Additional alkaloids from Zoanthus vietnamensis with neuroprotective and anti-angiogenic effects.

A chemical investigation of the zoantharian Zoanthus vietnamensis, collected off Taiwan, yielded eleven new alkaloids, 7α-hydroxykuroshine J (1), 18ß-hydroxykuroshine J (2), 5α-hydroxyzoanthenamine (3), 5ß-hydroxyzoanthenamine (4), 14α-hydroxyzoanthenamine (5), 30-hydroxyzoanthenamine (6), 11-dehydroxy-18-epi-kuroshine A (7), 5α-hydroxykuroshine A (8), 7ß-hydroxykuroshine A (9), 11-keto-oxyzoanthamine (10), and 30-hydroxyzoanthamine (11), along with eight known compounds (12-19). The structures of these compounds were identified by detailed spectroscopic data, including HRESIMS, IR, NMR, and UV spectra. All secondary metabolites isolated from Z. vietnamensis were investigated for the anti-angiogenic effect in human endothelial progenitor cells (EPCs). Compounds 6, 7, 11, and 13 exhibited mild anti-angiogenic effect by blocking cell growth and tube formation of EPCs. The neuroprotective potential of four major compounds 12, 14, 15, and 19 against paclitaxel-induced neurotoxicity was evaluated. Pretreatment of 14 and 15 protected paclitaxel-damaged neurite outgrowth of dorsal root ganglion (DRG) neurons, without interfering the cytotoxic activity of paclitaxel on cervical cancer SiHa cells.

Zoanthamine Alkaloids from the Zoantharian Zoanthus cf. pulchellus and Their Effects in Neuroinflammation.

Two new zoanthamine alkaloids, namely 3-acetoxynorzoanthamine (1) and 3-acetoxyzoanthamine (2), have been isolated from the zoantharian Zoanthus cf. pulchellus collected off the coast of the Santa Elena Peninsula, Ecuador, together with three known derivatives: zoanthamine, norzoanthamine, and 3-hydroxynorzoanthamine. The chemical structures of 1 and 2 were determined by interpretation of their 1D and 2D NMR data and comparison with literature data. This is the first report of zoanthamine-type alkaloids from Zoanthus cf. pulchellus collected in the Tropical Eastern Pacific. The neuroinflammatory activity of all the isolated compounds was evaluated in microglia BV-2 cells and high inhibitory effects were observed in reactive oxygen species (ROS) and nitric oxide (NO) generation.

Ecdysones from Zoanthus spp. with inhibitory activity against dengue virus 2.

Bioassay-guided fractionation of an ethanolic extract of Zoanthus spp. collected in Taiwan has resulted in the isolation of one new ecdysone, zoanthone A (1), along with thirteen known compounds (2-14). The structures of these compounds were determined by spectroscopic methods, especially 2D NMR analyses. The in vitro antiviral activities of all isolated ecdysones (1-14) against dengue virus type 2 (DENV-2) were evaluated using DENV infectious system. New compound (1) exhibited potent antiviral activity (EC50=19.61 ± 2.46 µM) with a selectivity index (CC50/EC50) value of 36.7. The structure-activity relationships of isolated ecdysones against DENV-2 were concluded. Molecular docking information of 3 and NS5 polymerase was performed either.

Palytoxin-Containing Aquarium Soft Corals as an Emerging Sanitary Problem.

Palytoxin (PLTX), one the most potent marine toxins, and/or its analogs, have been identified in different marine organisms, such as Palythoa soft corals, Ostreopsis dinoflagellates, and Trichodesmium cyanobacteria. Although the main concern for human health is PLTXs entrance in the human food chain, there is growing evidence of adverse effects associated with inhalational, cutaneous, and/or ocular exposure to aquarium soft corals contaminated by PLTXs or aquaria waters. Indeed, the number of case reports describing human poisonings after handling these cnidarians is continuously increasing. In general, the signs and symptoms involve mainly the respiratory (rhinorrhea and coughing), skeletomuscular (myalgia, weakness, spasms), cardiovascular (electrocardiogram alterations), gastrointestinal (nausea), and nervous (paresthesia, ataxia, tremors) systems or apparates. The widespread phenomenon, the entity of the signs and symptoms of poisoning and the lack of control in the trade of corals as aquaria decorative elements led to consider these poisonings an emerging sanitary problem. This review summarizes literature data on human poisonings due to, or ascribed to, PLTX-containing soft corals, focusing on the different PLTX congeners identified in these organisms and their toxic potential.

