Cytotoxic Compounds of Two Demosponges (Aplysina aerophoba and Spongia sp.) from the Aegean Sea

The class of demosponges is the biggest and most diverse of all described sponge species and it is reported to produce a plethora of chemically different metabolites with interesting biological activities. The focus of the present study was to investigate the chemical composition of two Mediterranean demosponges, targeting their brominated compounds and prenylated hydroquinones, compounds with interesting cytotoxic and anti-microbial properties. In order to gain a deeper insight into the chemical diversity of their metabolites and their activities, 20 pure secondary metabolites including new natural products were isolated from two different species (Aplysina aerophoba and Spongia sp.) using various chromatographic techniques. Their structures were confirmed by NMR and HRMS, revealing molecules with various chemical scaffolds, mainly prenylated hydroquinones from Spongia sp. and halogenated compounds from Aplysina aerophoba, including 5 novel natural products. The isolated compounds were investigated for their cytotoxic properties using 9 different cell lines, and especially one compound, 2,6-dibromo-4-hydroxy-4-methoxycarbonylmethylcyclohexa-2,5-dien-1-one showed good activities in all tested models.

Grazing results in mobilization of spherulous cells and re-allocation of secondary metabolites to the surface in the sponge Aplysina aerophoba

On the sea floor, prey and predator commonly engage in a chemical warfare. Here, sponges thrive due to their specific and diverse chemical arsenal. Yet, some animals use these chemically-defended organisms as food and home. Most research on sponge chemical ecology has characterized crude extracts and investigated defences against generalist predators like fish. Consequently, we know little about intraindividual chemical dynamics and responses to specialist grazers. Here, we studied the response of the sponge Aplysina aerophoba to grazing by the opistobranch Tylodina perversa, in comparison to mechanical damage, at the cellular (via microscopy) and chemical level (via matrix-assisted laser desorption/ionization imaging mass spectrometry). We characterized the distribution of two major brominated compounds in A. aerophoba, aerophobin-2 and aeroplysinin-1, and identified a generalized wounding response that was similar in both wounding treatments: (i) brominated compound-carrying cells (spherulous cells) accumulated at the wound and (ii) secondary metabolites reallocated to the sponge surface. Upon mechanical damage, the wound turned dark due to oxidized compounds, causing T. perversa deterrence. During grazing, T. perversa’s way of feeding prevented oxidation. Thus, the sponge has not evolved a specific response to this specialist predator, but rather relies on rapid regeneration and flexible allocation of constitutive defences.

Monomeric and Dimeric Bromophenols from the Red Alga Ceramium Sp. with Antioxidant and Anti-Inflammatory Activities

<p>LC-MS²-based molecular networking using the Global Natural Products Social (GNPS) tool revealed a rich assortment of brominated compounds present in the antioxidant fraction of a red algal extract (<i>Ceramium</i> sp.) Further chemical investigation led to discovery of one monomeric bromophenol (lanosol isopropyl ether, <b>1</b>) and seven dimeric ones (bromourceolatols A-G, <b>2</b>-<b>8</b>), all of which are previously undescribed. Their structures were elucidated by extensive analysis of their spectroscopic data. Compounds <b>2</b>-<b>8 </b>were determined to be racemic trans-type isomers by NOESY, specific optical rotation, and ECD. Compounds <b>1</b> and <b>3</b> displayed antioxidant activity with their EC₅₀ of 44.4 and 47.0 μM, respectively, for scavenging DPPH free radicals while compounds <b>2</b> and <b>4</b> had approximate EC₅₀ values of ~ 64 μM. Furthermore, compounds <b>2</b>, <b>3</b>, and <b>7</b> exhibited relatively potent anti-inflammatory activity at 32 μM by quenching 97%, 47%, and 73% of nitric oxide induced by bacterial lipopolysaccharide in macrophage RAW264.7 cells, respectively.</p>

Monomeric and Dimeric Bromophenols from the Red Alga Ceramium Sp. with Antioxidant and Anti-Inflammatory Activities

<p>LC-MS²-based molecular networking using the Global Natural Products Social (GNPS) tool revealed a rich assortment of brominated compounds present in the antioxidant fraction of a red algal extract (<i>Ceramium</i> sp.) Further chemical investigation led to discovery of one monomeric bromophenol (lanosol isopropyl ether, <b>1</b>) and seven dimeric ones (bromourceolatols A-G, <b>2</b>-<b>8</b>), all of which are previously undescribed. Their structures were elucidated by extensive analysis of their spectroscopic data. Compounds <b>2</b>-<b>8 </b>were determined to be racemic trans-type isomers by NOESY, specific optical rotation, and ECD. Compounds <b>1</b> and <b>3</b> displayed antioxidant activity with their EC₅₀ of 44.4 and 47.0 μM, respectively, for scavenging DPPH free radicals while compounds <b>2</b> and <b>4</b> had approximate EC₅₀ values of ~ 64 μM. Furthermore, compounds <b>2</b>, <b>3</b>, and <b>7</b> exhibited relatively potent anti-inflammatory activity at 32 μM by quenching 97%, 47%, and 73% of nitric oxide induced by bacterial lipopolysaccharide in macrophage RAW264.7 cells, respectively.</p>

Tracking down the brominated single electron oxidants in recent organic red-ox transformations: photolysis and photocatalysis

A review on the wide range of organic and inorganic brominated compounds, which have been extensively used as oxidants in many organic photo-redox transformations in recent years, an area of sublime interest because of greener and milder approaches.