. Studies on the natural products chemistry of the red seaweeds were recently stimulated by the discovery of the acyclic monoterpene halomon, which exhibits selective antitumor activity in the National Cancer Institute's human tumor and disease oriented in vitro screen. The present review is a taxonomy based compilation of the available literature on the halogenated volatile metabolites (C1-C10) produced by red seaweeds, with a short description of the reported ecological and pharmaceutical activities. The review begins with a presentation of simple halogenated hydrocarbons and phenols, showing their wide occurrence in rhodophyta, along with a description of simple halogenated lipids in some of the most frequently investigated red algae species and finally focuses on the chemical composition of individual red algae species. © Springer 2005

Isolation and structure elucidation of three new dolastanes from the brown alga Dilophus spiralis

Three new dolastane diterpenes (1-3) and five previously reported perhydroazulenes were isolated from the organic extracts of the brown alga Dilophus spiralis. The structure elucidation and the assignment of the relative configurations of the isolated natural products were based on extensive analyses of their spectroscopic data, whereas the absolute configuration of metabolite 2 was determined through its chemical conversion to a previously isolated compound of known configuration. © 2013 by the authors; licensee MDPI

C15 acetogenins from the red alga Laurencia obtusa

Four C15 acetogenins, 13-epilaurencienyne (3Z) (1), 13-epipinnatifidenyne (3E) (2), (3E, 6S*, 7R*, 9S*, 10S*, 12R*)-9-chloro-13 -bromo-6:12-epoxy-7, 10-diacetoxypentadec-3-en-1-yne (3), (3Z, 6S*, 7R*, 9S*, 10S*, 12R*)-9-chloro-13-bromo-6:12-epoxy-7, 10-diacetoxypentadec-3-en-1-yne (4), along with the known 13-epilaurencienyne (3E) (5), have been isolated from the organic extract of the red alga Laurencia obtusa, collected in the Aegean Sea, Greece. The structures of the new natural products, as well as their relative stereochemistry, were established by means of spectral data analysis, including 2D NMR spectroscopic experiments. Some of the new metabolites exhibited significant insecticidal activity. © 2002 Elsevier Science Ltd. All rights reserved

1,1 ‘-dimethyl-[2,2 ‘]-bipyridyldiium salt from the bivalve Callista chione

1,1’-Dimethyl-[2,2’]-bipyridyldiium salt (I) has been-isolated and identified as a new natural product from the organic extract of the marine bivalve mollusc Callista chione, order Veneridae. The structure of the new natural product I was proposed on the basis of its MS and NMR spectral data

Triperpenes from acacia mellifera (Vahl) Benth

No Abstract. IJONAS Vol. 3 (2) 2007: pp. 179-18