Effects of macroalgae and sea urchin grazing pressure on zoantharians growth under laboratory conditions.

In the context of ocean warming, thermophilic organisms such as zoantharians are expanding and altering shallow benthic habitats. Here, a four-month laboratory experiment was performed to examine the influence of three types of macroalgae morphotypes common in the Canary Islands (turf algae, Lobophora spp., and crustose coralline algae) on the growth of two zoantharian species, Palythoa caribaeorum and Zoanthus pulchellus. Additionally, the grazing effects of echinoids Diadema africanum and Paracentrotus lividus were assessed as facilitators of substrate colonization by means of controlling macroalgae cover. Colony and algal coverages were measured at the beginning, middle and end of the experiment, and increments were calculated. Results indicated a general decrease in zoantharian colony sizes in contact with different algal types in the absence of sea urchins. However, P. caribaeorum colonies showed significant growth in the presence of D. africanum, highlighting the ecological importance of sea urchins in zoantharian population proliferation and subsequent community modification. This study represents the first investigation into zoantharian-macroalgae interactions under controlled conditions.

The flourishing and vulnerabilities of zoantharians on Southwestern Atlantic reefs.

In the Southwestern Atlantic reefs (SWA), some species of massive scleractinians and zoantharians are adapted to turbid waters, periodic desiccation, and sediment resuspension events. Moreover, phase shifts in this region have mostly been characterized by the emergence of algae and, less typically, zoantharians. However, nutrient excess and organic pollution are key drivers of the hard coral habitat degradation and may, thus, favor the emergence of novel zoantharian-dominated habitats. Many zoantharian species, particularly those from the genera Palythoa and Zoanthus, have traits that could help them thrive under conditions detrimental to reef-building corals, including rapid growth, several asexual reproduction strategies, high morphological plasticity, and generalist nutrient acquisition strategies. Thus, in a near future, stress-tolerant zoantharians may thrive in nutrient-enriched subtidal SWA locations under low heat stress, such as, upwelling. Overall, coral-zoantharian phase shifts in the SWA may decrease the species richness of reef communities, ultimately influencing ecosystem functioning and services, such as the provision of nursery habitats, fish biomass production, and coastline protection. However, zoantharians will also be threatened at intertidal zones, which are expected to experience higher heat stress, solar radiation, and sea-level rise. Although zoantharians appear to cope well with some local stressors (e.g., decreasing water quality), they are vulnerable to climate change (e.g., heatwaves), invasive species (Tubastraea spp.), microplastics, diseases, and mostly restricted to a narrow depth range (0-15 m depth) in SWA reefs. This shallow zone is particularly affected by climate change, compressing the three-dimensional habitat and limiting depth refugia in deeper SWA reefs. As mesophotic ecosystems have been hypothesized as short-term refuges to disturbances for some species, the narrow depth limit of zoantharians seems to be a potential factor that might increase their vulnerability to growing climate change pressures in SWA shallow-water reefs. Together, these could lead to both range expansions in some locations and loss of suitable reef habitats in other sites. Additional research is needed to better understand the systemic responses of these novel SWA reefs to the concert of increasing and interactive local and global stressors, and their implications for ecosystem functioning and service provisions.

Negative effects of a zoanthid competitor limit coral calcification more than ocean acidification.

Ocean acidification (OA) threatens the persistence of reef-building corals and the habitat they provide. While species-specific effects of OA on marine organisms could have cascading effects on ecological interactions like competition, few studies have identified how benthic reef competitors respond to OA. We explored how two common Caribbean competitors, branching Porites and a colonial zoanthid (Zoanthus), respond to the factorial combination of OA and competition. In the laboratory, we exposed corals, zoanthids and interacting corals and zoanthids to ambient (8.01 ± 0.03) and OA (7.68 ± 0.07) conditions for 60 days. The OA treatment had no measured effect on zoanthids or coral calcification but decreased Porites maximum PSII efficiency. Conversely, the competitive interaction significantly decreased Porites calcification but had minimal-to-no countereffects on the zoanthid. Although this interaction was not exacerbated by the 60-day OA exposure, environmental changes that enhance zoanthid performance could add to the dominance of zoanthids over corals. The lack of effects of OA on coral calcification indicates that near-term competitive interactions may have more immediate consequences for some corals than future global change scenarios. Disparate consequences of competition have implications for community structure and should be accounted for when evaluating local coral reef trajectories.

Osteoprotective effect of the marine alkaloid norzoanthamine on an osteoporosis model in ovariectomized rat.

Norzoanthamine (NZ), an alkaloid that has been isolated from the marine cnidiaria Zoanthus sp., has been shown an interesting anti-osteoporotic activity. Although its mechanism of action is not yet clear, it seems that it is different from those of currently used drugs making it particularly interesting. Previous studies have been carried out mostly in vitro. Herein, we present an in vivo study that allows to check the real potential of NZ as a protector substance by direct application into ovariectomized rat bone using a sustained delivery system. Histological and histomorphometric results in ovariectomized rats showed higher bone quality as a result of greater number of trabeculae and osteogenic activity in the group implanted with NZ, compared to controls. In contrast with the untreated controls, NZ-treated groups showed a balanced osteoblast/osteoclast number ratio, similar to that found in the normal bone. These results suggest that NZ could be useful as adjunct to other osteoporosis treatments, but probably its main therapeutic role would be as preventive therapy against bone deterioration.

Reef fish assemblages associated to new mat-forming zoantharian communities in the Canary Islands.

Proliferations of zoantharians along tropical and subtropical regions are increasingly common and usually associated with anthropogenic impacts and ecosystem degradation. In the Canary Islands, we studied how the dominance in the substrate of Palythoa caribaeorum and Zoanthus pulchellus affected fish communities. For that purpose, we recorded the composition and biodiversity of fish assemblages associated to both zoantharian and macroalgae dominated habitats. In general terms, we found significant reductions of total fish abundance and richness at P. caribaeorum dominated habitats compared with macroalgae stands. However, in terms of trophic structure, there were significant changes within both zoantharian habitats depending on their coverages of the substrate. Herbivores and small invertebrate feeders, which are more adapted to forage in the macroalgae canopy, were less abundant in zoantharian habitats. This study demonstrates that the increasing dominance of zoantharians throughout the archipelago restructure the ecosystems and impact the native fish communities, that may offer a positive feedback for invasive tropical species to thrive.

Zoantharian Endosymbiont Community Dynamics During a Stress Event.

Coral reefs are complex ecosystems composed of many interacting species. One ecologically important group consists of zoantharians, which are closely related to reef-building corals. Like corals, zoantharians form mutualistic symbioses with dinoflagellate micro-algae (family Symbiodiniaceae), but their associations remain underexplored. To examine the degree to which zoantharians exhibit altered symbiont dynamics under changing environmental conditions, we reciprocally transplanted colonies of Zoanthus sansibaricus between intertidal (2 m) and subtidal (26 m) depths within a reef in Okinawa, Japan. At this location, Z. sansibaricus can associate with three Symbiodiniaceae species from two genera distributed along a light and depth gradient. We developed species-specific molecular assays and sampled colonies pre- and post-transplantation to analyze symbiont community diversity. Despite large environmental differences across depths, we detected few symbiont compositional changes resulting from transplantation stress. Colonies sourced from the intertidal zone associated with mixtures of a "shallow" Symbiodinium sp. and a "shallow" Cladocopium sp. independent of whether they were transplanted to shallow or deep waters. Colonies sourced from the subtidal zone were dominated by a "deep" Cladocopium sp. regardless of transplant depth. Subtidal colonies brought to shallow depths did not transition to the presumably high-light adapted shallow symbionts present in the new environment, but rather bleached and died. These patterns mirror observations of highly stable coral-algal associations subjected to depth transplantation. Our results indicate that Zoanthus-Symbiodiniaceae symbioses remain stable despite stress, suggesting these important reef community members have relatively low capacity to shuffle to more stress-tolerant micro-algae in response to ongoing climate change.

[The feeding of Zoanthus sp. on two microalgae species.] / 花群珊瑚对两种微藻的摄食.

In this study, we investigated whether Zoanthus sp. feed on two common microalgae, Platymonas subcordiformis and Isochrysis galbana, using the methods of carbon clearance rate, DNA marker, and histological analyses. The results showed that carbon clearance rate of I. galbana by Zoanthus sp. was significantly higher than that of P. subcordiformis, which were 0.44 and 0.11 pg·mL-1·polyp-1·h-1, respectively. 162 bp of 18S rRNA gene from P. subcordiformis and 442 bp of enoyl-ACP reductase gene from I. galbana were used as molecular nutrition markers, both of them were successfully amplified from the Zoanthus sp. fed by both algae species. Results of the histological analyses demonstrated that pholyp from feeding group showed a widen mesentery. Lots of food vacuoles presented in tissues of mesentery and gastrodermis. Undigested cell body of P. subcordiformis and I. galbana could also be found in some food vacuoles around siphonoglyphe as well as the gastrodermis in body wall. Therefore, results from carbon clearance rate, histological and DNA marker results all indicated that Zoanthus sp. could feed on P. subcordiformis and I. galbana.

A new species of Achelia (Pycnogonida: Ammotheidae) and first records of intertidal sea spiders found on Zoanthus (Cnidaria: Zoantharia) from Karachi, Pakistan.

Ten intertidal sea spider (Pycnogonida) species from five families - Pycnogonidae (1 species), Ammotheidae (3 species), Callipallenidae (3 species), Phoxichilidiidae (2 species) and Endeidae (1 species) - are reported in the present study. Out of these ten species, four are first records from Pakistan, including a new species, Achelia karachiensis sp. nov. Intertidal zoanthid colonies have been found to provide shelter and food to a large and diverse Pycnogonid population at Sandspit and the Buleji, Karachi coast. This study highlights the significance of the intertidal fauna of pycnogonids of these areas and contributes to our understanding of the species diversity from the Karachi coast.

Trophic and stoichiometric consequences of nutrification for the intertidal tropical zoanthid Zoanthus sociatus.

Zoanthids are conspicuous and abundant members of intertidal environments, where they are exposed to large environmental fluctuations and subject to increasing loads of anthropogenic nutrients. Here we assess the trophic ecology and stoichiometric consequences of nutrient loading for symbiotic zoanthids inhabiting different intertidal habitats. More specifically, we analysed the stable isotope signature (δ13C and δ15N), elemental composition (C, N and P) and stoichiometry (C:N, C:P, N:P) of Zoanthus sociatus differently exposed to nutrification. Results suggest that autotrophy is the main feeding mode of zoanthids and that the effect water nutrient content differently affects the elemental phenotype of zoanthids depending on tidal habitat. Additionally, habitat effects on Z. sociatus P-related stoichiometric traits highlight functional differences likely associated with variation in Symbiodinium density. These findings provide an innovative approach to assess how cnidarian-dinoflagellate symbioses response to ecosystem changes in environmentally dynamic reef flats, particularly nutrient loading.

Microcystin-LR Detected in a Low Molecular Weight Fraction from a Crude Extract of Zoanthus sociatus.

Cnidarian constitutes a great source of bioactive compounds. However, research involving peptides from organisms belonging to the order Zoanthidea has received very little attention, contrasting to the numerous studies of the order Actiniaria, from which hundreds of toxic peptides and proteins have been reported. In this work, we performed a mass spectrometry analysis of a low molecular weight (LMW) fraction previously reported as lethal to mice. The low molecular weight (LMW) fraction was obtained by gel filtration of a Zoanthus sociatus (order Zoanthidea) crude extract with a Sephadex G-50, and then analyzed by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF) mass spectrometry (MS) in positive ion reflector mode from m/z 700 to m/z 4000. Afterwards, some of the most intense and representative MS ions were fragmented by MS/MS with no significant results obtained by Protein Pilot protein identification software and the Mascot algorithm search. However, microcystin masses were detected by mass-matching against libraries of non-ribosomal peptide database (NORINE). Subsequent reversed-phase C18 HPLC (in isocratic elution mode) and mass spectrometry analyses corroborated the presence of the cyanotoxin Microcystin-LR (MC-LR). To the best of our knowledge, this finding constitutes the first report of MC-LR in Z. sociatus, and one of the few evidences of such cyanotoxin in cnidarians.

Phylogeny of Symbiodinium populations in zoantharians of the northern Persian Gulf.

Zoantharians of the Persian Gulf (PG) experience periods of anomalous high temperature, irradiance and desiccation. Their survival largely relies on the symbiotic relationship with single celled dinoflagellates of the genus Symbiodinium. However, the phylogeny of symbionts of zoantharians has not been investigated in the region. In this study, the second internal transcribed spacer region of ribosomal DNA (ITS2) was used to recognize in hospite populations of Symbiodinium in Palythoa aff. mutuki, Palythoa tuberculosa and Zoanthus sansibaricus colonies from Hengam, Kish, Larak, and Qeshm Islands, in the PG. The results showed subclade D1-4 and a variant of A1, were the most prevalent subclades of Symbiodinium. Predominance of stress tolerant subclade D1-4 and putatively radiation tolerant variant of A1 of Symbiodinium in zoantharian species might suggest an adaptation strategy to the extreme physical environment of the PG.